X Chemistry Guess Paper 2027

Are you searching for the X Chemistry Guess Paper 2027 based on the latest board paper pattern? Here you’ll find 100% important questions, MCQs, short and long questions, and chapter-wise important concepts that are most expected in the 2026 board exams.

Welcome to the X Chemistry Guess Paper 2026 prepared by Inam Jazbi, your trusted source for quality educational content and exam preparation. This post includes chapter-wise important MCQs, short questions, and long questions carefully selected from past board papers, new syllabus, and model tests to help you score top marks in your upcoming exams.

Whether you’re following the new textbook or revising for your final term, this Chemistry Class 10 Guess Paper 2027 by Inam Jazbi highlights the most expected questions, repeated concepts, and key topics every student must prepare.

💡 What’s Inside:
✅ 100% important MCQs, short & long questions
✅ Based on new paper pattern 2027
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✅ Ideal for board exam preparation
✅ Based on New Syllabus & Board Paper Scheme 2026
✅ Includes Most Repeated MCQs & Short Questions
✅ Prepared by Experienced Teacher
✅ Perfect for Final Term & Board Exams

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X Chemistry MCQs for Board Paper 2027

Short Answer Questions

✏️ X-CHEMISTRY Guess Paper 2027 with solution
Dr Inam Ul Haq Jazbi ✏️

Total Marks: 60

Time: 3 Hours

General Instructions

Section – A: contains 12 MCQs and all of them are to be answered.

Section – B: consists of 12 short-answer questions of which 8 are to be answered (24 marks).

Section – C: consists of 6 long-answer questions of which 4 are to be answered (24 marks).

Short Answer Questions

✏️ Section-B (Short-Answer Questions) 8 Questions 3 marks each (24) ✏️

1️⃣ Define any three of the following:

Equilibrium constant ⚖️, reaction quotient 📊, extent of a reaction ➡️, pH 🌡️, Indicator 🧪, Neutralization ⚡, Titration ⚗️, alicyclic compounds 🔄, aromatic compounds 🌸, catenation 🔗, aldoses 🍬, ketoses 🍭, saccharides 🍯, functional group 🧬, Peptide linkage 🔬, Saponification 🧼, lipids 🧴, enzymes ⚙️, isomerism 🔀, Bloor’s reagent 🧪, fatty acid 🥓, ozone hole 🌍, organic chemistry 📚, Biochemistry 🧫, Environmental chemistry 🌿, Analytical Chemistry 📊, Qualitative Analysis 🔎, Quantitative Analysis 📈, accuracy ✅, precision 🎯, titrant ⚗️, analyte 🧪, Indicator 🧭, parameter 📐, homologous series 🔗, alkyl radicals ⚡, glycosidic linkage 🍬, nucleotide 🧬, Potentiometry ⚡, stationary phase 🛑, mobile phase 🚀, retention time ⏱️, active mass ⚖️, dynamic equilibrium 🔄, chromatography 🧪.

2️⃣ Write down three differences between any one of the following:

(i) Troposphere 🌍 and Stratosphere ☁️
(ii) Reversible 🔄 and irreversible reactions ❌
(iii) Saturated 🟢 and unsaturated hydrocarbons 🟠
(iv) Dextrorotary ➡️ and Levorotatory Sugars ⬅️
(v) Quantitative 📈 and qualitative analysis 🔎
(vi) Titrimetric ⚗️ and gravimetric analysis ⚖️
(vii) Classical 📚 and Instrumental Methods 🎛️
(viii) Fat-soluble 🧴 and water-soluble vitamins 💧
(ix) DNA 🧬 and RNA 🧬
(x) Fat 🥓 and oil 🛢️
(xi) Aldoses 🍬 and ketoses 🍭
(xii) Forward ➡️ and reverse reactions ⬅️

3️⃣ Chemical Equilibrium

🧪 Define chemical equilibrium state with its any three macroscopic properties. Why chemical equilibrium is dynamic? Explain it with one example.

OR

What is equilibrium constant? Write down any three characteristics of equilibrium constant. Why equilibrium constant may or may not have unit? Justify with example.

4️⃣ Equilibrium Constant Expressions (Kc)

Write down Equilibrium Constant Expression (Kc) and unit of Kc for any 3 of the following balanced reversible reactions:

(i) N₂(g) + 2O₂(g) ⇌ 2NO₂(g) ⚗️
(ii) H₂(g) + I₂(g) ⇌ 2HI(g) 🧪
(iii) CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(g) 💧
(iv) 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) 🔥
(v) N₂(g) + 3H₂(g) ⇌ 2NH₃(g) 🌿
(vi) CO(g) + 3H₂(g) ⇌ CH₄(g) + H₂O(g) ⚡

5️⃣

(a) What are conjugate acids and conjugate bases of each of the following?
HS⁻, H₃O⁺, H₂PO₄⁻, HSO₄⁻, HF, CH₃COOH, [Al(H₂O)₆]³⁺, OH⁻, HCO₃, HPO₄²⁻, CH₃NH₂, CO₃²⁻

(b) Which of the following behave both as Bronsted acids and Bronsted bases?
H₂O, HCO₃⁻, H₂SO₄, H₃PO₄, HS⁻

OR

What are conjugate acid-base pairs? Also define conjugate acid and conjugate base.
Identify acid, base, conjugate acid and conjugate base in the following reactions:
➡️ CH₃COOH + H₂O ⇌ H₃O⁺ + CHCOO₃⁻
➡️ NH₃ + HCl ⇌ NH₄⁺ + Cl⁻
➡️ H₂O + NH₃ ⇌ NH₄⁺ + OH⁻

6️⃣

State vital force theory and how was this theory discarded by Wohler?

OR

Write the names and structural formulae of six carbons alkanes, alkenes, alkyne, cycloalkane and aromatic hydrocarbons.

OR

Draw the structures of following compounds:
(i) 2,3-dimethylpentane
(ii) 3-ethyl-1-hexene
(iii) 2-butyne
(iv) 2,4-hexadiene
(v) 3-methyl-1,4-hexadiyne
(vi) 2-hepten-5-yne
(vii) 2-pentyne
(viii) neopentane
(ix) iso-propyl alcohol
(x) Phenol or toluene
(xi) iso-butane
(xii) Cyclohexane

7️⃣

Define structural formula. Write down the molecular, structural and condensed formulae of the following compounds:
Ethane, Ethene and Ethyne, ethyl alcohol, acetic acid, acetone, n-butane, isobutane, methyl acetate, dimethyl amine

OR

Define functional group. Identify the functional groups in the following compounds:
(a) CH₃CHO (Aldehydic group)
(b) CH₃CH₂CH₂OH (primary alcoholic group)
(c) CH₃COCH₃ (ketonic carbonyl group)
(d) C₃H₇COOH (carboxylic group)
(e) CH₂=CHCH₃ (double bond)
(f) CH₃OCH₃
(g) CH₃CH₂COOCH₃

8️⃣

Define salt and its three types with two examples each. Give three uses of salts. Also write any three methods of preparation of salts with equation. Write down any one use of the following salts:
Copper sulphate, Calcium sulphate dehydrated, iron sulphate hepta hydrated, sodium hydrogen carbonate, barium sulphate, potassium permangate.

OR

What are enzymes? Write one use of enzymes yeast, cellulase, lipase, lactase and amylase.

OR

What is homologous series? Name the any two common homologous series with examples. Write down the general characteristics of homologous series. Write the possible isomers of Pentane with their common name and IUPAC name.

OR

What is alkyl radicals? Give its type formula and general formula. Explain with structure different radicals of butane. What is the difference of alkyl radicals obtained from propane?

9️⃣

Elaborate ionization equation of water. Explain in detail that how water ionization is related with pH of solution? Also define pH, pOH and neutralization. Prove pH + pOH = 14.

OR

Define buffers. What is the composition of buffers? How are they prepared? Discuss its importance in our daily life.

🔟

Write any three significant uses of Carbohydrates and lipids.

OR

What are amino acids and peptide bond? How peptide bond is formed? Also explain dipeptides & tripeptides.

OR

Write down three characteristics of organic compounds.

OR

Write down three uses of organic compounds.

1️⃣1️⃣

Give reason:
(i) Why Silicon compounds are lesser than that of Carbon compounds?
(ii) Why pure water is considered as weak electrolyte?
(iii) Justify the petroleum is ‘black gold’.
(iv) Alkanes are said to be saturated hydrocarbons.
(v) Justify that water soluble vitamins are not injurious to health.
(vi) Justify that greenhouse effect leads to global warming.
(vii) Justify that “water is solvent”.
(viii) How is vegetable oil converted into saturated fat (ghee)?
(ix) Why chemical equilibrium is considered dynamic not static?
(x) Why the temperature on top of a mountain is colder than at sea level?
(xi) Why organic compounds have great diversity in magnitude.
(xii) Why IR spectroscopy is more advantageous than UV-vis spectroscopy? explain.

1️⃣2️⃣

Complete the following neutralization reactions between acids and bases:
(i) Ca(OH)₂ + H₂SO₄ → __________ + __________.
(ii) NaOH + H₂SO₄ → __________ + __________.
(iii) NaOH + H₃PO₄ → __________ + __________.

OR

Define vitamin and complete the following chart:

Vitamin Name	Sources	Deficiency Disease
Vitamin A	__________	__________
Vitamin D	__________	__________
Vitamin E	__________	__________
Vitamin K	__________	__________
Vitamin C	__________	__________

1️⃣3️⃣

What are Oligosaccharides, Disaccharides and polysaccharides. Give their examples and sources.

OR

What are the carbohydrates? Explain sources and types of carbohydrates.

1️⃣4️⃣

What are amino acids and give their general structure? How many Essential and Non-essential Amino Acids are there? Write down the range of Number of Amino Acids and molecular weights of Proteins.

OR

What are fatty acids? Give their examples and chemical nature.

1️⃣5️⃣

Briefly describe any three beneficial impacts of pharmaceutical industry on human society.

OR

Give general formula for Alkanes, Alkenes and Alkynes. Identify Alkanes, alkenes, alkynes, cycloalkanes and aromatics in each of the following:
C₆H₆, C₂H₄, C₃H₄, C₃H₈, C₆H₁₂, C₅H₈, C₄H₆, C₆H₅OH

1️⃣6️⃣

Write down causes of following diseases:
(i) Diarrheal Diseases
(ii) Dysentery
(iii) Cholera
(iv) Crytosporidium
(v) Fluorosis
(vi) Hepatitis
(vii) Hookworm
(viii) Typhoid

OR

Define atmosphere. Discuss its composition. Write down the names of different atmospheric layers with their altitude and temperatures.

1️⃣7️⃣

What is the cause of acid rain? Explain. Write down the effects of acid rain and global warming.

OR

Give difference between primary and secondary air pollutants. Identify as primary or secondary air pollutant: SO₂, CH₄, HNO₃, NH₃, H₂SO₄ and O₃

1️⃣8️⃣

Describe the composition of water. Write degree of Hardness of water on the basis of Dissolved Ca Ions (mg/L).

1️⃣9️⃣

List down the applications of conductometry.

OR

Define qualitative analysis. What are organic and inorganic qualitative analyses. Give their examples.

2️⃣0️⃣

What is error? Write down causes of errors with their %. Write down brief note systematic and random errors with two examples each.

OR

Define quantitative analysis. What are the physical and chemical methods of quantitative analysis?

OR

What is vitamin D? Give its sources and importance.

Short Answer Questions

✏️ Section-C (Long-Answer Questions) 4 Questions 6 marks each (24) ✏️

2️⃣1️⃣

State law of mass action and define Kc. Derive an expression for equilibrium constant for a general reaction.
Predict, which system at equilibrium, will contain maximum amount of reactant or maximum amount of product:

(i) 2CO₂ ⇌ 2CO + O₂ Kc = 3.1 ×10⁻¹⁸ mol.dm⁻³
(ii) 2O₃ ⇌ 3O₂ Kc = 5.9 ×10⁵⁵ mol.dm⁻³

2️⃣2️⃣

State and explain Bronsted-Lowry acid-base theory or Lewis concept of acids and bases with examples?
Explain with an example that water is a Bronsted-Lowry acid as well as Bronsted-Lowry base.
Give limitations of Bronsted-Lowry theory.

OR

State three different theories about concepts of acids and bases with one example and also indicate one limitation of each concept.
Which of the following is/are Arrhenius acids and bases?
(a) Ca(OH)₂
(b) HNO₃
(c) NaOH
(d) H₂SO₄
(e) KOH

2️⃣3️⃣

Define functional group. Write different functional groups which contain carbon, hydrogen and oxygen.

OR

Define nomenclature and describe IUPAC nomenclature rules for alkynes and alkanes. Write down IUPAC names of following:

2️⃣4️⃣

What are the main sources of organic compounds? Mention with special reference of coal, petroleum and natural gas.

OR

What do you mean by diversity and magnitude of organic compounds? Give at least 5 reasons.

OR

Give classification of organic compounds and the important characteristic of organic compounds.

2️⃣5️⃣

What are Lipids? Write down the sources and uses of lipids. Write five differences between Fats and Oils.

OR

What are proteins and peptide bond? How peptide bond is formed in dipeptides and tripeptides? Write down the range of Number of Amino Acids & molecular weights of Proteins. Give importance & sources of proteins.

2️⃣6️⃣

Describe in detail nucleic acids, RNA and DNA. Give five points to differentiate between DNA and RNA. Write down importance of deoxyribonucleic acid (DNA).

OR

What are vitamins. Differentiate its two types with their sources. Name the diseases caused by the deficiency of both types of vitamins.

2️⃣7️⃣

What is saponification? Describe the raw materials used in the preparation of soap. Describe process of Saponification with the help of flow sheet diagram.

OR

Define Atmosphere. Enlist the layers of atmosphere. Differentiate between troposphere and stratosphere?

2️⃣8️⃣

Justify that electrochemical methods depend upon electrochemical cells.

OR

What is Titrimetric Analysis? Describe how it is performed with diagram.

2️⃣9️⃣

Explain the process of preparation sugar from sugar cane.

3️⃣0️⃣

What is Ozone? How does Ozone depletion occur by Chlorofluorocarbons (CFCs) also mention some adverse impact of it?

OR

Describe global warming. Justify that greenhouse effect leads to global warming.

3️⃣1️⃣

Describe Gas Chromatography with diagram also write two uses of gas chromatography.

OR

Describe HPLC in details.

OR

What is spectroscopy? How is it used in the chemical analysis of a substance? Also discuss its types.

3️⃣2️⃣

Differentiate between Soft Water and Hard Water and describe different methods of removing temporary and permanent hardness. Write down 5 disadvantages of hard water.

3️⃣3️⃣

Definition Water Pollution. Write down its Causes and Effects on Life.

OR

Define pollutant. Enlist the names of seven types of pollutants. What are primary and secondary air pollutants? Give the sources, environmental and health risks of the following:
COₓ, SOₓ, NOₓ, lead, ozone

✏️ Numericals ✏️

1️⃣

Equilibrium occurs when nitrogen monoxide gas reacts with oxygen gas to form nitrogen dioxide gas:
2NO₍g₎ + O₂₍g₎ ⇌ 2NO₂₍g₎

At equilibrium at 230°C, the concentrations are measured to be:
[NO] = 0.0542 mol dm⁻³, [O₂] = 0.127 mol dm⁻³ and [NO₂] = 15.5 mol dm⁻³

Calculate the equilibrium constant at this temperature. (Book problem 1; page 8)
Answer: 6.44 × 10⁵ mol⁻¹ dm³

2️⃣

A reaction takes place between iron and chloride ion as:
Fe³⁺ + 4Cl⁻ ⇌ FeCl₄⁻

At equilibrium the concentrations are measured to be:
Fe³⁺ = 0.2 mol dm⁻³, Cl⁻ = 0.28 mol dm⁻³ and FeCl₄⁻ = 0.95 × 10⁻⁴ mol dm⁻³

Calculate equilibrium constant Kc for given reaction. (Book problem 1; page 9)
Answer: 7.2 × 10⁻² mol⁻⁴ dm¹²

3️⃣

For the reaction: H₂(g) + I₂(g) ⇌ 2HI(g) (Kc = 57.0); the concentrations of H₂(g), I₂(g) and HI(g) at time t are:
[H₂]ₜ = 0.10 mol dm⁻³, [I₂]ₜ = 0.20 mol dm⁻³, [HI]ₜ = 0.40 mol dm⁻³

Predict in which direction reaction will move to achieve equilibrium.
Answer: Qc (8.0) < Kc (57.0), forward direction

4️⃣

When hydrogen reacts with iodine at 25°C to form hydrogen iodide by a reversible reaction as follows:
H₂₍g₎ + I₂₍g₎ ⇌ 2HI₍g₎

The equilibrium concentrations are:
[H₂] = 0.05 mol dm⁻³; [I₂] = 0.06 mol dm⁻³; [HI] = 0.49 mol dm⁻³

Calculate the equilibrium constant for this reaction. (Book problem 1; page 9)
Answer: Kc = 80

5️⃣

For the formation of ammonia by Haber’s process, hydrogen and nitrogen react reversibly at 500°C as follows:
N₂₍g₎ + 3H₂₍g₎ ⇌ 2NH₃₍g₎ , Kc = 3.0 × 10⁻⁹

The equilibrium concentrations of these gases are: nitrogen 0.602 mol dm⁻³; hydrogen 0.420 mol dm⁻³ and ammonia 0.113 mol dm⁻³.
What is value of Kc?
Answer: 0.286 mol⁻² dm⁶

6️⃣

Nitrogen oxides are air pollutants produced by the reaction of nitrogen and oxygen at high temperature. At 2000°C, the value of the equilibrium constant for the given reaction is 4.1 × 10⁻⁴:
N₂(g) + O₂(g) ⇌ 2NO(g)

Find the concentration of NO in an equilibrium mixture at 1 atmosphere at 2000°C. In air, [N₂] = 0.036 mol/L and [O₂] = 0.0089 mol/L. (Book problem 3; page 10)
Answer: 3.6 × 10⁻⁴ mol/L

7️⃣

Find pH, pOH, [OH⁻] and [H⁺] of 2.46 × 10⁻⁹ M KOH solution.
Answer: [OH⁻] = 2.46 × 10⁻⁹ M, [H⁺] = 4.07 × 10⁻⁶ M, pH = 5.39, pOH = 8.61

8️⃣

A solution of HCl has pH of 2.3. Calculate its pOH and [H⁺]? (Book)
Answer: pOH = 11.7, [H⁺] = 5.01 × 10⁻³

9️⃣

Find the pH of 0.01 M sulphuric acid.
Answer: pH = 1.7

🔟

A solution of H₂SO₄ has pH of 1.05, calculate its pOH and [H⁺].
Answer: [H⁺] = 0.089 M, pOH = 12.95

1️⃣1️⃣

Calculate pH, pOH, [OH⁻], and [H⁺] of 1 × 10⁻⁸ M NaOH.
Answer: pH ≈ 6.98, pOH ≈ 7.02, [OH⁻] ≈ 1.0 × 10⁻⁸ M, [H⁺] ≈ 1.05 × 10⁻⁷ M

Short Answer Questions

✏️ X-CHEMISTRY Interactive MCQs (Click MCQ to reveal answer and reason
Dr Inam Ul Haq Jazbi ✏️

1. For the reaction, 2A(g) + B(g) ⇌ 3C(g) the expression for the equilibrium constant is:

(a) [2A][B]/[3C]

(b) [A]²[B]/[C]³

(d) [C]³/[A]²[B]

Correct: (d). Reason → Equilibrium constant is products over reactants with powers equal to coefficients.

2. Equilibrium constant value K_c is equal to;

(a) Qc/Kr

(b) Kr/Kf

(d) Kf/Kr

Correct: (d). Reason → K_c is the ratio of forward (Kf) to reverse (Kr) rate constants.

3. NH₃ can be a base according to:

(a) Arrhenius theory

(b) Bronsted-Lowry theory

(d) Both b and c

Correct: (d). Reason → NH₃ accepts a proton (Bronsted-Lowry) and donates an electron pair (Lewis).

4. Which of the following is a Lewis base?

(a) HNO₃

(b) AlCl₃

(d) CN⁻

Correct: (d). Reason → CN⁻ has a lone pair of electrons to donate, making it a Lewis base.

5. The general formula of alkynes is:

(a) C_nH_2n

(b) C_nH_2n+1

(d) C_nH_2n+2

Correct: (c). Reason → Alkynes have a triple bond, reducing hydrogen count to C_nH_2n–2.

6. Which of the following is an alcohol?

(a) CH₃CHO

(b) CH₃CH₂OCH₃

(d) HCOOH

Correct: (c). Reason → Alcohols contain the –OH group attached to carbon; CH₃CH₂OH is ethanol.

7. Which one of the following is polysaccharide?

(a) Fructose

(b) Maltose

(d) None

Correct: (c). Reason → Starch is a polysaccharide made of glucose units; fructose and maltose are simple sugars.

8. Cellulose content in Cotton is:

(a) 70%

(b) 95%

(d) 90%

Correct: (b). Reason → Cotton is almost pure cellulose, about 95% content.

9. Ozone layer is part of:

(a) Stratosphere

(b) Mesosphere

(d) Troposphere

Correct: (a). Reason → The ozone layer lies in the stratosphere, protecting Earth from UV radiation.

10. It is used to assess concentration or amount of given atomic, molecular or ionic chemical.

(a) Chromatography

(b) Spectroscopy

(d) Potentiometry

Correct: (b). Reason → Spectroscopy measures concentration by analyzing absorption/emission of radiation.

11. Surfactants reduce the......... of water.

(a) Surface tension

(b) Viscosity

(d) Melting point

Correct: (a). Reason → Surfactants lower surface tension by disrupting hydrogen bonding at the surface.

12. The centrifuge machine is used for separation of:

(a) Crystal

(b) pH

(d) Juice

Correct: (a). Reason → Centrifugation separates Crystal

13. Insulin which enables our body to use glucose obtained from food or glycogen is basically:

(a) an enzyme

(b) a hormone

(d) a mineral

Correct: (b). Reason → Insulin is a peptide hormone secreted by the pancreas to regulate blood glucose.

14. Vital force theory was introduced by:

(a) Robert Boyle

(b) J. J. Berzelius

(d) Wohler

Correct: (b). Reason → J. J. Berzelius proposed vital force theory, later disproved by Wohler’s urea synthesis.

15. Lactose enzymes are used:

(a) in production of bread

(b) to make ice cream sweeter

(d) to maintain colour

Correct: (b). Reason → Lactase breaks down lactose into sweeter sugars (glucose + galactose), used in ice cream.

16. The unit of K_c for reaction; N₂(g) + O₂(g) ⇌ 2NO(g)

(a) mol dm⁻³

(b) mol⁻² dm⁶

(d) no unit

Correct: (d). Reason → For this reaction, the number of moles of products equals reactants, so K_c is dimensionless (no unit).

17. The system is stable in equilibrium when:

(a) Q_c = K_c

(b) Q_c > K_c

(d) None of these

Correct: (a). Reason → At equilibrium, the reaction quotient Q_c equals the equilibrium constant K_c.

18. The value of K_c increases when:

(a) [Reactant] = [Product]

(b) [Product] is more

(d) [Product] is less

Correct: (b). Reason → K_c = [Products]/[Reactants]; higher product concentration increases K_c.

19. Corrosive effect on skin is caused by:

(a) Acid

(b) Base

(d) Both a and b

Correct: (d). Reason → Both strong acids and strong bases are corrosive and damage skin tissue.

20. Preservatives are used to preserve:

(a) Acid

(b) Base

(d) Water

Correct: (c). Reason → Preservatives prevent spoilage of food by inhibiting microbial growth.

21. Rickets is caused by the deficiency of:

(a) Vitamin A

(b) Vitamin B

(d) Vitamin D

Correct: (d). Reason → Rickets is a bone‑softening disease caused by Vitamin D deficiency.

22. For a reversible reaction, if the concentration of both reactants are DOUBLED, then equilibrium constant is:

(a) Also doubled

(b) Halved

(d) Not changed

Correct: (d). Reason → K_c depends only on temperature, not on initial concentrations.

23. Nitrogen and hydrogen were reacted together to make ammonia:
N₂ + 3H₂ ⇌ 2NH₃ ; K_c = 2.86 mol⁻² dm⁶
What will be present in the equilibrium mixture?

(a) NH₃ only

(b) N₂, H₂ and NH₃

(d) H₂ only

Correct: (b). Reason → At equilibrium, both reactants and product coexist in the mixture.

24. The error caused by improper functioning of instrument is:

(a) Determinant Error

(b) Indeterminant Error

(d) Both a & c

Correct: (d). Reason → Systematic errors also called Determinant Error arise from faulty instruments or consistent bias in measurement.

25. Which one of the following gives orange‑red flame in flame test?

(a) LiCl

(b) NaCl

(d) CaCl₂

Correct: (d). Reason → Calcium salts impart an orange‑red flame color in flame tests.

26. The % of equipment failure in creating errors and deviations is:

(a) 13

(b) 16

(d) none of them

Correct: (a). Reason → Equipment failure contributes about 13% to errors and deviations.

27. The wavelength range of ultraviolet and visible spectroscopy is:

(a) 192 to 900 nm

(b) 152 to 800 nm

(d) None of them

Correct: (a). Reason → UV‑Vis spectroscopy typically covers ~190–900 nm range.

28. The number of hydrogen bonds formed by one water molecule is/are:

(a) Two

(b) Three

(d) One

Correct: (c). Reason → Each H₂O molecule can form up to 4 hydrogen bonds (2 as donor, 2 as acceptor).

29. In hard water, the amount of dissolved Ca ions in mg/L is:

(a) 0 to 16.1

(b) 16.1 to 60

(d) 121 to 180

Correct: (d). Reason → Hard water is classified when Ca²⁺ concentration is 121–180 mg/L.

30. For which system does the equilibrium constant, K_c has units of concentration?

(a) CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(g)

(b) N₂(g) + O₂(g) ⇌ 2NO(g)

(d) N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

Correct: (d). Reason → Δn = (2 – 4) = –2, so K_c has units of concentration (mol⁻² dm⁶).

31. The functional groups –CHO and –COOH are used respectively for:

(a) Aldehydes and Ester

(b) Aldehydes and Carboxylic acids

(d) Ketones and Carboxylic acids

Correct: (b). Reason → –CHO denotes aldehydes, –COOH denotes carboxylic acids.

32. Which of the following is NOT an Arrhenius acid?

(a) HCl

(b) CO₂

(d) H₂SO₄

Correct: (b). Reason → CO₂ is not an Arrhenius acid; it does not directly release H⁺ ions in water.

Short Answer Questions

✏️ Smart Answers of Section-B (Short-Answer Questions) ✏️

1️⃣ Define any three of the following:

Equilibrium constant, reaction quotient, extent of a reaction, pH, Indicator, Neutralization, Titration, alicyclic compounds, aromatic compounds, catenation, aldoses, ketoses, saccharides, functional group, Peptide linkage, Saponification, lipids, enzymes, isomerism, Bloor’s reagent, fatty acid, ozone hole, organic chemistry, Biochemistry, Environmental chemistry, Analytical Chemistry, Qualitative Analysis, Quantitative Analysis, accuracy, precision, titrant, analyte, Indicator, parameter, homologous series, alkyl radicals, glycosidic linkage, nucleotide, Potentiometry, stationary phase, mobile phase, retention time, active mass, dynamic equilibrium, chromatography.

Answer

🔬 Chemical Equilibrium Terms

⚖️ Active Mass
It is the molar concentration (mol dm⁻³) of a substance taking part in a reaction, represented by [ ].

📊 Equilibrium Constant (Kc)
The equilibrium constant (Kc) of a reversible reaction is the ratio of the product of equilibrium molar concentrations (active masses) of products to that of reactants, each raised to the power of their respective stoichiometric coefficients in the balanced chemical equation, at a constant temperature.
Kc = Kᵳ/Kᵣ = [P]/[R] = [C]ᶜ [D]ᵈ/[A]ᵃ [B]ᵇ

🔁 Dynamic Equilibrium
Dynamic equilibrium is the condition where forward and reverse processes occur continuously at the same rate, so no overall change is observed in the system keeping the system stable.

🧪 Reaction Quotient (Qc)
The reaction quotient (Qc) is the ratio of the concentrations of products to reactants at any point (not necessarily at equilibrium) during a reaction, each raised to the power of their coefficients. It is the same expression as Kc but calculated using initial (non-equilibrium) concentrations.
Qc = [Pᵢ]/[Rᵢ] = [Cᵢ]ᶜ [Dᵢ]ᵈ/[Aᵢ]ᵃ [Bᵢ]ᵇ

📈 Extent of Reaction
It is the measure of how far reactants are converted into products.

🧪 Acids, Bases & Titration

pH 🧫
pH is a measure of acidity or basicity defined as the negative logarithm of the molar hydrogen ions concentration of a solution ranging from 0 to 14. pH = –log[H⁺].

🎨 Indicator
It is a weak organic acid or base that changes colour over a specific pH range to show end-point during titrations.

💧 Neutralization
It is the reaction between an Arrhenius acid and an Arrhenius base to form salt and water.

🧪📐 Titration
It is a method to determine the concentration of an unknown solution (analyte) using a solution of known concentration (titrant).

💉 Titrant
It is the solution of known concentration added during titration.

🧬 Analyte
It is the substance whose concentration is being determined.

🌱 Organic Chemistry Basics

Organic Chemistry 🧪
It is the study of carbon-containing compounds mainly hydrocarbons and their derivatives and their reactions.

Catenation 🔗
It is the ability of carbon to form chains by bonding with itself. It is the self-linking property of carbon.

Functional Group 🧩
It is an atom or group of atoms or multiple bonds that gives characteristic properties to an organic compound. e.g. –OH group is the functional group of alcohol family (R–OH).

Isomerism 🔄
Isomerism is the existence of two or more compounds with same molecular formula but different structures and properties. (This is mainly because of different structural or spatial arrangements.)

Homologous Series 🧬
A family of organic compounds with similar properties and a common functional group, differing by –CH₂.

Alkyl Radical 🌿
A hydrocarbon group formed by removal of one hydrogen atom from an alkane (e.g., –CH₃).

Acyclic (Aliphatic) Compounds 🔓
Open-chain (aliphatic) compounds consist of carbon atoms arranged in open, continuous straight or branched chains (rather than closed cyclic structures), with the terminal (end) carbon atoms not connected to each other. Open-chain compounds are also known as aliphatic compounds. Examples: n-pentane, isopentane, propane, butane.

Alicyclic Compounds 🔵
These are the cyclic or Carbocyclic compounds without benzene rings. Cyclopropane (C₃H₆), Cyclobutane (C₄H₈), Cyclopentane (C₅H₁₀), Cyclohexane (C₆H₁₂) etc.

Aromatic Compounds 🌸
These are the cyclic or Carbocyclic compounds containing one or more benzene rings (six carbon atoms with three alternating double bonds). e.g. benzene and naphthalene.

🍬 Carbohydrates & Biomolecules

Saccharides 🍞
Saccharides commonly known as carbohydrates defined as polyhydroxy aldehydes or ketones or large molecules that give these compounds on hydrolysis..

Aldoses 🍯
The carbohydrates or sugars containing an aldehyde (–CHO) functional group. e.g. Glucose, Ribose

Ketoses 🍬
The carbohydrates or sugars containing a ketonic (>C=O) functional group. e.g. Fructose, Ribulose

Glycosidic Linkage 🔗🍬
The bond linking monosaccharides in carbohydrates.

Nucleotide 🧬
The basic unit of nucleic acids made of sugar, base, and phosphate group.

🧠 Biochemistry & Biological Molecules

Biochemistry 🧬
It is the study of naturally occurring macromolecules and their chemical processes occurring in living organisms.

Enzymes ⚡
Enzymes are the class of proteins which are biocatalysts produced by living cells that speed up biochemical reactions.

Peptide Linkage 🔗
It is the acid-amide (–CO–NH–) bond linking amino acids in proteins by eliminating a water molecule. (A protein molecule formed with two amino acids is termed as dipeptide, with three tripeptide and so son. This linkage is formed by the removal of a water molecule b/w an NH₂ group of an amino acid and COOH group of another).

Lipids 🧈
Lipids are a group of naturally occurring heterogeneous water-insoluble non-polar organic compounds (like fats, oils, and waxes) of the plant and animal origins that are soluble in Bloor’s reagent and organic solvents.

Fatty Acids 🧪
Fatty acids are naturally long-chain aliphatic saturated or unsaturated carboxylic acids that form fats and oils containing even number of carbon atoms (ranges C₁₂-C₂₀). Fatty acids are building blocks of lipids. e.g. Palmitic acid; C₁₅H₃₁COOH, Stearic acid; C₁₇H₃₅COOH

Saponification 🧼
It is the conversion of fats or oils into soap using alkali. It is the reaction of triglycerides or fats or oils with sodium or potassium hydroxide to form glycerol and fatty acid salt called soap.

Bloor’s Reagent 🧴
It is a 2:1 mixture of diethyl ether and ethyl alcohol used to dissolve lipids.

🌍 Environmental Chemistry

Environmental Chemistry 🌎
Environmental Chemistry is the study of chemical and biological processes in air, water, and soil and human impact on them.

Ozone Hole 🕳️☀️
It is the region of severe depletion of ozone layer in the stratosphere.

📊 Analytical Chemistry & Measurement

Analytical Chemistry 🔍
It is the branch of chemistry concerned with separation, identification, and quantification of substances through various techniques and instruments.

Qualitative Analysis 🧾
It involves identification of components of elements, ions or compounds present in a sample focusing only its quality.

Quantitative Analysis ⚖️
It involves determination of the exact amount of substances present.

Accuracy 🎯
It is the closeness of a measured value to the true value of a sample.

Precision 📏
It is the closeness of repeated measurements of the same quantity to each other.

Parameter 🧠
It is a measurable factor used to validate analytical methods (accuracy, precision, linearity, etc.).

🧪 Chromatography & Instrumental Methods

Chromatography 🧫➡️
A separation technique based on different distribution of components between two phases.

Stationary Phase 🧱
The immobile phase in chromatography.

Mobile Phase 🚿
The moving phase that carries the sample.

Retention Time ⏱️
Time taken by a component to pass through the stationary phase.

Potentiometry 🔌
An analytical technique that measures electrode potential to determine concentration.

2️⃣

Write down three differences between any one of the following:

(i) Troposphere and Stratosphere
(ii) Reversible and irreversible reactions
(iii) Saturated and unsaturated hydrocarbons
(iv) Dextrorotary and Levorotatory Sugars
(v) Quantitative analysis and qualitative analysis
(vi) Titrimetric analysis and gravimetric analysis
(vii) Classical and Instrumental Methods
(viii) Fat and water-soluble vitamins
(ix) DNA and RNA
(x) Fat and oil
(xi) Aldoses and ketoses
(xii) Forward and reverse reactions

Answer

(i) 🌿 Saturated vs Unsaturated Hydrocarbons

🟢 Saturated
Contain only C–C single bonds 🔗

🔵 Unsaturated
Contain C=C or C≡C bonds ⚡

🟢 Have maximum hydrogen atoms 💧

🔵 Have fewer hydrogen atoms

🟢 Less chemically reactive 😌

🔵 More chemically reactive 🔥

🟢 Undergo substitution reactions 🔄

🔵 Undergo addition reactions ➕

🟢 More stable compounds 🧱

🔵 Less stable compounds ⚠️

🟢 Alkanes: CₙH₂ₙ₊₂ (e.g. ethane)

🔵 Alkenes: CₙH₂ₙ (e.g. ethene, propene), Alkynes: CₙH₂ₙ₋₂ (e.g. ethyne, propyne)

(ii) 🧈 Fat vs Oil

🧈 Fat
Solid at room temperature ❄️

🛢️ Oil
Liquid at room temperature 🌡️

🧈 Obtained mainly from animals 🐄

🛢️ Obtained mainly from plants 🌻

🧈 Saturated compounds/High degree of saturation 🔗

🛢️ Unsaturated compounds/High degree of unsaturation ⚡

🧈 Higher melting point 🔺

🛢️ Lower melting point 🔻

🧈 Increase cholesterol level ⚠️

🛢️ Help maintain cholesterol level ❤️

🧈 Mostly Triglycerides of saturated fatty acids

🛢️ Mostly Triglycerides of unsaturated fatty acids

🧈 No addition reaction. ❌

🛢️ Undergo addition reaction with H₂ ➕

(iii) 💊 Fat-soluble vs Water-soluble Vitamins

🧈 Fat-soluble
Soluble in fats & oils

💧 Water-soluble
Soluble in water

🧈 They include Vitamin A, D, E, K.

💧 They include Vitamin B-complex, Vitamin C

🧈 Absorbed in small intestine

💧 Absorbed in small intestine

🧈 Hydrophobic (water-repelling) 🚫💧

💧 Hydrophilic (water-loving) 💦

🧈 Stored in liver & tissues 🫀

💧 Not stored; excess excreted 🚽

🧈 Comparatively more toxic ⚠️

💧 Low toxicity

🧈 Deficiency develops slowly ⏳

💧 Deficiency develops quickly ⏱️

🧈 Require bile salts & fats for absorption

💧 Easily absorbed

(iv) 🔄 Dextrorotatory vs Levorotatory Sugars

➡️ Dextrorotatory
Rotate plane-polarized light right

⬅️ Levorotatory
Rotate plane-polarized light left

➡️ Clockwise rotation 🔁

⬅️ Anti-clockwise rotation 🔄

➡️ Represented by d or (+)

⬅️ Represented by l or (−)

(v) 📊 Quantitative vs Qualitative Analysis

⚖️ Quantitative
Deals with amount of substance 📊

🔍 Qualitative
Deals with nature of substance 🔬

⚖️ Gives numerical results 🔢

🔍 Gives descriptive results 📝

⚖️ Determines exact quantity 📏

🔍 Concerned with quality 🧪

⚖️ Uses titration, gravimetric methods, combustion analysis, etc.

🔍 Uses colour tests, flame tests, chromatography etc.

⚖️ Concerned with “how much”

🔍 Concerned with “what is present”

⚖️ Examples: Chemical analysis, Instrumental analysis, concentration determination

🔍 Examples: Elemental analysis (ion identification), Structural analysis

(vi) 🔁 Reversible vs Irreversible Reactions

🔄 Reversible
Occur in both forward & reverse directions

➡️ Irreversible
Occur in one direction only i.e. forward

🔄 Usually occur in closed system 🔒

➡️ Usually occur in open system

🔄 Attain dynamic equilibrium ⚖️

➡️ No equilibrium attained

🔄 Reaction does not go to completion

➡️ Reaction goes to completion ✅

🔄 Reactants not fully converted into products

➡️ Reactants almost fully converted into product

🔄 Represented by ⇌ (double half-headed arrow)

➡️ Represented by → (single-headed arrow)

🔄 Reactants & products coexist

➡️ Reactants mostly disappear

🔄 Examples: Esterification, Ammonia synthesis, Oxidation of SO₂ → SO₃

➡️ Examples: Neutralization, Precipitation, Hydrolysis reactions

(vii) 🧪 Classical vs Instrumental Methods ⚙️

🧪 Classical
Simple procedures

⚙️ Instrumental
Sensitive & technical procedures

🧪 Cheap equipment 💰

⚙️ Expensive instruments 💸

🧪 Based on absolute measurements

⚙️ Based on instrumental readings

🧪 No special training required

⚙️ Skilled training required 🎓

🧪 Accuracy decreases with less sample

⚙️ Accuracy depends on instrument

🧪 Slow determination ⏳

⚙️ Very fast determination ⚡

🧪 Large sample required

⚙️ Very small sample sufficient

🧪 Based on chemical reactions

⚙️ Based on instruments

🧪 Example: titration

⚙️ Example: spectrophotometry

(viii) 🌍 Troposphere vs Stratosphere

🌧️ Troposphere
Lowest layer of atmosphere

☀️ Stratosphere
Layer above the troposphere

🌧️ Height ~8–11 km

☀️ Extends up to ~50 km

🌧️ Contains ~75% atmospheric mass

☀️ Contains much less air

🌧️ Weather occurs here 🌦️

☀️ No weather phenomena

🌧️ Rich in water vapour and gases ☁️

☀️ Very low water vapour and gases

🌧️ Temperature decreases with height ❄️

☀️ Temperature increases with height 🔥

🌧️ Temp: 15°C to –56°C

☀️ Temp: –56°C to 2°C

🌧️ Ozone here is pollutant

☀️ Ozone layer protects from UV 🛡️

🌧️ High humidity

☀️ Very low humidity

🌧️ It has water vapours, clouds & dust particles

☀️ It lacks water vapours, clouds, and dust particles

🌧️ Strong air movement

☀️ Little air movement

🌧️ Humans live here 🧍‍♂️

☀️ Aircraft travel here ✈️

3️⃣

Define chemical equilibrium state with its any three macroscopic properties. Why chemical equilibrium is dynamic? Explain it with one example.

Answer

📖 Definition of Chemical Equilibrium
Chemical equilibrium is the state of a reversible reaction carried out in a closed system at which there is no observable change in the concentrations of reactants and products with time, because the rate of forward reaction is equal to the rate of reverse reaction.

At equilibrium:
➡️ Rate of forward reaction = Rate of backward reaction
➡️ Concentrations of reactants and products remain constant

📌 Macroscopic Properties of Chemical Equilibrium (Any three)

➡️ Initial concentrations do not affect the value of Kc 📉📈

➡️ Equilibrium attained only in closed system 🔒

➡️ Concentrations of reactants and products remain constant 📊

➡️ Properties like colour, pressure, density and pH remain constant ⚖️

➡️ Forward and reverse reactions continue simultaneously at equal rates 🔄

🔄 Chemical Equilibrium as Dynamic Equilibrium
Chemical equilibrium is dynamic because both forward and reverse reactions continue to occur at the same rate even after equilibrium is established.
Neither reaction stops; they occur continuously but at equal speed, so there is no net change in concentration.

🧪 Example: Formation of Hydrogen Iodide
H₂ (g) + I₂ (g) ⇌ 2HI (g)
➡️ Initially, the concentrations of H₂ and I₂ are high and HI is zero.
➡️ As the reaction proceeds, H₂ and I₂ decrease, and HI increases.
➡️ As HI accumulates, the reverse reaction starts.
➡️ The rate of forward reaction decreases while the reverse reaction increases.
➡️ Finally, both rates become equal and equilibrium is established.
➡️ Concentrations of H₂, I₂ and HI remain constant, though reactions continue.

OR

What is equilibrium constant? Write down any three characteristics of equilibrium constant. Why equilibrium constant may or may not have unit? Justify with example.

Answer

📖 Definition of Equilibrium Constant
The equilibrium constant (Kc) of a reversible reaction is the ratio of the product of equilibrium molar concentrations (active masses) of products to that of reactants, each raised to the power of their respective stoichiometric coefficients, at a constant temperature.

🧮 Mathematical Expression of Kc
For a general reversible reaction: aA + bB ⇌ cC + dD
Kc = [C]ᶜ [D]ᵈ / [A]ᵃ [B]ᵇ

⭐ Characteristics of Equilibrium Constant

➡️ Concentrations of reactants and products remain constant 📊

➡️ Physical properties (colour, pressure, density) remain constant ⚖️

➡️ Attained only in a closed system 🔒

➡️ Forward and reverse reactions occur simultaneously 🔄

➡️ The value of Kc depends only on temperature 🌡️

➡️ Indicates direction of reaction ➡️⬅️

📌 Importance of Kc
➡️ Helps predict extent of reaction.
➡️ Indicates position of equilibrium.
➡️ Useful in industrial and chemical calculations.

📐 Unit of Equilibrium Constant (Kc)
When the number of moles of gaseous reactants equals the number of moles of gaseous products, concentration units cancel out.
Example: CO(g) + H₂O(g) ⇌ CO₂(g) + H₂(g) → Kc has no unit.

When the number of moles of reactants and products are not equal, Kc has a unit.
Example: N₂(g) + 3H₂(g) ⇌ 2NH₃(g)
Reactants = 4 moles, Products = 2 moles
Kc = [NH₃]² / [N₂][H₂]³ = 1/[mol.dm⁻³]² → mol⁻² dm⁶

4️⃣

Write down Equilibrium Constant Expression (Kc) and unit of Kc for any 3 of the following balanced reversible reactions.
(i) N₂₍g₎ + 2O₂₍g₎ ⇌ 2NO₂₍g₎      (ii) H₂₍g₎ + I₂₍g₎ ⇌ 2HI₍g₎
(iii) CO₂₍g₎ + H₂₍g₎ ⇌ CO₍g₎ + H₂O₍g₎      (iv) 2SO₂₍g₎ + O₂₍g₎ ⇌ 2SO₃₍g₎
(v) N₂₍g₎ + 3H₂₍g₎ ⇌ 2NH₃₍g₎      (vi) CO₍g₎ + 3H₂₍g₎ ⇌ CH₄₍g₎ + H₂O₍g₎

Answer

(i) N₂₍g₎ + 2O₂₍g₎ ⇌ 2NO₂₍g₎

➡️ Kc = [NO₂]² / [N₂][O₂]²; ➡️ Unit of Kc = mol⁻¹ dm³

(ii) H₂₍g₎ + I₂₍g₎ ⇌ 2HI₍g₎

➡️ Kc = [HI]² / [H₂][I₂]; ➡️ Unit of Kc = No unit

(iii) CO₂₍g₎ + H₂₍g₎ ⇌ CO₍g₎ + H₂O₍g₎

➡️ Kc = [CO][H₂O] / [CO₂][H₂]; ➡️ Unit of Kc = No unit

(iv) 2SO₂₍g₎ + O₂₍g₎ ⇌ 2SO₃₍g₎

➡️ Kc = [SO₃]² / [SO₂]²[O₂]; ➡️ Unit of Kc = mol⁻¹ dm³

(v) N₂₍g₎ + 3H₂₍g₎ ⇌ 2NH₃₍g₎

➡️ Kc = [NH₃]² / [N₂][H₂]³; ➡️ Unit of Kc = mol⁻² dm⁶

(vi) CO₍g₎ + 3H₂₍g₎ ⇌ CH₄₍g₎ + H₂O₍g₎

➡️ Kc = [CH₄][H₂O] / [CO][H₂]³; ➡️ Unit of Kc = mol⁻² dm⁶

5️⃣

(a) What are conjugate acids and conjugate bases of each of the following?
HS⁻, H₃O⁺, H₂PO₄⁻, HSO₄⁻, HF, CH₃COOH, [Al(H₂O)₆]³⁺, OH⁻, HCO₃⁻, HPO₄²⁻, CH₃NH₂, CO₃²⁻

(b) Which of the following behave both as Bronsted acids and Bronsted bases?
H₂O, HCO₃⁻, H₂SO₄, H₃PO₄, HS⁻

Answer

🧪 5(a) Conjugate Acids and Conjugate Bases
Rule reminder 🔁
Conjugate acid → formed by adding H⁺
Conjugate base → formed by removing H⁺

⚡ HS⁻ ➡ Conjugate acid: H₂S ➕ ➡ Conjugate base: S²⁻ ➖
⚡ H₃O⁺ ➡ Conjugate acid: H₄O²⁺ ➕ ➡ Conjugate base: H₂O ➖
⚡ H₂PO₄⁻ ➡ Conjugate acid: H₃PO₄ ➕ ➡ Conjugate base: HPO₄²⁻ ➖
⚡ HSO₄⁻ ➡ Conjugate acid: H₂SO₄ ➕ ➡ Conjugate base: SO₄²⁻ ➖
⚡ HF ➡ Conjugate acid: H₂F⁺ ➕ ➡ Conjugate base: F⁻ ➖
⚡ CH₃COOH ➡ Conjugate acid: CH₃COOH₂⁺ ➕ ➡ Conjugate base: CH₃COO⁻ ➖
⚡ [Al(H₂O)₆]³⁺ ➡ Conjugate acid: [Al(H₂O)₆]⁴⁺ ➕ ➡ Conjugate base: [Al(H₂O)₅OH]²⁺ ➖
⚡ OH⁻ ➡ Conjugate acid: H₂O ➕ ➡ Conjugate base: O²⁻ ➖
⚡ HCO₃⁻ ➡ Conjugate acid: H₂CO₃ ➕ ➡ Conjugate base: CO₃²⁻ ➖
⚡ HPO₄²⁻ ➡ Conjugate acid: H₂PO₄⁻ ➕ ➡ Conjugate base: PO₄³⁻ ➖
⚡ CH₃NH₂ ➡ Conjugate acid: CH₃NH₃⁺ ➕ ➡ Conjugate base: CH₃NH⁻ ➖
⚡ CO₃²⁻ ➡ Conjugate acid: HCO₃⁻ ➕ ➡ Conjugate base: CO₃³⁻ ➖

🔄 5(b) Substances Acting as Both Brønsted Acid & Base (Amphoteric)
Amphoteric: H₂O 💧, HCO₃⁻ 🔁, HS⁻ ⚖️
Not amphoteric: H₂SO₄, H₃PO₄ ❌

OR

What are conjugate acid-base pairs? Also define conjugate acid and conjugate base. Identify acid, base, conjugate acid and conjugate base in the following reactions:
➡️ CH₃COOH + H₂O ⇌ H₃O⁺ + CH₃COO⁻
➡️ NH₃ + HCl ⇌ NH₄⁺ + Cl⁻
➡️ H₂O + NH₃ ⇌ NH₄⁺ + OH⁻

Answer

🔁 Conjugate Acid–Base Pairs: A conjugate acid–base pair consists of two species that differ by one proton (H⁺).
🛡️ Conjugate Acid: A conjugate acid is the species formed when a base accepts a proton (H⁺). ➕
📉 Conjugate Base: A conjugate base is the species formed when an acid donates a proton (H⁺). ➖

🧪 Identification in Given Reactions
(i) CH₃COOH (Acid 🍋) + H₂O (Base 💧) ⇌ H₃O⁺ (Conjugate acid) + CH₃COO⁻ (Conjugate base)
➡️ Conjugate pairs: CH₃COOH / CH₃COO⁻, H₂O / H₃O⁺

(ii) NH₃ (Base 🧪) + HCl (Acid 🍋) ⇌ NH₄⁺ (Conjugate acid) + Cl⁻ (Conjugate base)
➡️ Conjugate pairs: HCl / Cl⁻, NH₃ / NH₄⁺

(iii) H₂O (Acid 🍋) + NH₃ (Base 🧪) ⇌ NH₄⁺ (Conjugate acid) + OH⁻ (Conjugate base)
➡️ Conjugate pairs: H₂O / OH⁻, NH₃ / NH₄⁺

6️⃣

State vital force theory and how was this theory discarded by Wohler?

Answer

✨ Vital Force Theory ⚡
Proposed by Jacob Berzelius (1828) 🧪
Claimed organic compounds can only be made by living organisms under a “vital force” 🌱
Cannot be synthesized from inorganic substances ❌

✨ Disproof by Wohler ✅
In 1828, Friedrich Wöhler synthesized urea from ammonium cyanate in the lab 🏭
Showed organic compounds can be made artificially, discarding the theory 🌟
NH₄OCN (ammonium cyanate) — H₂O/Heat (Rearrangement) → (NH₂)₂CO (urea/carbamide)

OR

Write the names and structural formulae of six carbons alkanes, alkenes, alkyne, cycloalkane and aromatic hydrocarbons.

Answer

1️⃣ Alkane (C₆H₁₄) – Hexane ➡️ CH₃–CH₂–CH₂–CH₂–CH₂–CH₃
2️⃣ Alkene (C₆H₁₂) – Hex-1-ene ➡️ CH₂=CH–CH₂–CH₂–CH₂–CH₃
3️⃣ Alkyne (C₆H₁₀) – Hex-1-yne ➡️ CH≡C–CH₂–CH₂–CH₂–CH₃
4️⃣ Cycloalkane (C₆H₁₂) – Cyclohexane ➡️ (CH₂)₆ (ring)
5️⃣ Aromatic (C₆H₆) – Benzene ➡️ ⬡ (hexagonal ring with alternating double bonds)

OR

Draw the structures of following compounds:

Answer

(i) 2,3-Dimethylpentane ➡️ CH₃–CH(CH₃)–CH(CH₃)–CH₂–CH₃
(ii) 3-Ethyl-1-hexene ➡️ CH₂=CH–CH(C₂H₅)–CH₂–CH₂–CH₃
(iii) 2-Butyne ➡️ CH₃–C≡C–CH₃
(iv) 2,4-Hexadiene ➡️ CH₂=CH–CH=CH–CH₂–CH₃
(v) 3-Methyl-1,4-hexadiyne ➡️ CH≡C–CH(CH₃)–CH₂–C≡CH
(vi) 2-Hepten-5-yne ➡️ CH₃–CH=CH–CH₂–C≡C–CH₃
(vii) 2-Pentyne ➡️ CH₃–C≡C–CH₂–CH₃
(viii) Neopentane (2,2-dimethylpropane) ➡️ (CH₃)₄C
(ix) Iso-propyl alcohol ➡️ CH₃–CH(OH)–CH₃
(x) Phenol ➡️ C₆H₅–OH
(x) Toluene ➡️ C₆H₅–CH₃
(xi) Iso-butane (2-methylpropane) ➡️ (CH₃)₂CH–CH₃
(xii) Cyclohexane ➡️ (CH₂)₆ (ring)

7️⃣

Answer

📐 Definition of Structural Formula
A structural formula shows the arrangement of atoms and the bonds between them in a molecule.

1️⃣ Ethane
Molecular formula: C₂H₆
Structural formula: H–C–C–H (each C bonded to 3 H)
Condensed formula: CH₃–CH₃

2️⃣ Ethene
Molecular formula: C₂H₄
Structural formula: H₂C=CH₂
Condensed formula: CH₂=CH₂

3️⃣ Ethyne
Molecular formula: C₂H₂
Structural formula: HC≡CH
Condensed formula: HC≡CH

4️⃣ Ethyl alcohol
Molecular formula: C₂H₆O
Structural formula: H–C–C–OH (H₃C–CH₂–OH)
Condensed formula: CH₃–CH₂–OH

5️⃣ Acetic acid
Molecular formula: C₂H₄O₂
Structural formula: H–C–C(=O)–OH
Condensed formula: CH₃–COOH

6️⃣ Acetone
Molecular formula: C₃H₆O
Structural formula: H₃C–C(=O)–CH₃
Condensed formula: (CH₃)₂CO

7️⃣ n-Butane
Molecular formula: C₄H₁₀
Structural formula: CH₃–CH₂–CH₂–CH₃
Condensed formula: CH₃–CH₂–CH₂–CH₃

8️⃣ Isobutane
Molecular formula: C₄H₁₀
Structural formula: (CH₃)₃CH
Condensed formula: (CH₃)₃CH

9️⃣ Methyl acetate
Molecular formula: C₃H₆O₂
Structural formula: CH₃–COO–CH₃
Condensed formula: CH₃–COOCH₃

🔟 Dimethyl amine
Molecular formula: C₂H₇N
Structural formula: (CH₃)₂NH
Condensed formula: (CH₃)₂NH

OR
Define functional group. Identify the functional groups in the following compounds:

Answer

🧩 Functional Group
An atom or group of atoms or multiple bonds in an organic molecule responsible for its characteristic chemical reactions.

Compounds and their Functional Groups
(a) CH₃CHO – Aldehydic group –CHO 📝
(b) CH₃CH₂CH₂OH – Primary alcoholic group –OH 🍹
(c) CH₃COCH₃ – Ketonic carbonyl group –C=O ⚡
(d) C₃H₇COOH – Carboxylic acid –COOH 🧪
(e) CH₂=CHCH₃ – Double bond C=C 🔗
(f) CH₃OCH₃ – Ether –O– 🌬️
(g) CH₃CH₂COOCH₃ – Ester –COO– 🌸

8️⃣

Answer

🧂 Salt – Definition
A salt is an ionic crystalline compound formed by the neutralization of an acid and a base, consisting of a cation from the base (other than H⁺) and an anion from the acid (other than OH⁻).
Examples: NaCl, CuCl₂

🔖 Three Types of Salts
➡️ Normal Salts ⚖️ – Complete neutralization of acid and base. Examples: NaCl, KNO₃, K₃PO₄
➡️ Acidic Salts 🧪 – Partial neutralization of an acid. Examples: NaHCO₃, NaHSO₄, (NH₄Cl!)
➡️ Basic Salts 🧼 – Partial neutralization of a base. Examples: Mg(OH)Cl, (K₂CO₃!)

Uses of Salts
➡️ NH₄Cl, KCl
➡️ Pesticides 🐞 – e.g., copper(II) sulphate (CuSO₄), iron(II) sulphate (FeSO₄)
➡️ Medicines 💊 – FeSO₄·7H₂O (‘iron pills’) treats anemia
➡️ NaHCO₃ – Antacid to neutralize stomach acid 🧴
➡️ Potassium permanganate (KMnO₄) – Disinfectant to kill bacteria 🧼
➡️ CaSO₄·2H₂O – Plaster of Paris 🏥
➡️ BaSO₄ – X-ray contrast agent in barium meals 🩻

⚗️ Methods of Salt Preparation
Salts are prepared by the action of acids on metals, metal hydroxide (bases or alkalis), metal oxides, metal carbonates and metal bicarbonates. Salts are produced by the action of a base on a metal.

➡️ Acid + Metal → Salt + H₂
2HCl + Mg → MgCl₂ + H₂↑

➡️ Acid + Base → Salt + Water
HNO₃ + KOH → KNO₃ + H₂O
H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

➡️ Acid + Metal Oxide → Salt + Water
H₂SO₄ + CaO → CaSO₄ + H₂O

➡️ Acid + Carbonate → Salt + Water + CO₂
2HNO₃ + BaCO₃ → Ba(NO₃)₂ + H₂O + CO₂↑

Uses of Specific Salts
➡️ CuSO₄ – Fungicide/pesticide 🐛
➡️ CaSO₄ (dehydrated) – Plaster of Paris 🏥
➡️ FeSO₄·7H₂O – Treats anemia 💊
➡️ NaHCO₃ – Antacid 🧴
➡️ BaSO₄ – X-ray contrast agent 🩻
➡️ KMnO₄ – Disinfectant 🧼

OR
What are enzymes? Write one use of enzymes yeast, cellulase, lipase, lactase and amylase.

Answer

(i) Yeast is used in the fermentation of molasses and starch to make alcohol (Ethanol). 🍞
(ii) Cellulase is used in detergents to break down cellulose into water-soluble glucose 🧼
(iii) Amylase is used as a sweetener in cuisine as well as in the baking of bread 🍪

🧬 Enzymes
Enzymes are biological catalysts that speed up chemical reactions without being consumed.

Uses of Specific Enzymes
➡️ Yeast 🍞 – Ferments molasses or starch (sugars) to produce ethanol (alcohol)
➡️ Cellulase 🧼 – Breaks down cellulose into glucose; used in detergents
➡️ Amylase 🍪 – Converts starch into sugar; used in sweeteners and baking
➡️ Lipase 🥛 – Breaks down fats; used in detergents, cheese, and biodiesel
➡️ Lactase 🥛 – Breaks down lactose; used in lactose-free dairy products and supplements

OR
What is homologous series? Name the any two common homologous series with examples. Write down the general characteristics of homologous series. Write the possible isomers of Pentane with their common name and IUPAC name.

Answer

🧩 Homologous Series
A homologous series (Greek, homo means same and logous means ratio) is a family of similar organic compounds with the same functional group and similar chemical properties, where each successive member differs by methylene (–CH₂) group (14 amu by molecular mass). Each member is called a homologue.

🌟 Examples
Alkanes: Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈) ➡️ CₙH₂ₙ₊₂
Alkenes: Ethene (C₂H₄), Propene (C₃H₆) ➡️ CₙH₂ₙ
Alkynes: Ethyne (C₂H₂), Propyne (C₃H₄), Butyne (C₄H₆) ➡️ CₙH₂ₙ₋₂
Alkyl halides: Methyl halide (CH₃Cl), Ethyl halide (C₂H₅Cl) ➡️ CₙH₂ₙ₊₁X
Alcohols: Methyl alcohol (CH₃OH), Ethyl alcohol (C₂H₅OH) ➡️ CₙH₂ₙ₊₁OH

🔹 General Characteristics
➕ Successive members differ by –CH₂– (14 u)
🧮 General molecular formula: Alkanes: CₙH₂ₙ₊₂, Alkenes: CₙH₂ₙ, Alkynes: CₙH₂ₙ₋₂
⚗️ General method of preparation: Similar method for all members (e.g., reduction of alkyl halides for alkanes)
🔥 Identical chemical properties: Similar reactivity due to same functional group (e.g., alkanes → combustion, halogenation)

🧬 Isomers of Pentane
🧪 Pentane
📛 Common Name: n-Pentane 🧾 IUPAC Name: Pentane 🔗 Structure: CH₃–CH₂–CH₂–CH₂–CH₃

🧪 Isopentane
📛 Common Name: Isopentane 🧾 IUPAC Name: 2-Methylbutane 🔗 Structure: CH₃–CH(CH₃)–CH₂–CH₃

🧪 Neopentane
📛 Common Name: Neopentane 🧾 IUPAC Name: 2,2-Dimethylpropane 🔗 Structure: (CH₃)₄C

OR
What is alkyl radicals? Give its type formula and general formula. Explain with structure different radicals of butane. What is the difference of alkyl radicals obtained from propane?

Answer

🧬 Alkyl Radicals
Definition: Radicals obtained from alkanes by removing one hydrogen atom are called alkyl radicals or groups.
General symbol: R–
General formula: CₙH₂ₙ₊₁
Origin: R–H — –H → R– e.g. CH₄ — –H → CH₃

🔗 Butyl Radicals (from Butane, C₄H₁₀)
Formula: C₄H₉–
Total isomers: 4 (2 from n-butane + 2 from iso-butane)

From n-butane (CH₃–CH₂–CH₂–CH₃):
➡️ n-Butyl (1°) – H removed from terminal carbon → CH₃–CH₂–CH₂–CH₂–
➡️ sec-Butyl (2°) – H removed from central carbon → CH₃–CH–CH₂–CH₃

From iso-butane ((CH₃)₃CH):
➡️ iso-Butyl (1°) – H removed from terminal carbon → (CH₃)₂CH–CH₂–
➡️ tert-Butyl (3°) – H removed from central carbon → (CH₃)₃C–

🔄 Difference of Alkyl Radicals from Propane vs Butane
Propane gives 2 isomeric propyl radicals (C₃H₇–): n-propyl (1°) and isopropyl (2°).
➡️ n-Propyl (1°) – H removed from terminal carbon → CH₃–CH₂–CH₂–
➡️ Isopropyl (2°) – H removed from central carbon → CH₃–CH–(CH₃)–

Butane gives 4 isomers: n-butyl (1°), sec-butyl (2°), iso-butyl (1°), tert-butyl (3°).

9️⃣

Elaborate ionization equation of water. Explain in detail that how water ionization is related with pH of solution? Also define pH, pOH and neutralization. Prove pH + pOH = 14.

Answer

💧 Ionization of Water
Water is a neutral liquid with equal numbers of H⁺ and OH⁻ ions.
Water is a weak electrolyte because it ionizes slightly in a process called auto-ionization or self-ionization.
Ionization equation: H₂O ⇌ H⁺ + OH⁻ (auto-ionization equilibrium)

⚗️ Equilibrium constant (Kc) for auto-ionization of water:
Kc = [H⁺][OH⁻]/[H₂O]
Kc·[H₂O] = [H⁺][OH⁻] (∵ [H₂O] = constant)
Kw = [H⁺][OH⁻] = 1 × 10⁻¹⁴ mol² dm⁻⁶ at 25°C

⚖️ Neutral solution: [H⁺] = [OH⁻] = 1×10⁻⁷ M (for pure water at 25°C)
🍋 Acidic solution: [H⁺] > [OH⁻]
🧼 Basic solution: [H⁺] < [OH⁻]

📏 pH and pOH
pH: Negative logarithm of hydrogen ion concentration. pH = −log[H⁺]
pOH: Negative logarithm of hydroxide ion concentration. pOH = −log[OH⁻]

🔗 Relation between pH and pOH:
[H⁺][OH⁻] = Kw = 1 × 10⁻¹⁴
log[H⁺] + log[OH⁻] = log(1×10⁻¹⁴)
−log[H⁺] − log[OH⁻] = 14
✅ pH + pOH = 14

⚖️ Neutralization
Definition: Reaction between an acid and a base to form a salt and water.
Example: HCl + NaOH → NaCl + H₂O

OR
Define buffers. What is the composition of buffers? How are they prepared? Discuss its importance in our daily life.

Answer

🧪 Buffer Solution
A buffer is an aqueous solution that resists changes in pH upon addition of small amounts of acid or base.
It maintains a relatively stable pH and neutralizes added H⁺ or OH⁻ ions.
Factor: pH of a buffer is independent of ionic strength but depends on temperature.
Composition: A weak acid + its salt (conjugate base) or weak base + its salt (conjugate acid).

🧩 Types of Buffers / Composition
🍋 Acidic Buffer – Made from weak acid + its salt with strong base (conjugate base). Example: CH₃COOH + CH₃COONa
🧼 Basic Buffer – Made from weak base + its salt with strong acid (conjugate acid). Example: NH₃ + NH₄Cl

⚗️ Preparation of Buffers
Acidic buffer: Mix weak acid with its sodium/potassium salt in water.
Basic buffer: Mix weak base with its salt of strong acid in water.

🌟 Importance of Buffers
❤️ Blood pH maintenance – carbonate, phosphate, protein buffers
🔬 Laboratory reactions – maintain stable pH for experiments
🏭 Industries – leather tanning, sugar, paper, pharmaceuticals
🧫 Biological media – culture media for bacteria & viruses
🌾 Agriculture – improve crop yield
🍎 Food preservation – fruits, canned foods
🧬 Scientific research – molecular biology, microbiology, cell biology, soil science, clinical analysis

🔟

Write any three significant uses of Carbohydrates and lipids.

Answer

🌾 Uses of Carbohydrates
1️⃣ Energy Source ⚡ – Main source of energy for plants and animals.
2️⃣ Structural Support 🌱 – Provide structural support in plants.
3️⃣ Energy Storage 🔋 – Stored as starch (plants) and glucose/glycogen (animals).

🧈 Uses of Lipids
1️⃣ Nutrient Transport 🚚 – Carry fatty acids and vitamins A, D, E, K.
2️⃣ Enzyme Regulation ⚙️ – Help in activation and functioning of enzymes.
3️⃣ Cooking & Frying 🍳🔥 – Fats and oils are commonly used to cook and fry food, improving taste and texture.

OR
What are amino acids and peptide bond? How peptide bond is formed? Also explain dipeptides & tripeptides.

Answer

🧬 Amino Acids
Amino acids are the building blocks of proteins. They are bifunctional organic compounds containing an acidic carboxyl group (–COOH), a basic amino group (–NH₂), and a variable side chain (R) that differs for each amino acid.

✨ Composition:
🧪 Acidic –COOH group
🔬 Basic –NH₂ group
🌟 Unique side chain ‘R’

Structure: R–CH–(NH₂)–COOH

🔗 Peptide Bond
A peptide bond is an acid-amide linkage formed between amino acids with the loss of water, leading to protein formation on polymerization.

⚡ Formation of Peptide Bond:
Amino acid 1 –COOH + Amino acid 2 –NH₂ → Dipeptide + H₂O 💧

NH₂–CH(R)–COOH + H–NH–CH(R)–COOH – H₂O → NH₂–CH(R)–CO–NH–CH(R)–COOH

👯‍♂️ Dipeptides & Tripeptides
🧩 Dipeptide – protein with 2 amino acids
🧩🧩🧩 Tripeptide – protein with 3 amino acids

OR
Write down three characteristics of organic compounds.

Answer

🧬 Contain Carbon and Hydrogen – Most organic compounds are carbon-based and may also contain O, N, S, or halogens.
🔗 Covalent Bonding – Atoms are joined mainly by covalent bonds, not ionic bonds.
🔥 Low Melting & Boiling Points – Many are volatile and flammable due to weak intermolecular forces.

OR
Write down three uses of organic compounds.

Answer

🌿 Uses of Organic Compounds
🔥 Fuel – e.g., petrol, diesel, natural gas provide energy.
💊 Medicines – e.g., aspirin, antibiotics, vitamins.
🧵 Materials & Polymers – e.g., plastics, synthetic fibers, rubber.

1️⃣1️⃣

Answer

(i) Why Silicon compounds are lesser than Carbon compounds? 🪨
👉 Silicon forms fewer compounds because Si–Si bonds are weaker (200 kJ mol⁻¹) than C–C bonds (355 kJ mol⁻¹) and catenation is less than carbon. 🔗

(ii) Why pure water is considered a weak electrolyte? 💧
👉 Water ionizes slightly to form H⁺ and OH⁻ ions on auto-ionization due to strong hydrogen bonding. ⚡

(iii) Justify petroleum is ‘black gold’ 🛢️
👉 Crude oil is black, but refined products are valuable like gold due to fuels and chemicals. 💰

(iv) Why alkanes are saturated hydrocarbons? 🔥
👉 They have only C–C single bonds and max H atoms with complete saturation of carbon valencies, no addition possible. ✅

(v) Why water-soluble vitamins are not injurious? 🥤
👉 They dissolve in water and are excreted from the body, so excess is non-toxic. 🚽

(vi) Why greenhouse effect leads to global warming? 🌡️
👉 The greenhouse effect or quantity of CO₂ in the air has a direct relationship with global warming effect. CO₂ traps heat in the atmosphere, raising Earth’s average temperature. 🌍

(vii) Why water is a solvent? 💦
👉 Water is polar with ability to form hydrogen bonding (solvating tendency), dissolving many ionic and polar compounds. ⚗️

(viii) How vegetable oil is converted into ghee? 🧈
👉 Hydrogenation converts unsaturated vegetable oils into saturated fats by adding H₂ at 250–300°C in the presence of Ni or Pd catalyst. This is an addition reaction of oil with H₂ to form an adduct called fat.
Hydrogenation: Vegetable oil + H₂ — Ni/Pd catalyst/250–300°C → saturated fat (ghee). 🔥

(ix) Why chemical equilibrium is dynamic, not static? ⚖️
👉 At equilibrium, forward and reverse reactions occur continuously at equal rates with no net change, so the system appears constant but is actually dynamic. 🔄

(x) Why temperature on mountains is colder than sea level? 🏔️
👉 At higher altitudes, lower air pressure causes expansion and reduces heat retention leading to cooling of air, making mountains colder than sea level. ❄️

(xi) Why organic compounds have great diversity? 🌿
👉 Organic compounds are highly diverse due to carbon’s catenation, tetravalency, and ability to form multiple bonds and functional groups. 🔗

(xii) Why IR spectroscopy is more advantageous than UV-vis? 🔬
👉 IR identifies functional groups, while UV-vis only detects conjugated systems; IR is more specific for structure. IR spectroscopy is more useful than UV-Vis because it clearly identifies functional groups and helps in detailed structural analysis. 🧪

1️⃣2️⃣

Complete the following neutralization reactions between acids and bases.

Answer

⚖️ Neutralization Reactions
(i) Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
(ii) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
(iii) 3NaOH + H₃PO₄ → Na₃PO₄ + 3H₂O

OR
Define vitamin and complete the following chart.

Answer

🍎 Vitamin
A vitamin is an organic compound required in small amounts by the body for normal growth, development, and metabolism, which cannot be synthesized in sufficient quantity by the body and must be obtained from the diet.

🍊🥦 Vitamins Sources and Deficiency Diseases

🍏 Vitamin Name	🌱 Sources	⚠️ Deficiency Disease
Vitamin A 🥕👁️	Butter, fish, eggs, milk, cheese, green & yellow vegetables, carrots, liver	Night blindness, xerophthalmia, dryness of skin
Vitamin D ☀️🦴	Fish liver, dairy products, mushrooms, oils/fats, formed in skin by sunlight	Rickets
Vitamin E 🥜🌿	Plant oils (wheat germ, cotton seed, corn germ, soybean, peanut), green leafy vegetables	Sterility, haemolysis
Vitamin K 🥬🩸	Green vegetables (spinach, alfalfa, cabbage), cereals	Haemorrhage
Vitamin C 🍊🛡️	Oranges, lemons, tomatoes, green peppers	Scurvy

1️⃣3️⃣

What are Oligosaccharides, Disaccharides and Polysaccharides. Give their examples and sources.

Answer

🍞🥔 Carbohydrates: Oligosaccharides, Disaccharides & Polysaccharides

1️⃣ Oligosaccharides (Oligo = few)
Definition: Carbohydrates that give 2–10 monosaccharide units on hydrolysis, linked by glycosidic bonds.
Properties: White, crystalline, sweet, water-soluble; may be reducing or non-reducing.
Types: Disaccharides, trisaccharides, tetrasaccharides, etc.

2️⃣ Disaccharides
Definition: Oligosaccharides with 2 monosaccharide units.
Hydrolysis: Produces two monosaccharides (e.g., sucrose → glucose + fructose).
Examples: Sucrose, maltose, lactose (milk sugar).
Sources: Sugarcane, sugar beet, milk, cereals.

3️⃣ Polysaccharides (Poly = many)
Definition: Macromolecular carbohydrates giving >10 monosaccharides on hydrolysis; made of hundreds–thousands of units linked by glycosidic bonds.
Properties: Amorphous, tasteless, insoluble in water, generally non-reducing.
Examples & Sources:
🌿 Cellulose: Plant cell walls, wood, cotton, paper; cotton ~95% cellulose.
🌾 Starch: Cereals (wheat, rice, barley), potato roots.
🐄 Glycogen: Animal starch in muscles & liver.
🍚 Amylose: Component of starch.

OR
What are the carbohydrates? Explain sources and types of carbohydrates.

Answer

🍞🍚 Carbohydrates
Definition: Carbohydrates are organic compounds containing C, H, O in ratio of 2:1 (like H₂O) and are polyhydroxy aldehydes or ketones, or compounds giving these on hydrolysis.
General formula: Cₙ(H₂O)ₙ

🔹 Types of Carbohydrates (Based on Hydrolysis)

1️⃣ Monosaccharides (Mono = one)
Definition: Simplest sugars that cannot be hydrolyzed further.
Hydrolysis: Non-hydrolyzable.
Carbon atoms: 3–10 (trioses, tetroses, pentoses, hexoses, etc.)
Properties: White, crystalline, sweet, water-soluble, reducing sugars.
Examples:
⚡ Glucose (C₆H₁₂O₆): Aldohexose, found in grapes, honey, cane sugar; blood sugar; rapid energy source.
⚡ Fructose (C₆H₁₂O₆): Ketohexose, found in fruits, honey, cane sugar.

2️⃣ Oligosaccharides (Oligo = few)
Definition: Carbohydrates giving 2–10 monosaccharides on hydrolysis, linked by glycosidic bonds.
Properties: White, crystalline, sweet, water-soluble; may be reducing or non-reducing.
Types: Disaccharides, trisaccharides, tetrasaccharides, etc.

2️⃣ Disaccharides
Definition: Oligosaccharides with 2 monosaccharide units.
Hydrolysis: Produces two monosaccharides (e.g., sucrose → glucose + fructose).
Examples: Sucrose, maltose, lactose.
Sources: Sugarcane, sugar beet, milk, cereals.

3️⃣ Polysaccharides (Poly = many)
Definition: Macromolecular carbohydrates giving >10 monosaccharides on hydrolysis.
Properties: Amorphous, tasteless, insoluble in water, generally non-reducing.
Examples & Sources:
🌿 Cellulose: Plant cell walls, cotton.
🌾 Starch: Cereals (wheat, barley), potato.
🐄 Glycogen: Liver & muscles.
🍚 Amylose: Component of starch.

🌱 Sources of Carbohydrates
📌 Monosaccharides 🍇🍯 – Glucose, Fructose: Grapes, honey, molasses, guava
📌 Oligosaccharides 🍬 – Sucrose: Sugarcane, beetroot, carrots, pineapple; Lactose: Milk 🥛; Maltose: Wheat 🌾, barley 🌾; Raffinose: Legumes
📌 Polysaccharides 🌿 – Cellulose: Plant cell walls, cotton 🏵️; Starch: Cereals, potato 🥔; Glycogen: Liver & muscles 🐄

1️⃣4️⃣

What are amino acids and give their general structure? How many Essential and Non-essential Amino Acids are there? Write down the range of Number of Amino Acids and molecular weights of Proteins.

Answer

🧬 Definition of Amino Acids
Amino acids are the building blocks of proteins. They are bifunctional organic compounds containing an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen atom, and a variable side chain (R group) attached to the same carbon atom.

📐 General Structure
H₂N – CH(R) – COOH

Where:
–NH₂ = Amino group 🔬
–COOH = Carboxyl group 🧪
R = Variable side chain ✨
Central carbon = α-carbon ⚛️

🔢 Number of Amino Acids in Proteins: 60 – 6000
⚖️ Molecular weight of proteins: 43,000 – 50,000,000 daltons (1 dalton (Da) = 1 amu).
🧩 Total Amino Acids: 20
🌟 Essential Amino Acids: 10
🌱 Non-essential Amino Acids: 10

OR

What are fatty acids? Give their examples and chemical nature.

Answer

🛢️ Definition of Fatty Acids
Fatty acids are building blocks of lipids. Fatty acids are long-chain saturated or unsaturated carboxylic acids that combine with glycerol to form fats and oils (triesters).

🌟 Examples
Palmitic acid: C₁₅H₃₁COOH (Saturated fatty acid)
Stearic acid: C₁₇H₃₅COOH (Saturated fatty acid)

⚗️ Chemical Nature
Lipids are macromolecules composed of fatty acids. They include oils and fats, which are triesters of glycerol and three long-chain fatty acids. Because they contain three fatty acids, they are called triglycerides or triesters.

Triglycerides = Glycerol + 3 fatty acids → triesters (oils/fats). 🧈

1️⃣5️⃣

Briefly describe any three beneficial impacts of pharmaceutical industry on human society.

Answer

💊 Beneficial Impacts of Pharmaceutical Industry
⏳ Increases life expectancy – Medicines and therapies help people live longer and healthier lives.
🌍 Eradicates and controls diseases – Aims to eliminate diseases like smallpox and control epidemics globally.
😌 Reduces pain and suffering – Provides relief from chronic pain, improving quality of life and mental health.

OR

Give general formula for Alkanes, Alkenes and Alkynes. Identify Alkanes, Alkenes, Alkynes, Cycloalkanes and Aromatics in each of the following.
C₆H₆, C₂H₄, C₃H₄, C₃H₈, C₆H₁₂, C₅H₈, C₄H₆, C₆H₅OH

Answer

⚡ General Formulas
🔗 Alkanes: CₙH₂ₙ₊₂
🔗 Alkenes: CₙH₂ₙ
🔗 Alkynes: CₙH₂ₙ₋₂

🧪 Compound Identification
⚡ C₆H₆: Aromatic (Benzene) 🌸
⚡ C₂H₄: Alkene (Ethene) 🌱
⚡ C₃H₄: Alkyne (Propyne) 🔥
⚡ C₃H₈: Alkane (Propane) 💨
⚡ C₆H₁₂: Cycloalkane/Alkene (Cyclohexane / Hexene) 🔄
⚡ C₅H₈: Alkyne/Cycloalkene (Pentyne / Cyclopentyne) 🧬
⚡ C₄H₆: Alkyne/Cycloalkene (Butyne / Cyclopentene) 🧩
⚡ C₆H₅OH: Aromatic alcohol (Phenol) 💧

1️⃣6️⃣

Write down causes of following diseases:
(i) Diarrheal Diseases (ii) Dysentery (iii) Cholera (iv) Cryptosporidium
(v) Fluorosis (vi) Hepatitis (vii) Hookworm (viii) Typhoid

Answer

🌡️ Water-borne Diseases and Causes
💧 Diarrheal Diseases: Caused by viruses, bacteria, and parasites.
🦠 Dysentery: Caused by bacteria (Shigella, Salmonella, E. coli) or parasites (Entamoeba histolytica, Balantidium coli).
💧 Cholera: Caused by bacteria Vibrio cholerae.
🧫 Cryptosporidium: Caused by waterborne protozoan microbes.
⚠️ Fluorosis: Caused by accumulation of excess fluoride in the body.
🩺 Hepatitis: Caused by viruses (Hepatitis A, B, C, D, E).
🪱 Hookworm: Caused by parasitic hookworms.
🍽️ Typhoid: Caused by bacteria Salmonella typhi.
🟡 Jaundice: Caused by Hepatitis viruses A, B, C, D, E.

OR

Define atmosphere. Discuss its composition. Write down the names of different atmospheric layers with their altitude and temperatures.

Answer

🌍 Definition of Atmosphere
The atmosphere is a layer of gases that surrounds the Earth, held in place by gravity. It is essential for sustaining life as it provides oxygen for respiration, protects from harmful solar radiation, and regulates the climate.

🌬️ Composition of Atmosphere
Nitrogen (N₂) – 78.09%
Oxygen (O₂) – 20.95%
Argon (Ar) – 0.93%
Carbon Dioxide (CO₂) – 0.04% (variable)
Neon (Ne) – 0.0018%
Helium (He) – 0.0005%
Methane (CH₄) – Trace
Water Vapor (H₂O) – 0–4% (varies)
Other gases – Includes ozone (O₃), hydrogen (H₂), and xenon (Xe)

🌤️ Atmospheric Layers
🌦️ Troposphere: Altitude 0–8/15 km, Temperature decreases with altitude (up to –60°C).
🌈 Stratosphere: Altitude 8–15 km to ~50 km, Temperature increases with altitude (up to 0°C) due to ozone absorption of UV radiation.
🌙 Mesosphere: Altitude 50–85 km, Temperature decreases with altitude (as low as –90°C).
🔥 Thermosphere: Altitude 85–600 km, Temperature increases with altitude (up to 2,500°C or more).
🌌 Exosphere: Altitude 600–10,000 km, Temperature very high, can reach up to 2,500°C.

1️⃣7️⃣

What is the cause of acid rain? Explain. Write down the effects of acid rain and global warming.

Answer

🌧️⚠️ Definition
Acid rain occurs when pollutants like SO₂ and NO₂ react with rainwater to form sulfuric and nitric acids, lowering pH below 5.5. It is a harmful effect of air pollution 🌍💨.

🌧️ Cause of Acid Rain
Acid rain is formed when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) from burning fossil fuels mix with rainwater, creating sulfuric acid (H₂SO₄) and nitric acid (HNO₃), lowering the pH of rain below 5.5.

🌍 Effects of Acid Rain
🏛️ Buildings & Monuments: Erodes marble and limestone, causing deterioration.
🐟 Aquatic Life: Pollutes water with heavy metals, suffocating fish.
🌱 Plants: Damages leaves, reduces growth, and weakens resistance to cold and disease.
🌾 Soil: Increases soil acidity, affecting crop growth and leaching toxic metals.

🌎 Global Warming
Increased CO₂ leads to higher temperatures, melting ice, and extreme weather, compounding acid rain's damage to the environment.

OR

Give difference between primary and secondary air pollutants. Identify as primary or secondary air pollutant SO₂, CH₄, HNO₃, NH₃, H₂SO₄ and O₃.

Answer

🌬️ Primary vs. Secondary Air Pollutants

🟢 Primary Pollutants
👉 Directly emitted into the atmosphere.
Examples: CO₂, SO₂, NOx, CH₄, NH₃.

🔵 Secondary Pollutants
👉 Formed by chemical reactions of primary pollutants in the atmosphere.
Examples: H₂SO₄, O₃, HNO₃, PAN.

🔍 Identification
🟢 SO₂ – Primary pollutant
🟢 CH₄ – Primary pollutant
🔵 HNO₃ – Secondary pollutant
🟢 NH₃ – Primary pollutant
🔵 H₂SO₄ – Secondary pollutant
🔵 O₃ – Secondary pollutant

1️⃣8️⃣

Describe the composition of water. Write degree of Hardness of water on the basis of Dissolved Ca Ions (mg/L).

Answer

🌊 Water is a polar covalent molecule (H₂O) where the oxygen attracts electrons more than hydrogen, giving δ− on O and δ+ on H, making the molecule polar.

💧 Degree of Hardness of Water on the Basis of Dissolved Ca Ions (mg/L)
💦 Soft water → 0 – 16.1 mg/L
🙂 Slightly hard water → 16.1 – 60 mg/L
😐 Moderately hard water → 61 – 120 mg/L
🪨 Hard water → 121 – 180 mg/L
🔴 Very hard water → > 180 mg/L

1️⃣9️⃣

List down the applications of conductometry?

Answer

⚡ Applications of Conductometry
1️⃣ Degree of Dissociation 🧪 – Determine dissociation constant.
2️⃣ Solubility 🌡️ – Measure solubility of sparingly soluble substances.
3️⃣ Reaction Rate ⏱️ – Study rate constant of a reaction.
4️⃣ Titration Endpoint 🎯 – Detect end point of titrations.

OR
Define qualitative analysis. What are organic and inorganic qualitative analyses. Give their examples.

Answer

📝 Qualitative Analysis
✨ Definition: Identification of elements, ions, or compounds present in a sample — focusing on their presence (quality), not quantity. 🔍⚗️
Qualitative analysis is further divided into following types based on chemical tests:

🧪 Types
🔎 Inorganic Qualitative Analysis
🔬 Deals with ions (elements) and inorganic compounds using chemical tests ⚡🧂. Often involves precipitation, flame tests, or chemical reactions.
➡️ Example: Flame test of copper halides shows bluish green colour due to copper presence; Detection of Na⁺, K⁺, Cl⁻, SO₄²⁻.

🔎 Organic Qualitative Analysis
🧪 Identifies classes of organic compounds or functional groups through characteristic colour changes. 🌿🧬
➡️ Example: A white precipitate forms when silver nitrate (AgNO₃) in dilute nitric acid (HNO₃) is added, indicating halide ions (F, Cl, Br, I); Identification of carbohydrates, proteins, fats.

2️⃣ Inorganic Qualitative Analysis
Deals with identifying elements, ions, or simple inorganic compounds.
Examples:
⚡ Identification of cations like Na⁺, Ca²⁺, Fe³⁺.
⚡ Identification of anions like Cl⁻, SO₄²⁻, NO₃⁻.

2️⃣0️⃣

What is error? Write down causes of errors with their %. Write down brief note systematic and random errors with two examples each.

✅ Answer

❌ Error: The numerical difference between observed value and true value.

⚡ Causes of Errors
➡️ 13% Equipment failure ⚙️
➡️ 13% Human error 👩‍🔬
➡️ 16% Sample preparation 🧪
➡️ 10% Wrong calibration 📏

📊 Types of Errors
(i) Systematic error 🔧
(ii) Random error 🎲

🔧 Systematic Errors / Determinate Errors
➡️ Caused by defects in analytical method or improper functioning of instruments.
➡️ Types: instrumental, observational, environmental, theoretical.

📌 Examples:
1️⃣ Thermometer, pipette, burette, analytical balance showing consistent measurement error. 🌡️
2️⃣ Acid base titration with improperly prepared pH indicator or unclean burette causing early colour change. ⚗️

🎲 Random Errors / Indeterminate Errors
➡️ Caused by variations in procedure, environment, or instrument limitations.
➡️ Unavoidable, may be positive or negative.

📌 Examples:
1️⃣ Measuring mass on analytical balance gives varying readings due to air or moisture effects. ⚖️
2️⃣ Reading burette volume only to nearest 0.1 cm³ introduces unavoidable variation. 📏

🔎 Random errors are reduced by taking multiple readings and averaging results.

OR

Define quantitative analysis. What are the physical and chemical methods of quantitative analysis?

Answer

📝 Quantitative Analysis
✨ Determines the exact amount or concentration of one or more substances in a sample.

🌈 Physical Methods
📊 Measure physical properties such as density, temperature, light absorption, magnetic influences, colour, and texture.
➡️ Techniques: FTIR, AES, trace element analysis, EDS.

🌈 Chemical Methods
⚗️ Use chemical reactions (precipitation, oxidation, neutralization) to determine amounts.
➡️ Techniques: Volumetric analysis, Gravimetric analysis, Combustion analysis.

OR

What is vitamin D? Give its sources and importance.

Answer

☀️ Vitamin D
Definition: A fat-soluble vitamin essential for healthy bones and immunity 🦴🛡️.

🌱🐟🥛 Sources:
☀️ Sunlight
🐟 Fish
🥛 Milk & dairy

💡 Importance:
🦴 Strengthens bones & teeth
🛡️ Supports immune system
🥛 Helps in calcium absorption

Short Answer Questions

✏️ Smart Answers of Section-C (Long-Answer Questions) ✏️

2️⃣1️⃣

State law of mass action and define Kc. Derive an expression for equilibrium constant for a general reaction. Predict, which system at equilibrium, will contain maximum amount of reactant or maximum amount of product:
(i) 2CO₂ ⇌ 2CO + O₂ Kc = 3.1 ×10⁻¹⁸ mol.dm⁻³
(ii) 2O₃ ⇌ 3O₂ Kc = 5.9 ×10⁵⁵ mol.dm⁻³

Answer

📘 Statement of Law of Mass Action (LMA)
At constant temperature, the rate of a chemical reaction is directly proportional to the product of the active masses (molar concentrations) of the reactants, each raised to the power of their stoichiometric coefficients.
➡️ Rate ∝ Active mass of reactants
➡️ Active mass = molar concentration (mol dm⁻³)

👉 Definition of Kc
Kc is the ratio of the product of molar concentrations of products to that of reactants, each raised to the power of their stoichiometric coefficients, at equilibrium and constant temperature.

📗 Derivation of Equilibrium Constant (Kc)
Consider a general reversible reaction:
aA + bB ⇌ cC + dD

➡️ Rate of forward reaction ∝ [A]ᵃ [B]ᵇ OR Rᵳ = Kᵳ [A]ᵃ [B]ᵇ (Kᵳ = specific rate constant for forward reaction)
➡️ Rate of reverse reaction ∝ [C]ᶜ [D]ᵈ OR Rᵣ = Kᵣ [C]ᶜ [D]ᵈ (Kᵣ = specific rate constant for reverse reaction)

At equilibrium:
Rᵳ = Rᵣ
Kᵳ [A]ᵃ [B]ᵇ = Kᵣ [C]ᶜ [D]ᵈ
Kᵳ/Kᵣ = [C]ᶜ [D]ᵈ / [A]ᵃ [B]ᵇ

✅ Kc = Kᵳ/Kᵣ = [C]ᶜ [D]ᵈ / [A]ᵃ [B]ᵇ
Or simply: Kc = [Products]/[Reactants]

📊 Prediction of Reactant or Product Amount
🔎 Rule:
➡️ If Kc >> 1 → Products are favored ✅
➡️ If Kc << 1 → Reactants are favored ✅

(i) 2CO₂ ⇌ 2CO + O₂
Kc = 3.1 ×10⁻¹⁸ mol.dm⁻³
Since Kc is extremely small (<<1):
👉 Reaction favors reactants
👉 System contains maximum amount of CO₂ 🌫️

(ii) 2O₃ ⇌ 3O₂
Kc = 5.9 ×10⁵⁵ mol.dm⁻³
Since Kc is extremely large (>>1):
👉 Reaction favors products
👉 System contains maximum amount of O₂ 🌬️

2️⃣2️⃣

Answer

📘 Brønsted–Lowry Acid–Base Theory (1923)
Proposed by Johannes Brønsted and Thomas Lowry.

🔹 Definitions
👉 Acid → A substance (molecule or ion) that donates a proton (H⁺). Acid = Proton donor
👉 Base → A substance (molecule or ion) that accepts a proton (H⁺). Base = Proton acceptor

✅ Example:
HCl + NH₃ → NH₄⁺ + Cl⁻
HCl donates H⁺ → Acid
NH₃ accepts H⁺ → Base

🔁 Conjugate Acid–Base Pair
A conjugate acid–base pair consists of two species that differ by one proton (H⁺).
➡️ When an acid loses H⁺, it forms its conjugate base.
➡️ When a base gains H⁺, it forms its conjugate acid.

✅ Example:
HCl + H₂O ⇌ H₃O⁺ + Cl⁻
HCl → Acid
Cl⁻ → Conjugate base
H₂O → Base
H₃O⁺ → Conjugate acid

💧 Water is Both Bronsted-Lowry Acid and Base (Amphoteric Nature)
Water can act as both Brønsted acid and base depending on the reaction.

1️⃣ Water as a Base:
HCl + H₂O ⇌ H₃O⁺ + Cl⁻
HCl donates H⁺ → Acid
H₂O accepts H⁺ → Base
Forms H₃O⁺ (hydronium ion)

2️⃣ Water as an Acid:
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
NH₃ accepts H⁺ → Base
H₂O donates H⁺ → Acid
Forms OH⁻ ion
👉 Therefore, water is amphoteric ✅

📗 Lewis Concept of Acids and Bases (1923)
Proposed by G. N. Lewis.

🔹 Definitions
👉 Lewis Acid → Electron pair acceptor
👉 Lewis Base → Electron pair donor
👉 No need for H⁺ in Lewis theory

✅ Example 1:
H⁺ + H₂O → H₃O⁺
H⁺ accepts electron pair → Lewis acid
H₂O donates electron pair → Lewis base

✅ Example 2:
NH₃ + BF₃ → NH₃→BF₃
NH₃ donates lone pair → Lewis base
BF₃ accepts lone pair → Lewis acid
Forms coordinate covalent bond

⚠ Limitations of Brønsted–Lowry Theory
1️⃣ Only explains reactions involving proton (H⁺) transfer.
2️⃣ Cannot explain acid–base reactions without H⁺ (e.g., BF₃ + NH₃).
3️⃣ Does not explain acidic behavior of some non-protonic substances (like AlCl₃, SO₂, SO₃, CO₂). ❌
4️⃣ Does not describe strength based on electron pair acceptance.
5️⃣ Cannot explain basicity of OH⁻ compounds like NaOH, KOH 🧪.
6️⃣ Proton donor & acceptor must co-exist, but many reactions don’t follow this 🌀.

OR
State three different theories about concepts of acids and bases with one example and also indicate one limitation of each concept. Which of the following is/are Arrhenius acids and bases?
(a) Ca(OH)₂ (b) HNO₃ (c) NaOH (d) H₂SO₄ (e) KOH

Answer

📘 Three Theories of Acids and Bases

1️⃣ Arrhenius Theory (1887)
🔹 Definition:
👉 Arrhenius Acid → Produces H⁺ (or H₃O⁺) in aqueous solution.
👉 Arrhenius Base → Produces OH⁻ in aqueous solution.

✅ Example:
HNO₃(aq) → H⁺(aq) + NO₃⁻(aq)
NaOH(aq) → Na⁺(aq) + OH⁻(aq)

⚠ Limitation:
🌊 Only valid in aqueous solutions.
❌ Doesn’t explain ammonia’s basicity & CO₂’s acidity.
🧪 H⁺ ions react with water to form H₃O⁺.

2️⃣ Brønsted–Lowry Theory (1923)
🔹 Definition:
👉 Acid → Proton (H⁺) donor
👉 Base → Proton (H⁺) acceptor

✅ Example:
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
H₂O donates H⁺ → Acid
NH₃ accepts H⁺ → Base

⚠ Limitation:
Explains only proton-transfer reactions (cannot explain reactions without H⁺ like BF₃ + NH₃).

3️⃣ Lewis Theory (1923)
🔹 Definition:
👉 Lewis Acid → Electron pair acceptor
👉 Lewis Base → Electron pair donor
👉 No need for H⁺ in Lewis theory.

✅ Example:
NH₃ + BF₃ → NH₃→BF₃
NH₃ donates lone pair → Lewis base
BF₃ accepts lone pair → Lewis acid

⚠ Limitation:
Too broad; does not clearly distinguish between acid–base and other chemical reactions.

📝 Which of the Following are Arrhenius Acids and Bases?
✅ Arrhenius Acids (produce H⁺ in water): HNO₃, H₂SO₄
✅ Arrhenius Bases (produce OH⁻ in water): Ca(OH)₂, NaOH, KOH

2️⃣3️⃣

Define functional group. Write different functional groups which contain carbon, hydrogen and oxygen.

Answer

📘 Definition
An atom or group of atoms or multiple bonds whose existence in an organic compound gives distinctive qualities to that compound is called a functional group.

📗 Functional Groups Containing Carbon, Hydrogen and Oxygen
The organic compounds containing carbon, hydrogen and oxygen as functional groups are alcohols, ethers, aldehydes, ketones, carboxylic acids and esters.

⚡ Functional Group	📛 Name of F.G	📐 General Formula	📘 Class Formula	🏷️ Class Name	🧪 Examples
–OH	Hydroxyl	C_nH_2n+1–OH	R–OH	Alcohol	CH₃OH, C₂H₅OH
–CH₂–OH	Primary	C_nH_2n+1–OH	RCH₂–OH	Primary Alcohol	CH₃OH, C₂H₅OH
>CH–OH	Secondary	C_nH_2n+1–OH	R₂CH–OH	Secondary Alcohol	(CH₃)₂CHOH
>C–OH	Tertiary	C_nH_2n+1–OH	R₃C–OH	Tertiary Alcohol	(CH₃)₃COH
–O–	Ether linkage	C_nH_2n+1–OR	R–O–Rʹ	Ether	CH₃–O–CH₃
–CHO	Aldehydic	C_nH_2n+1–CHO	R–CHO	Aldehydes	H–CHO, CH₃–CHO
–COR	Keto	C_nH_2n+1–COR	R–CO–Rʹ	Ketones	CH₃–CO–CH₃
–COOH	Carboxylic	C_nH_2n+1–COOH	R–COOH	Carboxylic acid	H–COOH, CH₃–COOH
–COOR	Ester	C_nH_2n+1–COOR	Rʹ–COO–R	Ester	CH₃–CO–OCH₃

OR

Define nomenclature and describe IUPAC nomenclature rules for alkynes and alkanes. Write down IUPAC names of following:

Answer

📘 Definition of Nomenclature
Nomenclature is the process of naming chemical compounds using systematic rules so that each compound has a unique and recognizable name.

📗 IUPAC Nomenclature
The International Union of Pure and Applied Chemistry (IUPAC) developed a standardized system (Prefix–Parent–Suffix) to name organic compounds.

🔹 Parts of IUPAC Name
1️⃣ Root/Parent Hydrocarbon → Number of carbons
2️⃣ Suffix → Functional group/family
3️⃣ Prefix → Substituents

📘 Rules for Naming Alkanes
1️⃣ Longest Chain Rule – Select longest continuous chain, add suffix “–ane”.
2️⃣ Lowest Number Rule – Number from end nearest substituent.
3️⃣ Prefix with Position – Write substituent with its carbon number.
4️⃣ One Word Name – Use hyphens (–) and commas (,).
5️⃣ Multiplicity – Use di, tri, tetra for repeated substituents.
6️⃣ Alphabetical Order – Arrange substituents alphabetically.
7️⃣ Larger Radical Preference – Number from end nearer larger substituent.

📘 Rules for Naming Alkynes
1️⃣ Longest Chain Rule – Select chain with triple bond, suffix “–yne”.
2️⃣ Lowest Number Rule – Number from end nearest triple bond.
3️⃣ One Word Name – Mention position of triple bond.
4️⃣ Alkadiyne – Use di, tri, tetra for multiple triple bonds.
5️⃣ Double Bond Preference – Double bond gets priority if at same location.
6️⃣ Lowest Number Rule – If both double & triple bonds present, start from nearest bond.

📝 IUPAC Names of Given Compounds

2️⃣4️⃣

What are the main sources of organic compounds? Mention with special reference of coal, petroleum and natural gas.

Answer

📘 Sources of Organic Compounds
There are two principal natural sources of organic compounds: living organisms and minerals (coal, petroleum, natural gas).

🐄 Animals
Proteins (eggs, meat, fish), fats (milk, butter, cheese), vitamins, hormones, urea, uric acid.

🌱 Plants
Carbohydrates (sugars, starch, cellulose), proteins (pulses, beans), oils (sunflower, olive, soybean), vitamins (fruits), gums, rubbers, dyes, drugs, fibres (cotton), organic acids (citric, oxalic, tartaric).

🪨 1. Coal
Coal = “Black Gold”, a solid fossil fuel mainly carbon with O, H, N, S.
🔹 Formation: From dead plants buried millions of years ago → peat → coal (carbonization under high pressure & temperature).
🔹 Types: Five forms depending on carbon content, volatile matter, moisture.

🔥 2. Natural Gas
Mixture of hydrocarbons (mainly methane ~85%). Origin similar to coal/petroleum.
🔹 Occurrence: Found at Sui (Pakistan).
🔹 Formation: Decay of dead animal matter, usually above petroleum deposits.
🔹 Uses:
1️⃣ Domestic & industrial fuel.
2️⃣ Fertilizer (urea).
3️⃣ Automobile fuel (CNG).
4️⃣ Carbon black production.

⛽ 3. Petroleum
Thick, dark liquid fossil fuel (C₁–C₄₀ hydrocarbons: alkanes, alkenes, cycloalkanes, aromatics + small inorganic compounds).
🔹 Separation: Fractional distillation → separates into fractions by boiling points (gasoline, kerosene, diesel, lubricants, etc.).

OR

What do you mean by diversity and magnitude of organic compounds? Give at least 5 reasons.

Answer

📘 Diversity & Magnitude of Organic Compounds
Over 10 million organic compounds exist — far more than all other elements combined. Carbon’s unique properties explain this vast diversity.

1️⃣ Tetravalency
Carbon bonds with four atoms at once, forming stable structures.

2️⃣ Catenation
Self-linking property → long chains/rings of C–C bonds. Stronger C–C bonds (355 kJ/mol) compared to Si–Si (200 kJ/mol).

3️⃣ Isomerism
Same molecular formula → different structures. Example: C₅H₁₂ (pentane) has 3 isomers.

4️⃣ Multiple Bond Formation
Carbon forms double/triple bonds: C=C, C≡C, C=O, C=S, C≡N. Adds variety of structures.

5️⃣ Strength of Covalent Bonds
Small size → strong covalent bonds with C, H, O, N, halogens → stability and diversity.

OR
Give classification of organic compounds and the important characteristic of organic compounds.

Answer

📘 Classification of Organic Compounds
Organic compounds are broadly divided into:
1️⃣ Open chain (acyclic) compounds
2️⃣ Closed chain (cyclic) compounds

🔹 1. Open Chain or Acyclic Compounds
Carbon atoms linked in open chains (straight or branched). Also called aliphatic compounds.
➡️ Examples: n-pentane, isopentane, n-butane, isobutane.
Types:
(i) Saturated (alkanes, C_nH_2n+2)
(ii) Unsaturated (alkenes C_nH_2n, alkynes C_nH_2n−2)

📊 Difference: Saturated vs Unsaturated Hydrocarbons
✅ Saturated: C–C single bonds, more H per C, less reactive, substitution reactions, stable, burn with blue flame.
✅ Unsaturated: C=C or C≡C bonds, fewer H per C, more reactive, addition reactions, less stable, burn with yellow sooty flame.

🔹 2. Closed Chain or Cyclic Compounds
Carbon atoms form rings.
➡️ Examples: cyclobutane, benzene, phenol.
Types:
(a) Homocyclic (only carbon atoms in ring)
(b) Heterocyclic (rings with O, N, S atoms)

🌀 Homocyclic Compounds
(i) Aromatic (benzene ring, alternating double bonds, e.g. benzene, naphthalene).
(ii) Alicyclic (non-benzenoid rings, e.g. cyclopentane).

🧪 Heterocyclic Compounds
Rings with carbon + other atoms (O, N, S). Example: pyridine, furan.

📗 General Characteristics of Organic Compounds
1️⃣ Presence of carbon + few elements (H, O, N, S, halogens).
2️⃣ Living origin (plants, animals, minerals).
3️⃣ Covalent nature (non-ionic).
4️⃣ Solubility: insoluble in water, soluble in organic solvents.
5️⃣ Non-conductors of electricity.
6️⃣ Low melting/boiling points, volatile.
7️⃣ Less stable than inorganic compounds.
8️⃣ Combustible, burn to form CO₂.
9️⃣ Slow reactivity, often low yield.

2️⃣5️⃣

What are Lipids? Write down the sources and uses of lipids. Write five differences between Fats and Oils.

Answer

📘 Definition
Lipids are naturally occurring heterogeneous organic compounds (C, H, O, sometimes P & N) including fats, oils, waxes. They are insoluble in water but soluble in organic solvents (ether, benzene, chloroform).

🌱 Sources of Lipids
🐟 Animals → Marine animals (salmon, whales), butter, ghee, cheese.
🌻 Plants → Sunflower, coconut, groundnut, corn, cotton seed, olive.

⚡ Uses of Lipids
1️⃣ Transport fatty acids & fat-soluble vitamins (A, D, E, K).
2️⃣ Some lipids reduce cholesterol.
3️⃣ Used in cooking & frying.
4️⃣ Used in detergents, soaps, cosmetics, polishes, paints.
5️⃣ Activate enzymes.
6️⃣ Stored in adipose tissue; milk gives butter & ghee for food & bakery.

📊 Differences between Fats and Oils
✅ Fats:
• Solid at room temperature.
• Usually from animals.
• Saturated compounds.
• High melting points.
• Increase cholesterol.

✅ Oils:
• Liquid at room temperature.
• Usually from plants.
• Unsaturated compounds.
• Low melting points.
• Maintain cholesterol.

OR
What are proteins and peptide bond? How peptide bond is formed in dipeptides and tripeptides? Write down the range of Number of Amino Acids & molecular weights of Proteins. Give importance & sources of proteins.

Answer

📘 Definition of Proteins
Proteins (Greek “Proteios” = first) are macromolecular nitrogenous compounds made of amino acids linked by peptide bonds. They are polymers of amino acids and yield amino acids upon hydrolysis.

📗 Definition of Peptide Bond
A peptide bond is an acid-amide linkage formed between amino acids by elimination of water. Thousands of amino acids linked form proteins.

🧪 Formation
• Two amino acids → dipeptide.
• Three amino acids → tripeptide.
• Many amino acids → polypeptide/protein.

🔢 Range of Amino Acids & Molecular Weights
• Number of amino acids in proteins: 60 – 6000.
• Molecular weight: 43,000 – 50,000,000 daltons (1 Da = 1 amu).
• Total amino acids: 20.
• Essential amino acids: 10.
• Non-essential amino acids: 10.

🌱 Sources & Importance of Proteins
1️⃣ Animal proteins → meat, poultry, fish, eggs (essential for protoplasm).
2️⃣ Enzymes → proteins catalyzing reactions; used in pharmaceuticals.
3️⃣ Hides → proteins used for leather (shoes, jackets, sports goods).
4️⃣ Bones → yield gelatin, used in bakery.
5️⃣ Plant proteins → pulses, beans, legumes, used as food.

2️⃣6️⃣

Describe in detail nucleic acids, RNA and DNA. Give five points to differentiate between DNA and RNA. Write down importance of deoxyribonucleic acid (DNA).

Answer

📘 Definition
Nucleic acids were discovered by Friedrich Miescher in 1869. They are biopolymers (long-chain macromolecules) formed by polymerization of nucleotides. Elements present: C, H, O, N, and P.

📗 DNA (Deoxyribonucleic Acid)
• Double-stranded helix.
• Sugar: deoxyribose.
• Bases: A, G, C, T.
• Found mainly in nucleus (also mitochondria).

📗 RNA (Ribonucleic Acid)
• Single-stranded molecule.
• Sugar: ribose.
• Bases: A, G, C, U.
• Found in nucleolus, cytoplasm, ribosomes.
• Types: mRNA, tRNA, rRNA.

📊 DNA vs RNA Comparison

Parameter	DNA	RNA
Pentose Sugar	Deoxyribose	Ribose
Bases	A, G, C, T	A, G, C, U
Strands	Double-stranded helix	Single-stranded
Size	Large polymers	Smaller, variable
Stability	Stable, long-lived	Unstable, short-lived
Location	Nucleus (also mitochondria)	Cytoplasm, ribosomes
Function	Stores genetic info	Protein synthesis regulation
Types	One kind	Three types (mRNA, tRNA, rRNA)

🌍 Importance of DNA
• Stores genetic information.
• Controls heredity and traits.
• Directs protein synthesis.
• Maintains cellular functions.
• Basis of biotechnology, genetic engineering, forensic science.

OR
What are vitamins. Differentiate its two types with their sources. Name the diseases caused by the deficiency of both types of vitamins.

Answer

📘 Definition
Vitamins are essential nutrients required in small amounts for normal growth and metabolism. Discovered by Hopkins (1912) and named by Funk.

📗 Types of Vitamins
1️⃣ Water-Soluble → B-complex (10 vitamins), Vitamin C.
2️⃣ Fat-Soluble → Vitamins A, D, E, K.

📊 Vitamins Comparison

Vitamin	Sources	Importance	Deficiency Diseases
A	Butter, fish, eggs, milk, cheese, carrots, liver	Eyes (visual pigments), skin	Night blindness, xerophthalmia, dry skin
B-complex	Wheat, rice, eggs, milk, meat, liver, nuts, yeast	Nerves, skin	Beri beri, dermatitis, hair loss, tongue/lip inflammation
C (Ascorbic acid)	Oranges, lemon, tomatoes, green peppers	Wound healing, prevent bleeding & cold	Scurvy (swollen gums, reopened wounds)
D	Fish liver, dairy, mushrooms, sunlight	Bones, teeth (Ca & P metabolism)	Rickets (soft, weak bones in children)
E	Plant oils, leafy vegetables	Cell membrane, reproduction	Sterility, haemolysis (fragile RBCs)
K	Green vegetables (spinach, cabbage), cereals	Blood clotting factor	Haemorrhage (delayed clotting)

2️⃣7️⃣

What is saponification? Describe the raw materials used in the preparation of soap. Describe process of Saponification with the help of flow sheet diagram.

Answer

📘 Saponification
The chemical process for the preparation of soap is called saponification. It is the reaction of triglycerides (fats/oils) with sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form glycerol and fatty acid salts (soap).

⚡ Role of Alkali
• NaOH → Produces hard soap.
• KOH → Produces soft soap (more soluble, used in shaving creams & textile industry).

🧪 Raw Materials
1️⃣ Oils & fats (triglycerides).
2️⃣ Alkali (NaOH or KOH).
3️⃣ Water (solvent).
4️⃣ Additives (fragrance, color, antiseptics).

📊 Flow Sheet Diagram (Process)
Oils/Fats ➡️ Alkali (NaOH/KOH) ➡️ Heating ➡️ Saponification Reaction ➡️ Soap + Glycerol ➡️ Cooling & Solidification ➡️ Cutting into bars.

OR
Define Atmosphere. Enlist the layers of atmosphere. Differentiate between troposphere and stratosphere.

Answer

📘 Definition of Atmosphere
The atmosphere is a layer of gases surrounding the Earth, held by gravity. It is essential for life, weather, and climate.

📗 Layers of Atmosphere
1️⃣ Troposphere
2️⃣ Stratosphere
3️⃣ Mesosphere
4️⃣ Thermosphere
5️⃣ Exosphere

📊 Troposphere vs Stratosphere

Parameter	Troposphere	Stratosphere
Altitude	0 – 12 km	12 – 50 km
Temperature	Decreases with height	Increases with height (due to ozone)
Weather	Contains clouds, rain, storms	No weather phenomena
Composition	Mainly N₂, O₂, CO₂, water vapor	Contains ozone layer
Importance	Supports life & weather	Protects from harmful UV rays

2️⃣8️⃣

Justify that electrochemical methods depend upon electrochemical cells.

Answer

📘 Electrochemical Methods
Electrochemical methods are analytical techniques that measure potential, charge, or electrical properties of a solution. These methods rely on **electrochemical cells** to provide voltage and current for reactions.

⚡ Electrochemical Cell
• Consists of two half-cells: anode (e.g. Zn) and cathode (e.g. Cu).
• Electrodes are dipped in electrolytic solutions (ZnSO₄ at anode, CuSO₄ at cathode).
• Connected by a salt bridge (NaCl) for ionic connectivity.
• Anode → oxidation (negative electrode).
• Cathode → reduction (positive electrode).

🧪 Working Principle
• Voltage source drives ion movement.
• Chemical reactions at electrodes generate current.
• Current depends on concentration of electroactive species.
• Thus, electrochemical cells are the foundation of electrochemical methods.

OR
What is Titrimetric Analysis? Describe how it is performed with diagram.

Answer

📘 Definition
Titrimetric analysis (volumetric analysis) determines the concentration of a substance by reacting it with a solution of known concentration (titrant).

📗 Key Terms
• 🔹 Titration → Comparison of volumes of known vs unknown solutions.
• 🔹 Titrant → Solution of known concentration (e.g. NaOH, HCl).
• 🔹 Analyte → Substance being analyzed (e.g. NaCl, gold).
• 🔹 Indicator → Shows end point by color change (litmus, phenolphthalein, methyl orange).

🧪 General Reaction
aA + tT → Product
(a = moles of analyte, t = moles of titrant).

📊 Process (Flow Diagram)
1️⃣ Burette → contains titrant (known solution).
2️⃣ Flask → contains analyte (unknown solution).
3️⃣ Add indicator to flask.
4️⃣ Titrant added dropwise until end point (color change).
5️⃣ Volume of titrant used → concentration of analyte calculated.

🔎 Diagram (Text Form)
Burette (titrant) ➡️ Flask (analyte + indicator) ➡️ Dropwise addition ➡️ Neutralization ➡️ End point (color change) ➡️ Calculation of concentration.

2️⃣9️⃣

Explain the process of preparation of sugar from sugarcane.

Answer

📘 Preparation of Sugar from Sugarcane
The process of sugar production from sugarcane involves six main steps:

1️⃣ Extraction of Juice
Sugarcane is crushed in mills to extract juice.

2️⃣ Clarification
Juice is heated and treated with lime to remove impurities and neutralize acids.

3️⃣ Concentration
The clarified juice is evaporated in multiple-effect evaporators to form thick syrup.

4️⃣ Crystallization
Syrup is further boiled in vacuum pans to form sugar crystals.

5️⃣ Separation
Crystals are separated from molasses using centrifuges.

6️⃣ Drying & Packaging
Sugar crystals are dried, graded, and packed for use.

📊 Flow Sheet (Text Form)
Sugarcane → Crushing → Juice Extraction → Clarification → Concentration → Crystallization → Separation → Drying → Packaging.

3️⃣0️⃣

What is Ozone? How does Ozone depletion occur by Chlorofluorocarbons (CFCs) also mention some adverse impact of it?

Answer

📘 Ozone
Ozone (O₃) is a triatomic molecule of oxygen present in the stratosphere. It forms the **ozone layer**, which absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth.

⚡ Ozone Depletion by CFCs
• Chlorofluorocarbons (CFCs) released from refrigerators, air conditioners, and aerosols rise to the stratosphere.
• UV radiation breaks down CFCs, releasing chlorine atoms.
• Chlorine reacts with ozone (O₃), breaking it into oxygen (O₂) and reducing ozone concentration.
• One chlorine atom can destroy thousands of ozone molecules.

🌍 Adverse Impacts of Ozone Depletion
1️⃣ Increased UV radiation reaching Earth.
2️⃣ Skin cancer and eye diseases (cataracts).
3️⃣ Reduced crop yield and damage to plants.
4️⃣ Harmful effects on aquatic life (phytoplankton).
5️⃣ Weakening of immune system in humans.

OR
Describe global warming. Justify that greenhouse effect leads to global warming.

Answer

📘 Definition of Global Warming
Global warming is the gradual rise in Earth’s average surface temperature due to increased greenhouse gases, especially CO₂.

⚡ Reason
Earth’s average temperature (~15°C) is rising due to long-term climate change caused by greenhouse gases trapping heat.

🌍 Greenhouse Effect
• CO₂ and other gases absorb infrared radiation from Earth’s surface.
• Prevents heat escape, keeping Earth warm at night.
• Higher CO₂ → stronger greenhouse effect → global warming.

🔹 Greenhouse Gases
CO₂, CH₄, N₂O, water vapors, ozone.

📊 Effects of Global Warming
1️⃣ Rising atmospheric temperature (~0.05°C annually).
2️⃣ More frequent extreme weather (floods, cyclones).
3️⃣ Melting glaciers → rising sea levels → flooding of low-lying areas.
4️⃣ Acid rain, irregular crop patterns.
5️⃣ Lifestyle changes and ecological imbalance.

✅ Prevention
Reduce greenhouse gas emissions, use renewable energy, improve energy efficiency, adopt sustainable practices in transport & agriculture.

3️⃣1️⃣

Describe Gas Chromatography with diagram also write two uses of gas chromatography.

Answer

📘 Definition
Gas Chromatography (GC) or Gas-Liquid Chromatography is a technique used for separation, identification, and quantification of volatile organic compounds. It works on the principle of **partition chromatography** between a mobile phase (gas) and a stationary phase (liquid/solid inside a column).

⚡ Purpose
• Separation of compounds with high volatility.
• Suitable for low molecular weight and thermally stable compounds.

🔹 Phases
• Mobile Phase → Inert carrier gas (e.g. helium, nitrogen).
• Stationary Phase → Viscous liquid coated on solid support (e.g. silica) packed in a long capillary column.

🧪 Principle
• Sample injected → carried by mobile phase gas → passes through stationary phase column.
• Components separate based on affinity to stationary vs mobile phase.
• Detector records retention time → chromatogram produced.

📊 Diagram (Text Form)
Sample Injector ➡️ Carrier Gas ➡️ Column (stationary phase) ➡️ Detector ➡️ Chromatogram (graph of peaks).

🌍 Uses of Gas Chromatography
1️⃣ Separation of volatile mixtures (e.g. hydrocarbons in petroleum).
2️⃣ Qualitative & quantitative analysis of food, drugs, pollutants.

✅ Advantages
• Fast analysis.
• High sensitivity.
• Good separation efficiency.
• Requires small sample.

OR
Describe HPLC in detail.

Answer

📘 Definition
HPLC (High Performance Liquid Chromatography) is a technique for rapid separation of compounds using high-pressure pumps to pass liquid mobile phase through a column packed with absorbent material.

⚡ Instrument Components
• Reservoir (mobile phase).
• Pump (ensures high pressure flow).
• Injector (introduces sample).
• Column (stationary phase for separation).
• Detector (records elution).
• Computer (data acquisition).

🧪 Working
• Sample injected → mobile phase pumped through column → components separated based on affinity.
• Detector senses elution → chromatogram produced.

🌍 Applications
• Drug discovery & pharmaceutical analysis.
• Clinical & cosmetic analysis.
• Environmental chemistry (pollutants).
• Biochemical genetics.

OR
What is spectroscopy? How is it used in the chemical analysis of a substance? Also discuss its types.

Answer

📘 Definition
Spectroscopy is the study of the interaction of light (electromagnetic radiation) with matter as a function of wavelength or frequency. It is widely used in chemistry for identification of substances through their **emission or absorption spectra**.

⚡ Usage in Chemical Analysis
• Determines concentration of atomic, molecular, or ionic species.
• Instruments: spectrometer, spectrophotometer, spectrograph.
• Provides both qualitative (identity) and quantitative (amount) information.

📗 Types of Spectroscopy

🔹 1. Ultraviolet & Visible Spectroscopy (Electronic Spectroscopy)
• Measures absorption of UV/visible light by compounds.
• Principle: interaction of UV light with electrons → absorption spectrum.
• Wavelength range: 192 – 900 nm.

🔹 2. Infrared Spectroscopy (Vibrational Spectroscopy)
• Introduced in 1950, cost-effective and non-hazardous.
• Identifies functional groups in organic molecules, food, polymers, industrial products.
• Wavelength range: 2.5 – 15 μm (wave number 4000 – 625 cm⁻¹).
• Principle: IR radiation absorbed → molecular vibrations; transmitted energy recorded.

✅ Conclusion
Spectroscopy is a powerful analytical tool that helps in **identifying, quantifying, and characterizing** chemical substances by studying how they interact with light.

3️⃣2️⃣

Differentiate between Soft Water and Hard Water and describe different methods of removing temporary and permanent hardness. Write down 5 disadvantages of hard water.

Answer

📘 Soft Water
• Contains very small amounts of Ca²⁺ and Mg²⁺ salts.
• Produces lather easily with soap, no curdy precipitate.

📘 Hard Water
• Contains larger amounts of Ca²⁺ and Mg²⁺ salts (bicarbonates, chlorides, sulphates).
• Does not produce lather with soap, forms curdy precipitate.

📊 Soft Water vs Hard Water

Property	Soft Water	Hard Water
Ca²⁺ & Mg²⁺ salts	Small quantity	Large quantity
Soap action	Forms lather easily	Forms curdy precipitate
Cleaning	Effective	Ineffective

⚡ Methods of Removing Hardness

🔹 1. Temporary Hardness by Boiling
Ca(HCO₃)₂(aq) → CaCO₃(s) ↓ + H₂O + CO₂
Mg(HCO₃)₂(aq) → MgCO₃(s) ↓ + H₂O + CO₂

🔹 2. Temporary Hardness by Clark’s Method (Lime Process)
Ca(HCO₃)₂(aq) + Ca(OH)₂(aq) → 2CaCO₃(s) ↓ + 2H₂O(l)
Mg(HCO₃)₂(aq) + Ca(OH)₂(aq) → CaCO₃(s) ↓ + MgCO₃(s) ↓ + 2H₂O(l)

🔹 3. Permanent Hardness by Washing Soda
CaSO₄(aq) + Na₂CO₃(aq) → CaCO₃(s) ↓ + Na₂SO₄(aq)
MgCl₂(aq) + Na₂CO₃(aq) → MgCO₃(s) ↓ + 2NaCl(aq)
MgSO₄(aq) + Na₂CO₃(aq) → MgCO₃(s) ↓ + Na₂SO₄(aq)

🌍 Disadvantages of Hard Water
1️⃣ Hampers washing → consumes more soap, no lather.
2️⃣ Leaves stains on clothes, tiles, utensils.
3️⃣ Causes dry, rough hair and possible hair loss.
4️⃣ Leads to dry, itchy skin (eczema-like symptoms).
5️⃣ Corrodes and clogs pipes due to scale deposits.

3️⃣3️⃣

Definition of Water Pollution. Write down its Causes and Effects on Life.

Answer

📘 Definition
Water pollution is the contamination of lakes, rivers, oceans, and groundwater with harmful substances, making water unfit for drinking and unsafe for living organisms.

⚡ Causes
• Dumping of untreated industrial and domestic waste.
• High solubility of water dissolves many pollutants easily.

🌍 Effects on Life
1️⃣ Causes diseases like cholera, typhoid, diarrhea.
2️⃣ Harmful to animals and birds.
3️⃣ Promotes algal bloom → reduces oxygen → harms aquatic life.
4️⃣ Degrades beauty of lakes and rivers.
5️⃣ Unfit for washing and cleaning.

OR
Define pollutant. Enlist the names of seven types of pollutants. What are primary and secondary air pollutants? Give the sources, environmental and health risks of the following: COₓ, SOₓ, NOₓ, lead, ozone.

Answer

📘 Definition of Pollutant
A pollutant is any substance (solid, liquid, or gas) that contaminates the environment (air, water, soil) and makes it toxic or harmful to life.

📗 Seven Types of Pollutants
1️⃣ Carbon oxides (CO, CO₂)
2️⃣ Sulphur oxides (SO₂, SO₃)
3️⃣ Nitrogen oxides (NO, NO₂)
4️⃣ Ozone (O₃)
5️⃣ Particulate matter (dust, smoke)
6️⃣ Heavy metals (lead, mercury)
7️⃣ Hydrocarbons (volatile organic compounds)

⚡ Primary vs Secondary Air Pollutants
• Primary → Directly emitted into atmosphere (CO, SO₂, NO, Pb).
• Secondary → Formed by chemical reactions of primary pollutants (ozone, smog, acid rain).

📊 Major Pollutants: Sources, Environmental & Health Risks

🔹 Carbon monoxide (CO)
• Source: Incomplete combustion of fuels.
• Environmental Risk: Contributes to smog.
• Health Risk: Chest discomfort, visual problems, reduced physical/mental ability.

🔹 Nitrogen oxides (NOₓ)
• Source: Vehicle exhausts, power plants.
• Environmental Risk: Promote pollution, damage plants.
• Health Risk: Respiratory irritation, inflammation.

🔹 Sulphur dioxide (SO₂)
• Source: Burning coal, oil, industrial emissions.
• Environmental Risk: Causes acid rain, damages flora & monuments.
• Health Risk: Breathing problems, harmful for asthma patients.

🔹 Ozone (O₃)
• Source: Secondary pollutant formed by NOₓ + VOCs under sunlight.
• Environmental Risk: Damages plants, reduces crop yield.
• Health Risk: Lung impairment, breathing irritation.

🔹 Particulate Matter (PM)
• Source: Dust, smoke, industrial emissions.
• Environmental Risk: Creates haze, acid rain, harms vegetation.
• Health Risk: Asthma, irregular heartbeat, respiratory discomfort.

🔹 Lead (Pb)
• Source: Industrial waste, old paints, batteries.
• Environmental Risk: Biodiversity loss, neurological issues in animals.
• Health Risk: Learning problems in children, cardiovascular issues in adults.

💥 جونؔ ایلیا 🎯 💥

💭 بے دلی کیا یوں ہی دن گزر جائیں گے
💔 صرف زندہ رہے ہم تو مر جائیں گے

🎶 رقص ہے رنگ پر رنگ ہم رقص ہیں
🌌 سب بچھڑ جائیں گے سب بکھر جائیں گے

🍷 یہ خراباتیان خرد باختہ
🌅 صبح ہوتے ہی سب کام پر جائیں گے

💕 کتنی دل کش ہو تم کتنا دلجو ہوں میں
⚡ کیا ستم ہے کہ ہم لوگ مر جائیں گے

🌟 ہے غنیمت کہ اسرار ہستی سے ہم
🕊️ بے خبر آئے ہیں بے خبر جائیں گے

🔥 جونؔ ایلیا ۔ غزل 🔥

🌸 ہے بکھرنے کو یہ محفلِ رنگ و بُو، تم کہاں جاؤ گے ہم کہاں جائیں گے
🕊️ ہر طرف ہو رہی ہے یہی گفتگو، تم کہاں جاؤ گے ہم کہاں جائیں گے

💭 کوئی حاصل نہ تھا آرزو کا مگر، سانحہ یہ ہے اب آرزو بھی نہیں
⏳ وقت کی اس مسافت میں بے آرزو، تم کہاں جاؤ گے ہم کہاں جائیں گے

🔥 ایک جنوں تھا کہ آباد ہو شہرِ جاں، اور آباد جب شہرِ جاں ہو گیا
🌌 ہیں یہ سرگوشیاں دربدر کوبکو، تم کہاں جاؤ گے ہم کہاں جائیں گے

🛤️ کس قدر دور سے لوٹ کر آئے ہیں، یوں کہوں عمر برباد کر آئے ہیں
💔 تھا سراب اپنا سرمایۂِ جستجو، تم کہاں جاؤ گے ہم کہاں جائیں گے

🌿 دشت میں رقصِ شوقِ بہار اب کہاں، بعدِ پیمائ دیوانہ وار اب کہاں
🌙 بس گزرنے کو ہے موسمِ ہائے و ہُو، تم کہاں جاؤ گے ہم کہاں جائیں گے

🎶 ہر متاعِ نفس نذرِ آہنگ کی، ہم کو یاراں ہَوس تھی بہت رنگ کی
🌹 گُل زمیں سے ابلنے کو ہے اب لہو، تم کہاں جاؤ گے ہم کہاں جائیں گے؟

🌙 اولِ شب کا مہتاب بھی جا چکا، صحنِ مے خانہ سے اب افق میں کہیں
🍷 آخرِ شب ہے خالی ہیں جام و سُبو، تم کہاں جاؤ گے ہم کہاں جائیں گے؟

🌸 دشت میں رقصِ شوقِ بہار اب کہاں، بادہ پیمائی دیوانہ دار اب کہاں
🔥 بس گزرنے کو ہے موسمِ ہاؤ و ہُو، تم کہاں جاؤ گے ہم کہاں جائیں گے؟

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

🌸 کتنے عیش سے رہتے ہوں گے کتنے اتراتے ہوں گے
💭 جانے کیسے لوگ وہ ہوں گے جو اس کو بھاتے ہوں گے

🌙 شام ہوئے خوش باش یہاں کے میرے پاس آ جاتے ہیں
🔥 میرے بجھنے کا نظارہ کرنے آ جاتے ہوں گے

🚶 وہ جو نہ آنے والا ہے نا اس سے مجھ کو مطلب تھا
💔 آنے والوں سے کیا مطلب آتے ہیں آتے ہوں گے

🍃 اس کی یاد کی باد صبا میں اور تو کیا ہوتا ہوگا
🌌 یوں ہی میرے بال ہیں بکھرے اور بکھر جاتے ہوں گے

🤝 یارو کچھ تو ذکر کرو تم اس کی قیامت بانہوں کا
💔 وہ جو سمٹتے ہوں گے ان میں وہ تو مر جاتے ہوں گے

🕊️ میرا سانس اکھڑتے ہی سب بین کریں گے روئیں گے
🌙 یعنی میرے بعد بھی یعنی سانس لیے جاتے ہوں گے

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

🌙 زندانیانِ شام و سحر خیریت سے ہیں
💭 ہر لمحہ جی رہے ہیں مگر خیریت سے ہیں

🏙️ شہرِ یقیں میں اب کوئی دم خم نہیں رہا
🌌 دشتِ گماں کے خاک بسر خیریت سے ہیں

🙏 آخر ہے کون جو کسی پل کہ سکے یہ بات
🕊️ اللہ اور تمام بشر خیریت سے ہیں

💡 ہے اپنے اپنے طور پہ ہر چیز اس گھڑی
💧 مژگانِ خشک و دامنِ تر خیریت سے ہیں

👀 اب فیصلوں کا کم نظروں پر مدار ہے
🌟 یعنی تمام اہلِ نظر خیریت سے ہیں

🦶 پیروں سے آبلوں کا وہی ہے معاملہ
🔥 سودائیانِ حال کے سر خیریت سے ہیں

🏚️ ہم جن گھروں کو چھوڑ کے آئے تھے ناگہاں
💭 شکوے کی بات ہے، وہ اگر خیریت سے ہیں

🌬️ لو چل رہی ہے، محو ہے اپنے میں دوپہر
🏚️ خاک اڑ رہی ہے اور کھنڈر خیریت سے ہیں

👥 ہم اہلِ شہر اپنے جوانوں کے درمیاں
✨ جونؔ! ایک معجزہ ہے اگر خیریت سے ہیں

🎨 برباد ہوچکا ہے ہنر اک ہنر کے ساتھ
📜 اور اپنے صاحبانِ ہنر خیریت سے ہیں

🕊️ شکرِ خدا شہید ہوئے اہلِ حق تمام
⚔️ برگستوان و تیغ و تبر خیریت سے ہیں

🏰 اب اس کا قصرِ ناز کہاں اور وہ کہاں
🚪 بس در ہے اور بندئہ در خیریت سے ہیں

✍️ ہم ہیں کہ شاعری ہے ہمارے لئے عذاب
📖 ورنہ تمام جوشؔ و جگرؔ خیریت سے ہیں

📚 شاعر تو دو ہیں میرؔ تقی اور میر جونؔ
🌙 باقی جو ہیں وہ شام و سحر خیریت سے ہیں

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

🌅 ایک ہی مژدہ صبح لاتی ہے
☀️ دھوپ آنگن میں پھیل جاتی ہے

🍃 رنگ موسم ہے اور بادِ صبا
🌆 شہر کوچوں میں خاک اڑاتی ہے

📄 فرش پر کاغذ اڑتے پھرتے ہیں
🕰️ میز پر گرد جمتی جاتی ہے

💭 سوچتا ہوں کہ اس کی یاد آخر
🌙 اب کسے رات بھر جگاتی ہے

🎶 میں بھی اذنِ نواگری چاہوں
💔 بے دلی بھی تو لب ہلاتی ہے

🌳 سوگئے پیڑ جاگ اٹھی خوشبو
🌸 زندگی خواب کیوں دکھاتی ہے

💔 اس سراپا وفا کی فرقت میں
💭 خواہشِ غیر کیوں ستاتی ہے

🤝 آپ اپنے سے ہم سخن رہنا
😮 ہمنشیں! سانس پھول جاتی ہے

😔 کیا ستم ہے کہ اب تِری صورت
👀 غور کرنے پہ یاد آتی ہے

🏚️ کون اس گھر کی دیکھ بھال کرے
💔 روز ایک چیز ٹوٹ جاتی ہے

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

🌟 یہ ملکِ جاں یہ حقیقت نہ رائیگاں جائے
💭 یہ دل کے خواب کی صورت نہ رائیگاں جائے

🏙️ ہے شہر شہر کی محنت یہ منزلِ مقصود
🌌 یہ شہر شہر کی محنت نہ رائیگاں جائے

🤝 یہ رنگ رنگ کے رشتے بکھر نہ جائیں کہیں
💡 یہ خود سے اپنی رفاقت نہ رائیگاں جائے

🌸 سوائے حسنِ طبیعت دھرا بھی اب کیا ہے
🌙 کہیں یہ حسنِ طبیعت نہ رائیگاں جائے

🔊 ہے گوشہ گوشہ یہاں سازشوں کی سرگوشی
💔 ہمارا عہدِ محبت نہ رائیگاں جائے

👥 کہاں کہاں سے یہاں آکے ہم ہوئے ہیں بہم
✨ یہ اجتماع یہ صحبت نہ رائیگاں جائے

⏳ نہ بھولنا کہ یہ مہلت ہے آخری مہلت
🌟 رہے خیال یہ مہلت نہ رائیگاں جائے

💭 مجھے تو اے میرے دل تجھ سے ہے یہی کہنا
🔥 تیرے جنون کی حالت نہ رائیگاں جائے

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

🌙 نشئہ ماہ و سال ہے، تاحال
💭 شوق اس کا کمال ہے، تاحال

🌸 نکہتِ گل ادھر نہ آئیو تو
😔 جی ہمارا نڈھال ہے، تاحال

💔 میرا سینہ چھلا ہوا ہے مگر
⚡ شوقِ بحث و جدال ہے، تاحال

🌀 اس عبث خانئہ حوادث میں
❓ ہر جواب اک سوال ہے، تاحال

⏳ بڑھ رہا ہوں زوال کی جانب
💔 دل میں زخمِ کمال ہے، تاحال

🏚️ کب کا تاراج ہوچکا ہوں مگر
🌟 ذہن میں اک مثال ہے، تاحال

💔 زخمِ کاری کے باوجود
🌿 ہوسِ اندمال ہے، تاحال

🧣 دامنِ آلودگی کے بعد بھی تو
🌸 آپ اپنی مثال ہے، تاحال

💭 ہے یہ صورت کہ اشتیاق اس کا
💔 بے امیدِ وصال ہے، تاحال

😔 تھا جو شکوہ سو ہے وہ تاایں دم
🌙 وہ جو تھا اک ملال ہے، تاحال

💔 زندگی ہے لہولہان مگر
🎨 رنگ بے خدوخال ہے، تاحال

📖 ہے سوادِ ختن غزل میری
🦌 تو غزل کا غزال ہے، تاحال

🌹 لالہ رویا، شکن شکن مویا
💭 تجھ کو پانا محال ہے، تاحال

🩺 کتنے چارہ گروں نے زحمت کی
😔 پر وہی میرا حال ہے، تاحال

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

💭 نہیں جذبے کسی بھی قیمت کے
🌙 ہم ہیں حیران اپنی حیرت کے

🤔 اس میں آخر عجب کی بات ہے کیا
💔 تم نہیں تھے مری طبیعت کے

😔 پوچھ مت بے شکایتی کا عذاب
🌟 کیا عجب عیش تھے شکایت کے

💧 یہ جو آنسو ہیں، رخصتی آنسو
🎁 یہ عطیے ہیں دل کی عادت کے

📜 ہم ہی شیعوں کے مجتہد ہیں مغاں!
⚖️ ہم ہی مفتی ہیں اہلسنت کے

💉 ہم تو بس خون تھوکتے ہیں میاں
🛠️ نہیں خوگر کسی مشقت کے

💕 یہ جو لمحے ہیں وصال کے ہیں میاں
🌙 ہیں یہ لمحے تمام ہجرت کے

✨ جونؔ، یزدان و آدم و ابلیس
📖 ہیں عجب معجزے حکایت کے

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

❤️ دل نے وفا کے نام پر کارِ وفا نہیں کیا
💔 خود کو ہلاک کر لیا، خود کو فدا نہیں کیا

🤔 کیسے کہیں کہ تجھ کو بھی ہم سے ہے واسطہ کوئی
😔 تو نے تو ہم سے آج تک کوئی گلہ نہیں کیا

⚖️ تو بھی کسی کے باب میں عہد شکن ہو غالباً
📜 میں نے بھی ایک شخص کا قرض ادا نہیں کیا

🗣️ جو بھی ہو تم پہ معترض، اُس کو یہی جواب دو
🌟 آپ بہت شریف ہیں، آپ نے کیا نہیں کیا

👑 جس کو بھی شیخ و شاہ نے حکمِ خُدا دیا قرار
🙏 ہم نے نہیں کیا وہ کام، ہاں باخُدا نہیں کیا

📖 نسبتِ علم ہے بہت حاکمِ وقت کو عزیز
💡 اُس نے تو کارِ جہل بھی بے علما نہیں کیا

✍️ جونؔ ایلیا

💥 غزل ۔۔۔۔ جونؔ ایلیا 💥

📖 حال خوش تذکرہ نگاروں کا
🌙 تھا تو اک شہر خاکساروں کا

💔 پہلے رہتے تھے کوچۂ دل میں
😔 اب پتہ کیا ہے دل فگاروں کا

🚪 کوئے جاناں کی ناکہ بندی ہے
🛏️ بسترا اب کہاں ہے یاروں کا

🌬️ چلتا جاتا ہے سانس کا لشکر
🕊️ کون پُرساں ہے یادگاروں کا

💭 اپنے اندر گھسٹ رہا ہوں میں
🌌 مجھ سے کیا ذکر رہ گزاروں کا

🎉 ان سے جو شہر میں ہیں بے دعویٰ
🌟 عیش مت پوچھ دعویداروں کا

⚔️ کیسا یہ معرکہ ہے برپا جو
🐎 نہ پیادوں کا نہ سواروں کا

🖋️ بات تشبیہہ کی نہ کیجیو تُو
📚 دہر ہے صرف استعاروں کا

💔 میں تو خیر اپنی جان ہی سے گیا
🤝 کیا ہوا جانے جانثاروں کا

🔥 کچھ نہیں اب سوائے خاکستر
🌪️ ایک جلسہ تھا شعلہ خواروں کا

✍️ جونؔ ایلیا

💥 حضرتِ جونؔ ایلیا 💥 🎨 خاتم الشعرا و شاعرِ بے مثل و بے بدل 🎨

👥 اپنے سب یار کام کررہے ہیں
🌙 اور ہم ہیں کہ نام کر رہے ہیں

🏛️ آنے والی اپر کلاس کی ہے
✨ ہم جو یہ اہمتمام کررہے ہیں

⚔️ تیغ بازی کا شوق اپنی جگہ
🔥 آپ تو قتلِ عام کررہے ہیں

🎶 داد و تحسین کا یہ شور ہے کیوں
💭 ہم تو خود سے کلام کررہے ہیں

😔 ہے وہ بے چارگی کا حال کہ ہم
🤝 ہر کسی کو سلام کررہے ہیں

🕊️ ہم تو بس یاد کے ہیں لوگ میاں
💔 اپنا ہونا حرام کررہے ہیں

👑 اک قتالہ چاہئے ہم کو
📢 ہم یہ اعلانِ عام کررہے ہیں

🍷 کیا بھلا ساغرِ سفال کہ ہم
🥂 ناف پیالے کو جام کررہے ہیں

📝 ہم تو آئے تھے عرضِ مطلب کو
🙏 اور وہ احترام کررہے ہیں

💨 نہ اٹھے آہ کا دھواں بھی کہ وہ
🌌 کوئے دل میں خرام کررہے ہیں

💋 اس کے ہونٹوں پہ رکھ کے ہونٹ اپنے
🕊️ بات ہی ہم تمام کررہے ہیں

🎉 ہم عجب ہیں کہ اس کے کوچے میں
🥁 بے سبب دھوم دھام کررہے ہیں

⚔️ کرکے بے پوشش اس صنم کو ہم
🗡️ تیغ کو بے نیام کررہے ہیں

🎭 کوئی بھی فن ہمیں نہیں آتا
⏳ دم کو بس دوام کررہے ہیں

🌟 ہم جو ہر لمحہ جی رہے ہیں جونؔ
🏛️ ہم ابد میں قیام کررہے ہیں

✍️ حضرتِ جونؔ ایلیا

💥 حضرتِ جونؔ ایلیا 💥 🎨 خاتم الشعرا و شاعرِ بے مثل و بے بدل 🎨

🤝 نیا اک رشتہ پیدا کیوں کریں ہم
💔 بچھڑنا ہے تو جھگڑا کیوں کریں ہم

🌙 خموشی سے ادا ہو رسمِ دوری
🔥 کوئی ہنگامہ برپا کیوں کریں ہم

📖 سنا دیں عصمتِ مریم کا قصّہ؟
❌ پر اب اس باب کو وا کیوں کریں ہم

💭 زلیخاے عزیزاں بات یہ ہے
⚖️ بھلا گھاٹے کا سودا کیوں کریں ہم

💕 ہماری ہی تمنّا کیوں کرو تم
🌟 تمہاری ہی تمنّا کیوں کریں ہم

🕰️ کیا تھا عہد جب لمحوں میں ہم نے
📜 تو ساری عمر ایفا کیوں کریں ہم

🗑️ اٹھا کر کیوں نہ پھینکیں ساری چیزیں
🚶 فقط کمروں میں ٹہلا کیوں کریں ہم

👥 جو اک نسل فرومایہ کو پہنچے
💡 وہ سرمایہ اکٹھا کیوں کریں ہم

🌍 نہیں دنیا کو جب پروا ہماری
😔 تو پھر دنیا کی پروا کیوں کریں ہم

🏙️ برہنہ ہیں سرِ بازار تو کیا
👀 بھلا اندھوں سے پردہ کیوں کریں ہم

🏠 ہیں باشندے اسی بستی کے ہم بھی
🤝 سو خود پر بھی بھروسا کیوں کریں ہم

💀 چبالیں کیوں نہ خود ہی اپنا ڈھانچا
🍽️ تمہیں راتب مہیا کیوں کریں ہم

⚰️ پڑی رہنے دو انسانوں کی لاشیں
🌪️ زمیں کا بوجھ ہلکا کیوں کریں ہم

🕌 یہ بستی ہے مسلمانوں کی بستی
🕊️ یہاں کارِ مسیحا کیوں کریں ہم

✍️ حضرتِ جونؔ ایلیا

🌸🔥 جون ایلیا دل کو چھو لینے والی غزل🔥🌸

💫 حال یہ ہے کہ خواہش پرسش حال بھی نہیں
💫 اس کا خیال بھی نہیں اپنا خیال بھی نہیں

🌿 اے شجر حیات شوق ایسی خزاں رسیدگی
🌿 پوشش برگ و گل تو کیا جسم پہ چھال بھی نہیں

📖 مجھ میں وہ شخص ہو چکا جس کا کوئی حساب تھا
📖 سود ہے کیا زیاں ہے کیا اس کا سوال بھی نہیں

🎶 مست ہیں اپنے حال میں دل زدگان و دلبراں
🎶 صلح و سلام تو کجا بحث و جدال بھی نہیں

🌟 تو مرا حوصلہ تو دیکھ داد تو دے کہ اب مجھے
🌟 شوق کمال بھی نہیں خوف زوال بھی نہیں

🌌 خیمہ گاہ نگاہ کو لوٹ لیا گیا ہے کیا
🌌 آج افق کے دوش پر گرد کی شال بھی نہیں

🍃 اف یہ فضائے احتیاط تا کہیں اڑ نہ جائیں ہم
🍃 باد جنوب بھی نہیں باد شمال بھی نہیں

💔 وجہ معاش بے دلاں یاس ہے اب مگر کہاں
💔 اس کے ورود کا گماں فرض محال بھی نہیں

⏳ غارت روز و شب تو دیکھ وقت کا یہ غضب تو دیکھ
⏳ کل تو نڈھال بھی تھا میں آج نڈھال بھی نہیں

🌙 میرے زمان و ذات کا ہے یہ معاملہ کہ اب
🌙 صبح فراق بھی نہیں شام وصال بھی نہیں

🌹 پہلے ہمارے ذہن میں حسن کی اک مثال تھی
🌹 اب تو ہمارے ذہن میں کوئی مثال بھی نہیں

🔥 میں بھی بہت عجیب ہوں اتنا عجیب ہوں کہ بس
🔥 خود کو تباہ کر لیا اور ملال بھی نہیں

💥 جونؔ ایلیا 🎯 💥

😊 گاہے گاہے بس اب یہی ہو کیا
❤️ تم سے مل کر بہت خوشی ہو کیا

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Get the X-Chemistry National Comprehensive Targeted Guess Paper 2026 for Class 10 Chemistry. Designed specially for Karachi Board students, this paper includes important MCQs, short questions, and long questions expected in the final exams 2026. Prepare smartly and score high with updated Karachi Board notes and exam tips!

X-Chemistry Karachi Board National Comprehensive Targeted Guess Paper 2026 with Complete Solution

🎯 X-Chemistry Karachi Board National Comprehensive Targeted Guess Paper 2026 with Complete Solution | Class 10 Chemistry Guess Paper

Total marks: 60

Time: 3 Hours

General Instructions

Section – A; contains 12 MCQs and all of them are to be answered.

Section – B; consists of 12 short-answer questions of which 8 are to be answered (24 marks)

Section – C; consists of 6 Long-answer questions of which 4 are to be answered (24marks)

🔥📘 Section-A ……….. MCQs (Compulsory question)

(12 marks) Model Set I

1️⃣. For the reaction 2A(g) + B(g) ⇌ 3C(g), the equilibrium constant expression is:

🟩 A. [2A][B]/[3C]

🟪 B. [A]²[B]/[C]³

🟨 C. [3C]/[2A][B]

🟦 D. [C]³/[A]²[B]✔️

2️⃣. Equilibrium constant value “Kc“ is equal to:

🟩 A. Qc/Kr

🟪 B. Kr/Kf

🟨 C. Kc/Qc

🟦 D. Kf/Kr✔️

3️⃣. NH₃ can be a base according to:

🟩 A. Arrhenius theory

🟪 B. Bronsted-Lowry theory

🟨 C. Lewis theory

🟦 D. both b and c✔️

4️⃣. Which of the following is a Lewis base?

🟩 A. HNO₃

🟪 B. AlCl₃

🟨 C. HCl

🟦 D. CN⁻✔️

5️⃣. The general formula of alkynes is:

🟩 A. CₙH₂ₙ

🟪 B. CₙH₂ₙ₊₁

🟨 C. CₙH₂ₙ₋₂✔️

🟦 D. CₙH₂ₙ₊₂

6️⃣. Which of the following is an alcohol?

🟩 A. CH₃CHO

🟪 B. CH₃CH₂OCH₃

🟨 C. CH₃CH₂OH✔️

🟦 D. HCOOH

7️⃣. Which one of the following is a polysaccharide?

🟩 A. Fructose

🟪 B. Maltose

🟨 C. Starch✔️

🟦 D. None

8️⃣. Cellulose content in cotton is:

🟩 A. 70%

🟪 B. 95%✔️

🟨 C. 85%

🟦 D. 90%

9️⃣. Ozone layer is part of the:

🟩 A. Stratosphere✔️

🟪 B. Mesosphere

🟨 C. Thermosphere

🟦 D. Troposphere

🔟It is Used to assess concentration of atomic/molecular/ionic species:

🟩 A. Chromatography

🟪 B. Spectroscopy✔️

🟨 C. Conductometry

🟦 D. Potentiometry

1️⃣1️⃣. Surfactants reduce the ______ of water.

🟩 A. Surface tension✔️

🟪 B. Viscosity

🟨 C. Boiling point

🟦 D. Melting point

1️⃣2️⃣. The centrifuge machine is used for separation of:

🟩 A. Crystals✔️

🟪 B. pH

🟨 C. Mud

🟦 D. Juice

1️⃣3️⃣. Insulin is basically a:

🟩 A. Enzyme

🟪 B. Hormone✔️

🟨 C. Starch

🟦 D. Mineral

1️⃣4️⃣. Vital force theory was introduced by:

🟩 A. Robert Boyle

🟪 B. J. J. Berzelius✔️

🟨 C. Lewis

🟦 D. Wohler

1️⃣5️⃣. Lactose enzymes are used:

🟩 A. In production of bread

🟪 B. To make ice cream sweeter✔️

🟨 C. To make alcohol

🟦 D. To maintain colour

✅ Answer Key with Short Reasons

1️⃣D — Products over reactants, coefficients become powers.

2️⃣D — Kc = Kf/Kr (ratio of forward and reverse rate constants).

3️⃣D — NH₃ accepts a proton (Bronsted) and donates lone pair (Lewis).

4️⃣D — CN⁻ has lone pairs → Lewis base.

5️⃣C — Alkynes general formula is CₙH₂ₙ₋₂.

6️⃣C — CH₃CH₂OH is ethanol (an alcohol).

7️⃣C — Starch is a polysaccharide.

8️⃣B — Cotton contains about 95% cellulose.

9️⃣A — Ozone layer lies in the stratosphere.

🔟B — Spectroscopy measures concentration via light interaction.

1️⃣1️⃣A — Surfactants lower surface tension.

1️⃣2️⃣A — Centrifugation separates crystals.

1️⃣3️⃣B — Insulin is a hormone.

1️⃣4️⃣B — Wohler disproved vital force, but Berzelius proposed it;

1️⃣5️⃣B — Lactase breaks lactose into sweeter sugars in ice cream.

1. Define any three of the following:

equilibrium constant, reaction quotient, extent of a reaction, pH, Indicator, Neutralization, Titration, alicyclic compounds, aromatic compounds, catenation, aldoses, ketoses, saccharides, functional group, Peptide linkage, saponification, lipids, enzymes, isomerism, Bloor’s reagent, fatty acid, ozone hole, organic chemistry, Biochemistry, Environmental chemistry, Analytical Chemistry, Qualitative Analysis, Quantitative Analysis, accuracy, precision, titrant, analyte, Indicator, parameter

2. Write down three differences between any one of the following:

(i) Troposphere and Stratosphere
(ii) reversible and irreversible reactions
(iii) saturated and unsaturated hydrocarbons
(iv) Dextrorotary and Levorotatory Sugars
(v) Quantitative analysis and qualitative analysis
(vi) Titrimetric analysis and gravimetric analysis
(vii) Classical and Instrumental Methods
(viii) fat and water-soluble vitamins.
(ix) DNA and RNA
(x) fat and oil
(xi) Aldoses and ketoses

3. Define chemical equilibrium state. Why chemical equilibrium is dynamic? Explain it with one example.

Describe the characteristics of equilibrium constant. Why equilibrium constant may or may not have unit? Justify with example.

4. Write down Equilibrium Constant Expression (K_c) and unit of K_c for any 3 of the following balanced reversible reactions.

(i) N₂_(g)+ 2O₂_(g) ⇌ 2NO₂_(g)

(ii) H₂_(g) + I₂_(g) ⇌ 2HI_(g)

(iii) CO₂_(g) + H₂_(g) ⇌ CO_(g) + H₂O_(g)

(iv) 2SO_2(g) + O_2(g)⇌ 2SO_3(g)

(v) N_2(g) + 3H_2(g)⇌ 2NH_3(g)

(vi) CO_(g) + 3H_2(g)⇌ CH_4(g)+ H₂O_(g)

6. State vital force theory and how was this theory discarded by Wohler?

Write the names and structural formulae of six carbons alkanes, alkenes, alkyne, cycloalkane and aromatic hydrocarbons.

Draw the structures of following compounds:

(i) 2,3-dimethylpentane

(ii) 3-ethyl-1-hexene

(iii) 2-butyne

(iv) 2,4-hexadiene

(v) 3-methyl-1,4-hexadiyne

(vi) 2-hepten-5-yen

(vii) 2-pentyne

(viii) neopentane

(ix) iso-propyl alcohol

(x) Phenol or toluene

(xi) iso-butane

(xii) Cyclohexane

8. Define salt and its three types with two examples each. Give three uses of salts. Also write any three methods of preparation of salts with equation.

OR Write one use of enzymes yeast, cellulase and amylase.

OR What is homologous series? Name the any two common homologous series with examples. Write down the general characteristics of homologous series.

What is alkyl radicals? Give its type formula and general formula. Explain with structure different radicals of butane. What is the difference of alkyl radicals obtained from propane?

9. Elaborate ionization equation of water. Explain in detail that how water ionization is related with pH of solution?

Define buffers. What is the composition of buffers? Discuss its importance in our daily life.

10. Write any three significant uses of Carbohydrates and lipids.

What are amino acids and peptide bond? How peptide bond is formed? Also explain dipeptides & tripeptides.

11. Give reason:

(i) Why Silicon compounds are lesser than that of Carbon compounds?

(ii) Why pure water is considered as weak electrolyte?

(iii) Justify the petroleum is ‘black gold’.

(iv) Alkanes are said to be saturated hydrocarbons.

(v) Justify that water soluble vitamins are not injurious to health.

(vi) Justify that greenhouse effect leads to global warming

(vii) Justify that “water is solvent”.

(viii) How is vegetable oil is converted into saturated fat (ghee)?

(ix) Why chemical equilibrium is considered dynamic not static?

(x) Why the temperature on top of a mountain is colder than at sea level?

13. What are Oligosaccharides, Disaccharides and polysaccharides. Give their examples and sources.

What are the carbohydrates? Explain sources and types of carbohydrates.

14. What are amino acids and give their general structure? How many Essential and Non-essential Amino acids are there? Write down the range of Number of Amino acids and molecular weights of Proteins

What are fatty acids? Give their examples and chemical nature.

15. Briefly describe any three beneficial impacts of pharmaceutical industry on human society.

16. Write down causes of following diseases:

(i) Diarrheal Diseases

(ii) Dysentery

(iii) Cholera

(iv) Crytosporidium

(v) Fluorosis

(vi) Hepatitis

(vii) Hookworm

(viii) Typhoid

17. What is the cause of acid rain? Explain. Write down the effects of acid rain and global warming.

What are primary and secondary air pollutants? Or Give difference between primary and secondary air pollutants. Identify as primary or secondary air pollutant SO₂, CH₄, HNO₃, NH₃, H₂SO₄ and O₃

18. Describe the composition of water. Write degree of Hardness of water on the basis of Dissolved Ca Ions (mg/L)

19. List down the applications of conductometry?

Describe the composition of water. Write down degree of Hardness of water on the basis of Dissolved Ca Ions.

20. What is error? Write down causes of errors with their %. Write down brief note systematic and random errors with two examples each.

Describe fractional distillation of petroleum with its 5 fractions.

21. A solution of HCl has pH of 2.3. Calculate its pOH and [H⁺]?

Find pH, pOH, [OH⁻] and [H⁺] of 2.46 × 10⁻⁹ M KOH solution.

22. State law of mass action and define K_c. Derive an expression for equilibrium constant for a general reaction.

23. State and explain Bronsted-Lowry acid-base theory or Lewis concept of acids and bases with examples? explain with an example that water is a Bronsted-Lowry acid as well as Bronsted-Lowry base. OR

State three different theories about concepts of acids and bases with one example and also indicate one limitation of each concept. Which of the following is/are Arrhenius acids and bases?

(a) Ca(OH)₂ (b) HNO₃ (c) NaOH (d) H₂SO₄ (e) KOH

24. Define functional group. Write different functional groups which contain carbon, hydrogen and oxygen.

Define nomenclature and describe IUPAC nomenclature rules for alkynes and alkanes. Write down IUPAC names of following:

25. What are the main sources of organic compounds? Mention with special reference of coal, petroleum and natural gas.

What do you mean by diversity and magnitude of organic compounds? Give at least 5 reasons.

26. What are Lipids? Write down the sources and uses of lipids. Write five differences between Fats and Oils.

What are proteins and peptide bond? How peptide bond is formed in dipeptides and tripeptides ? Write down the range of Number of Amino acids and molecular weights of Proteins. Give importance and sources of proteins.

27. Describe in detail nucleic acids, RNA and DNA. Write down importance of deoxyribonucleic acid (DNA).

28. Describe process of Saponification with the help of flow sheet diagram.

Describe fractions of petroleum in detail.

29. Justify that electrochemical methods depend upon electrochemical cells.

OR What is Titrimetric Analysis? Describe how it is performed with diagram.

30. Explain the process of preparation sugar from sugar cane. OR Describe process of Saponification with the help of flow sheet diagram.

31. What is Ozone? How does Ozone depletion occur by Chlorofluorocarbons (CFCs) also mention some adverse impact of it?

OR Describe global warming. Justify that greenhouse effect leads to global warming.

32. Describe Gas Chromatography with diagram also write two uses of gas chromatography.

33. What are Soft Water and Hard Water and describe different methods of removing temporary and permanent hardness. Write down 5 disadvantages of hard water.

34. Definition Water Pollution. Write down its Causes and Effects on Life

35. For the reaction, H_2(g) + I_2(g) ⇌ 2HI_(g)(K_c = 57.0); the concentrations of H_2(g), I_2(g) and HI_(g) at time t are:

[H₂]_t = 0.10 mol dm⁻³,

[I₂]_t = 0.20 mol dm⁻³,

[HI]_t = 0.40 mol dm⁻³

Predict in which direction reaction will move to achieve equilibrium.

(Answer; Q_c (8.0) is less than K_c (57.0), reaction will move in the forward direction)

Equilibrium occurs when nitrogen monoxide gas reacts with oxygen gas to form nitrogen dioxide gas

2NO_(g) + O_2(g) ⇌ 2NO_2(g)

At equilibrium at 230^oC, the concentrations are measured to be

[NO] = 0.0542 mol dm⁻³,

[O₂] = 0.127 mol dm⁻³

and

[NO₂] = 15.5 mol dm⁻³

Calculate the equilibrium constant at this temperature. (Book problem 1; page 8)(Answer; 6.44 x 10⁵ mol^-1 dm³)

🧪📚 Answers of Section-B (Short-Answer Questions)

1. Define any three of the following:

Active mass, Equilibrium constant, reaction quotient, extent of a reaction, pH, Indicator, Neutralization, Titration, alicyclic compounds, aromatic compounds, catenation, aldoses, ketoses, saccharides, functional group, Peptide linkage, Saponification, lipids, enzymes, isomerism, Bloor’s reagent, fatty acid, ozone hole, organic chemistry, Biochemistry, Environmental chemistry, Analytical Chemistry, Qualitative Analysis, Quantitative Analysis, accuracy, precision, titrant, analyte, Indicator, parameter

Answer

Active Mass

The Molar Concentration in mol/dm³ or mol dm⁻³ (mol/litre) of substances is termed as ACTIVE MASS which represented by square brackets; [ ].

Equilibrium Constant (Kc)

The equilibrium constant (Kc) of a reversible reaction is a constant ratio of Kf/Kr (specific rate constant for forward reaction/specific rate constant for reverse reaction) at constant temperature. Equilibrium constant is a ratio of the product of the equilibrium molar concentrations (active masses) of products to the product of the equilibrium molar concentrations (active masses) of reactants with each concentration term raised to the power of coefficient as expressed in the balanced chemical equation at constant temperature.

Reaction Quotient (Q or Qc)

It is the ratio of initial concentration of products and initial concentration of reactants (not necessarily at equilibrium).

Extent of a reaction

The extent of reaction is the limit up to which reactants are changed to products. It indicates to which extent reactants are converted to products.

pH is a measurement of the concentration of hydrogen ions (H⁺) in a solution. pH is an abbreviation for power of H⁺ ion concentration. pH of a solution is defined as the negative logarithm of the molar hydrogen ions concentration [H⁺] (in mol/litre) of a solution. pH values range from 0-14.

pH = – log [H⁺]

Indicators

Indicators are complex the weak organic acids or bases which change colour over small range of pH in acidic or basic medium and by means of it end-point can be detected during acid-base titrations. They have different colours in acidic and alkaline solutions. Litmus is a common indicator. It is red in acidic solutions and blue in alkaline solutions.

Neutralization

When Arrhenius acid and Arrhenius base reacts, salt and water is formed as product, the reaction is known as neutralization reaction. For example:

Titration

Titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution. Typically, the titrant (the known solution) is added from a burette to a known quantity of the analyte (the unknown solution) until the reaction is complete.

Accuracy

The accuracy of analytical method is the closeness of obtained value to the true value of a sample. For example if we weight 2.5 mg of sample or substance but actual or known weight of sample is 10mg then this measurement is not accurate.

Acyclic Compounds or Aliphatic compounds or Open Chain Compounds

Open chain compounds contain carbon atoms linked in open chain. Open chain compounds are those in which the end carbon atoms are not joined with each other, in this way they form a long chain of carbon atoms. Open chain compounds are also called aliphatic compounds. e.g. n-pentane, isopentane etc.

Aldose Sugars

The carbohydrates which contain aldehydic group are called aldoses

Ketose Sugars

The carbohydrates which contain ketone group are referred as ketoses.

Alicyclic or Non-benzenoid Compounds

Carbocyclic compounds which do not have benzene ring in their molecules are called alicyclic or non-benzenoid compounds.

Analytical Chemistry

The analysis and separation of sample to detect and estimate its components through various techniques and instruments is known as analytical chemistry. It deals with instruments and methods to separate, identify and quantify the matter.

Aromatic Compounds/ Benzenoid Compounds

These organic compounds contain at least one benzene ring with six carbon atoms in their molecule. A benzene ring is made up of six carbon atoms with three alternating double bonds. They are called aromatic because of aroma or smell they have. e.g. benzene and naphthalene

Biochemistry

The word Biochemistry (Bio = Life + Chemistry) means chemistry of life. This branch of chemistry deals with the study of with the naturally occurring macromolecules such as carbohydrates, proteins, lipids, nucleic acids and vitamins and various chemical and physical processes inside living system or organisms (plants and animals). It focuses on what is happening inside our cells and looks at how cells communicate with each other.

Enzymes

The word enzyme has a Greek origin which means that “in the yeast”. Enzymes are the class of proteins which are the complex polymeric nitrogenous organic biocatalysts produced by living cells that catalyze all types of biochemical reactions like digestion, respiration, muscular contraction and metabolism taking place in the living organisms. They are macromolecule that makes an unfavourable reaction able to occur. They accelerate the biochemical reactions and lead these reactions to completion which is not possible at ordinary temperature.

Peptide Linkage

The acid-amide (-CO-NH-) bond through which amino acids are linked in proteins by eliminating a water molecule is called Peptide Linkage. Due to this linkage protein is formed. When thousands of amino acids polymerize they form protein. A protein molecule formed with two amino acids is termed as dipeptide, with three tripeptide and so son. This linkage is formed by the removal of a water molecule b/w an -NH₂ group of an amino acid and -COOH group of another.

Fatty acids

Fatty acids are naturally occurring non-branched aliphatic monocarboxylic acids consisting of a long saturated or unsaturated lengthy hydrocarbon chain with a terminal carboxylic group mostly obtained from hydrolysis of natural fats and oils containing even number of carbon atoms (ranges C₁₂-C₂₀). They are long chain saturated or unsaturated carboxylic acids with a lengthy chain, either saturated or unsaturated. Fatty acids form esters (oils or fats) and glycerol in the presence of mineral acids. Fatty acids are building blocks of lipids. e.g. Palmitic acid; C₁₅H₃₁COOH, Stearic acid; C₁₇H₃₅COOH

Functional Group

An atom or group of atoms or multiple bonds which gives distinctive characteristic properties to an organic molecule is called functional group e.g. –OH group is the functional group of alcohol family (R–OH).

Isomerism

It is a phenomenon where two or more compounds have the same molecular formula but possesses different structural formulas and different properties. This is mainly because of different structural or spatial arrangements. Carbon compounds show phenomenon of isomerism by virtue of which a single molecular formula may represent two or more compounds.

Lipids

The lipids are a group of naturally occurring heterogeneous, water-insoluble, non-polar organic compounds of the plant and animal origins which includes fats, oils, waxes, and are insoluble in water but are easily soluble in Bloor’s reagent (a mixture of diethyl ether and ethyl alcohol in the ratio of 2:1) and organic solvents like ether, benzene, acetone, carbon tetrachloride and chloroform.

Catenation

The property of forming bonds with atoms of the same element is called catenation. It is the self-linking property of carbon.

Saccharides

Saccharides commonly known as Carbohydrates are naturally occurring organic compound are important food factor. Carbohydrates are macromolecules defined as polyhydroxy aldehydes or polyhydroxy ketones or large molecules that give these compounds on hydrolysis. They generally contain elements like carbon, hydrogen and oxygen.

Saponification

The chemical process for the preparation of soap is called saponification which is the reaction of triglycerides or fats or oils with sodium or potassium hydroxide to form glycerol and fatty acid salt called soap.

Lipids

Lipids are a group of naturally occurring heterogeneous organic compounds which includes fats, oils, waxes, and are insoluble in water but easily soluble in Bloor’s reagent (mixture of diethyl ether and ethyl alcohol in the ratio of 2:1) and organic solvents like ether, benzene, acetone, carbon tetrachloride and chloroform.

Bloor’s reagent

Bloor’s reagent is mixture of diethyl ether and ethyl alcohol in the ratio of 2:1 and it is used as a solvent for lipids.

Ozone hole

The ozone hole is a location where the ozone layer is depleted.

Organic chemistry

The study of covalent compounds of carbon and hydrogen (hydrocarbons) and their derivatives is called Organic Chemistry. All organic compounds contain carbon as an essential element. In short, it is chemistry of carbon containing compounds.

Environmental chemistry

Environmental Chemistry is the scientific study of the chemical and biological phenomena that occur in natural places. It is the field of chemistry deals with the study of reactions, origins, interactions, transport, effects along with the fates of all the chemical species present in the soil, water, and air environments, as well as the impact of human and biological activities on these.

Analytical Chemistry

The analysis and separation of sample to detect and estimate its components through various techniques and instruments is known as analytical chemistry. Analytical chemistry deals with instruments and methods to separate, identify and quantify the matter.

Qualitative Analysis

The identification of elements, ions or compounds present in a sample focusing only quality of substance is called Qualitative analysis.

Quantitative Analysis

The determination of exact amount of quantity of one or more substance present in compound or sample is called quantitative analysis. It deals with large number quantifying methods which are classified as physical or chemical methods.

Precision

The degree of agreement between replicate measurements of the same quantity is called precision. It is repeatability of a result and known as degree of exactness. Precision is measured how much detailed information is given and how much exactly measurement was taken.

Titrant

A titrant is a solution of known concentration that is added to another solution to determine the concentration of a second chemical species for example NaOH, HCl.

Anaylate

A chemical substance that is subject of chemical analysis or whose constituent are going to be measured is called analyte. For example 24 karat gold, NaCl, water etc.

Parameter

The parameter is measurable factor or boundary which define performance and quality of analytical methods. The validation a of analytical method is observed by parameters and various parameters of validation are selectivity, linearity, range, accuracy, precision and error.

2. Write down three differences between any one of the following:

(i) Saturated and unsaturated hydrocarbons

(ii) Fat and oil

(iii) Fat and water-soluble vitamins

(iv) Dextrorotary and Levorotatory Sugars

(v) Quantitative analysis and qualitative analysis

(vi) Reversible and irreversible reactions

(vii) Classical and Instrumental Methods

(viii) Troposphere and stratosphere

Answer

3. Define chemical equilibrium state. Why chemical equilibrium is dynamic? Explain it with one examples

Answer

Definition of Chemical Equilibrium

Chemical Equilibrium is the state of a reversible reaction (in a closed vessel) at which there is no observable change in the concentrations of reactants and products with time and rate of forward reaction is exactly equal to the rate of reverse reaction. Thus at equilibrium state:

Rate of forward reaction = Rate of backward reaction and Concentration remain constant

Chemical Equilibrium as Dynamic Equilibrium

The chemical equilibrium is dynamic in nature as both forward and reverse reactions are still occurring with same speed at all times even though the rates and concentrations are constant. Neither the forward reaction nor the reverse reaction has ceased to occur.

Example of attainment of equilibrium for hydrogen iodide formation form hydrogen and iodine

An example of reaction at equilibrium is a reaction of hydrogen and iodine vapours in a closed container to produce hydrogen iodide. At the start of reaction, there is a higher concentration of hydrogen and iodine and after that the concentration decreases as hydrogen iodide is formed. The concentration of hydrogen iodide increases as the forward reaction proceeds. As hydrogen iodide is formed, the reverse reaction is then able to occur. consequently the rate of the forward reaction will go on decreasing and the reverse reaction will go on increasing and ultimately the two rates will become equal to each other. Thus, the equilibrium will set up and concentration of various species (H₂, I₂, HI) becomes constant. It is represented as

Describe the characteristics of equilibrium constant. Why equilibrium constant may or may not have unit? Justify with example.

Answer

The equilibrium constant (Kc) of a reversible reaction is a constant ratio of Kf/Kᵣ (specific rate constant for forward reaction/specific rate constant for reverse reaction) at constant temperature. Equilibrium constant is a ratio of the product of the molar concentrations (active masses) of products to the product of molar concentrations (active masses) of reactants with each concentration term raised to the power of coefficient as expressed in the balanced chemical equation at constant temperature. Thus Kc is directly proportional to molar equilibrium concentrations (active masses) of products and inversely proportional to molar equilibrium concentrations (active masses) of reactants.

For a general reversible reaction; aA + bB ⇌ cC + dD, Kc is given by

Factors affecting value of Kc

The value of equilibrium constant does not depend on the initial concentrations of the reactants and the products. The value of Kc depends only on temperature i.e.

Importance of Kc

Kc determines which in greater concentration at equilibrium – the products or the reactants. In general:

(i) Kc > 1; equilibrium lies to the right and favours the product.

(ii) Kc < 1; equilibrium lies to the left and favours the reactants.

Unit of Kc

1. Kc has no units in reactions with equal number of moles on both sides of the equation. This is because concentration units cancel out in the expression for Kc.

e.g.

For the reaction; CO₂ (g) + H₂ (g) ⇌ CO₂ (g) + H₂O(l), Kc has no unit as the number of moles of reactants and products are equal in the balanced chemical equation. the unit of Kc is derived as

2. Kc has a unit for reactions when the number of moles of reactants and product are not equal,

e.g.

For the reaction; N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g); where the number of moles of reactants and products are not equal in the balanced chemical equation. the unit of Kc is derived as

6. State vital force theory and how was this theory discarded by Wohler?

Answer

Vital Force Theory

In 1885, Swedish chemist Jacob Berzelius put forward the “Vital Force Theory”. According to Vital Force Theory:

Organic compounds can only be formed in the tissues of living organisms (plants and animals) under the influence of a mysterious force called Vital Force, and cannot be synthesized form inorganic substances in the laboratory.

Demise (Rejection) of Vital Force Theory

In 1828, a German chemist Friedrich Wohler accidentally prepared the first organic compound Urea in the laboratory from an inorganic compound ammonium cyanate. Urea is a typical organic compound excreted in the urine of mammals.

Write the names and structural formulae of six carbons alkanes, alkenes, alkyne, cycloalkane and aromatic hydrocarbons.

Answer

Draw the structures of following compounds:

(i) 2,3-dimethylpentane

(ii) 3-ethyl-1-heptene

(iii) 1-butyne

(iv) 2,4-hexadiene

(v) 3-methyl-1,4-hexadiyne

(vi) 2-hepten-5-yn

(vii) 2-pentyne

(viii) neopentane

(ix) iso-propyl alcohol

(x) Phenol or toluene

(xi) iso-butane

(xii) Cyclohexane

Answer

7. Write down the molecular, structural and condensed formulae of the following compounds:

Answer

Define functional group. Identify the functional groups in the following compounds and also write their names:

(a) CH₃CHO (Aldehydic group)

(b) CH₃CH₂CH₂OH (primary alcoholic group)

(c) CH₃COCH₃ (ketonic carbonyl group)

(d) C₃H₇COOH (carboxylic group)

(e) CH₂=CHCH₃

(f) CH₃COOCH₂CH₃ (ester group)

(g) CH₃CH₂Cl (chloride group)

(h) CH₃OCH₃

Answer

Functional Group

An atom or group of atoms or multiple bonds whose existence in an organic compound gives distinctive qualities to that compound is called a functional group.

Identification of Functional Group

8. Define salt and its three types with two examples each. Give three uses of salts. Also write any three methods of preparation of salts with equation.

Answer

Definition of Salt

A salt is an ionic crystalline compound which is the neutralization product (other than water) of an acid and base and it is the aggregation of cation (from base) other than H⁺ and anion (from acid) other than OH⁻. NaCl, CuCl₂ etc.

Three Types of Salts

1. Normal Salts (Salts obtained by complete neutralization of acid and base) e.g. NaCl, KNO₃, Na₂SO₄, K₃PO₄ etc.

2. Acidic Salts (Salts obtained by partial neutralization of an acid by a base) e.g. NaHCO₃, NaHSO₄, NH₄Cl etc.

3. Basic Salts (Salts obtained by partial neutralization of a base by an acid) e.g. Mg(OH)Cl, KCN, K₂CO₃ etc.

Three Uses of Salts

1. Chemical fertilizers used in agriculture by farmers are salts e.g. ammonium chloride, potassium chloride

2. Pesticides to kill or destroy insects, pests, weeds and fungi are salts e.g. copper(II) sulphate, iron(II) sulphate

3. Iron(II) sulphate heptahydrate (FeSO₄.7H₂O) in ‘iron pills’ is used for anemic patients.

4. Sodium hydrogen carbonate is used as a anti-acid to neutralize the excess acid secreted by the stomach.

5. Potassium permanganate(VII) is used as a disinfectant to kill bacteria.

6. In medical field, hydrated calcium sulphate (CaSO₄.2H₂O) is found in Plaster of Paris to make plaster casts for supporting broken bones.

7. Barium sulphate is used to make barium meals for patients who need to take an X-ray of their stomach. The salt helps to make internal organs like intestines appear on X-ray films.

Three Methods for the Preparation of Salts

Salts are prepared by the action of acids on metals, metal hydroxide (bases or alkalis), metal oxides, metal carbonates and metal bicarbonates. Salts are produced by the action of a base on a metal.

Write one use of enzymes yeast, cellulose and amylase.

Answer

(i) yeast is used in the fermentation of molasses and starch to make alcohol (Ethanol).

(ii) cellulase is used in detergents to break down cellulose into water-soluble glucose

(iii) amylase is used as a sweetener in cuisine as well as in the baking of bread.

What is homologous series? Name the any two common homologous series with examples. Write down the general characteristics of homologous series.

Answer

Definition of Homologous Series

Organic compounds are classified into classes based on the chemical properties. Each group or class is called homologous series which is a family or set of similar organic compounds having a same functional group which follows a regular structural pattern in which each successive members have a common difference of methylene (>CH₂) [or by molecular mass of 14]. Each member of series is called a Homologue of the other”. (in Greek, homo means same and logous means ratio).

Examples

General characteristics of homologous series

1. Identical structures and common difference in composition

Successive members of the series differ by one unit of -CH₂- and 14 units in their relative molecular mass. All members of a homologous series have identical structures.

2. General Molecular Formula

All members of a homologous series can be expressed by a general molecular formula.

For example

general formulae of alkane, alkenes and alkynes are CₙH₂ₙ₊₂, CₙH₂ₙ and CₙH₂ₙ₋₂, respectively.

3. General Method of Preparation

All members of a homologous series can be prepared by a similar manner called general method of preparation

e.g. all members of alkanes can be prepared by reduction of alkyl halide by nascent hydrogen [H]:

4. Identical Chemical Properties

They have similar chemical properties because they contain the same functional group.

e.g. all alkanes are unreactive under ordinary conditions. They undergo combustion and substitution reaction with halogens.

What is alkyl radicals? Give its type and general formula. Explain with structure different radicals of propane & butane.

Answer

Definition of Alkyl Radicals

The radicals obtained from alkanes by the removal of one hydrogen atom are called alkyl group or radical. They are generally represented by “R–” with general formula CₙH₂ₙ₊₁. Alkyl radicals are derivatives of alkanes.

Propyl Radical (It may exist in two isomeric forms)

Propane has a straight chain structure. When terminal H is removed, it is called n-propyl. When hydrogen from central carbon is removed, it is called isopropyl, as explained below:

Butyl Radical

Butyl radical is derived from butane (C₄H₁₀) having formula C₄
H₉–. It may exist in 4 isomeric forms.

Butane has two isomers namely straight chain n-butane and branched chain iso-butane which gives total four isomeric alkyl groups, 2 are primary, 1 is secondary and 1 is tertiary.

n-butane has two types of carbon atoms i.e. primary and secondary so it gives two alkyl groups. Iso-Butane has primary and tertiary carbon so it gives two alkyl groups.

Details

When terminal H is removed from primary carbon of n-butane, it is called n-butyl/primary-butyl denoted as 1°.

When hydrogen from central or secondary carbon is removed from n-butane, it is called sec-butyl denoted as 2°.

When terminal H is removed from primary carbon of iso-butane, it is called iso-butyl.

When hydrogen from central or tertiary carbon is removed from iso-butane, it is called tert-butyl denoted as 3°.

9. Elaborate ionization equation of water. Explain in detail that how water ionization is related with pH of solution?

Answer

The water is a neutral liquid which has equal number of hydrogen (H⁺) and hydroxide (OH⁻) ion. Water is a weak electrolyte because it ionizes very slightly into ions in a process called auto-ionization or self-ionization which is characterized by an equilibrium constant (Kc) at a given temperature. Since a very small fraction of water molecules are ionized, the concentration of unionized water molecules is in large excess and is virtually constant. we can write the equilibrium (Kc) expression for auto-ionization for water as:.

H₂O ⇌ H⁺ + OH⁻ (auto-ionization equilibrium)

The equation constant (Kw) is called Ionic Product of water or Ionic-Product constant or Dissociation constant of water and it is equal to 1 x 10⁻¹⁴ (mol dm⁻³) ² or mol² dm⁻⁶. This constant determines absolutely the relative [H⁺] and [OH⁻] ions in water at this temperature. In pure water at 25°C, concentration of H⁺ and OH⁻ ions would always be equal and found to be 1 x 10⁻⁷ mol/dm³ (M). [That is why water is neutral at 25°C].

If the solution is acidic, then [H⁺] > [OH⁻] and if the solution is basic then [H⁺] < [OH⁻] but the ionic product Kw remains constant at 1 x 10⁻¹⁴ M² at 298K. For neutral solution [H⁺] = [OH⁻] =1 x 10⁻⁷ M. This [H⁺] is related with pH which is the negative log of [H⁺].

Define buffers. What is the composition of buffers? Discuss its importance in our daily life.

Answer

Buffer

A buffer is an aqueous solution that has a highly stable pH and that can resist pH change upon the addition of acid or base. It is able to neutralize small amounts of added acid or base thus maintaining the pH of solution relatively stable. The pH of a buffer is independent of ionic strength. The pH of a buffer is dependent on temperature.

A buffering agent is a weak acid and its salt (conjugate base) with strong base or weak base and its salt (conjugate acid) with strong acid that helps to maintain the pH of an aqueous solution after adding another acid or base.

Two Types of Buffer or Composition of Buffer

1. Acidic buffer

They are made from weak acid and its salt with strong base (conjugate base)

e.g. CH₃COOH (weak acid)- CH₃COONa (salt or conjugate base)

2. Basic buffer

They are made from weak base and its salt with strong acid (conjugate acid)

e.g. NH₃ (weak base)-NH₄Cl (salt or conjugate acid)

Importance of Buffers

1. Maintenance of pH of Blood using combination of carbonate (H₂CO₃/NaHCO₃), phosphate (Na₂HPO₄ /NaH₂PO₄) and protein buffer systems.

2. Maintenance of pH in Laboratory Reactions

3. Maintenance of pH in various Industries like tanning of leather, manufacture of sugar, paper, drugs etc.

4. For Preparing Culture Media in Biological and Pathological Laboratories to maintain a constant pH for suitable growth of bacteria and viruses.

5. For Good Yield of Crops

6. For Preservation of foods and Fruits

7. Use in Other Sciences like molecular biology, microbiology, cell biology, soil sciences, nutrition & clinical analyses.

10. Write any three significant uses of Carbohydrates and lipids.
Answer
Three Uses of Carbohydrates
1. They are main energy providing materials or energy source for the survival of both plants and animals.
2. They sustain plant structure.
3. Carbohydrates, in the form of starch in plants and glucose in mammals, serve as energy storage.

Three Uses of Lipids
1. They act as transporter of fatty acids and fat soluble vitamins (A, D, E and K) in body.
2. They activate the enzymes.
3. Fats and oils are used for cooking and frying of food.

OR
What are amino acids and peptide bond? How peptide bond is formed? Also explain dipeptides & tripeptides.
Answer
Amino acids
Amino acids are building blocks of protein which are bi-functional organic compound containing an acidic carboxyl (–COOH) and a basic amino (–NH₂) groups and a distinct side chain ‘R’ which is different for different amino acids.

Peptide Bond or Linkage
A peptide linkage is an acid-amide bond formed between amino acids by the elimination of water. Due to this linkage protein is formed. When thousands of amino acids polymerize they form protein.

Formation of Peptide Bond

Dipeptides and tripeptides
A protein molecule formed with two amino acids is termed as dipeptide.
A protein molecule formed with three amino acids is termed as tripeptide.

11. Give reason:

Answer

(i) Why Silicon compounds are lesser than that of Carbon compounds?

Silicon compounds are less diverse than carbon compounds because silicon atoms are larger allowing lesser degree of catenation making it harder to form long chains and stable bonds. C–C bonds are much stronger (355 kJ mol⁻¹) than Si–Si (200 kJ mol⁻¹) bonds.

(ii) Why pure water is considered as weak electrolyte?

Pure water is considered as weak electrolyte because it gives very few ions on auto-ionization due to strong hydrogen bonding.

(iii) Justify the petroleum is ‘black gold’.

Petroleum is natural substance trapped in rocks beneath the Earth’s crust. The term petroleum refers to rock oil. Water, salts and earth particles are all present in this complex combination of gaseous, liquid and solid hydrocarbon. It is a liquid that is lighter than water yet insoluble in it.

Petroleum is referred to as 'black gold' because when black coloured crude oil extracted from the land is refined to give golden coloured distillate which worth like a gold due its oils and value. It is in less amount but economic value is extreme.

(iv) Alkanes are said to be saturated hydrocarbons.

Alkanes are said to be saturated hydrocarbons because they contain only C-C single bond with maximum number of hydrogen atoms having no scope of addition of any other atoms due to complete saturation of all the four valencies of carbon atom.

(v) Justify that water soluble vitamins are not injurious to health.

Water-soluble vitamins are rapidly excreted from the body. Hence, these vitamins are not toxic even if taken in large quantity. However, their deficiency causes disease.

(vi) Justify that greenhouse effect leads to global warming

Global warming refers to the gradual rise in Earth’s average surface temperature. The greenhouse effect or quantity of CO₂ in the air has a direct relationship with global warming effect. The greater the amount of CO₂, the greater the heat trapping or warming resulting in progressive rise in the surface’s average temperature leading to global warming.

(vii) Justify that “water is solvent”.

Water is a remarkable and excellent solvent and it is called Universal Solvent as it has the ability to dissolve practically all minerals. The high dissolving power of water is attributed due to its two distinct properties:

(i) Polar nature of water

(ii) Its extensive hydrogen bonding ability (Solvating tendency)

(viii) How is vegetable oil is converted into saturated fat (ghee)?

Vegetable oils are triester of glycerol and fatty acids of unsaturated long chains. Vegetable oil is converted into saturated fat ghee by the chemical process called hydrogenation. In this process unsaturated vegetable oil is treated with molecular hydrogen (H₂) in the presence of catalyst like nickel (ni) or palladium (Pd) at 250-300°C to form vegetable ghee (fat). This is an addition reaction of oil with H₂ to form an adduct called fat.

(ix) Why chemical equilibrium is considered dynamic not static?

Chemical equilibrium is considered dynamic because at equilibrium both forward and reverse reactions are taking place with same rate but in opposite directions. Since both reactions are not stopped, equilibrium is not static.

(x) Why the temperature on top of a mountain is colder than at sea level?

the temperature on top of a mountain is colder than at sea level due to low air density due to which its molecules are spread apart on account of decreased atmospheric pressure leading to fall in temperature.

12. Complete the following neutralization reactions between acids and bases.

Answer

(i) Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O

(ii) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

(iii) 3NaOH + H₃PO₄ → Na₃PO₄ + 3H₂O

Define vitamin and complete the following chart

Answer

13. What are Oligosaccharides, Disaccharides and polysaccharides. Give their examples and sources.

What are the carbohydrates? Explain sources and types of carbohydrates.

Answer

Definition of carbohydrates

Carbohydrates are naturally occurring organic compound are important food factor. Carbohydrates are macromolecules defined as polyhydroxy aldehydes or polyhydroxy ketones or large molecules that give these compounds on hydrolysis. They generally contain elements like carbon, hydrogen and oxygen.

General formula

They have general formula Cₙ(H₂O)ₙ showing that these compound contain hydrogen and oxygen in the ratio as in H₂O i.e. 2:1 (although they do not contain water molecules).

Classification of carbohydrates based on hydrolysis

Carbohydrates are classified as into three types based on hydrolysis:

Monosaccharides (Greek; Mono = one)

Definition

Monosaccharides are the simplest sugars which cannot be further simplified on hydrolysis.

No of Carbon atoms

They consist of 3 to 10 (9) carbon atoms.

Properties

Monosaccharides are white crystalline solids. They are soluble in water and have sweet taste. They cannot be hydrolyzed. They are reducing in nature, therefore, these are called reducing sugars.

Types

They are further classified according to the number of carbon atoms in their molecules as trioses, tetroses, pentoses, hexoses, and so on.

The important monosaccharides are hexoses like glucose and fructose, etc.

Glucose

1. Glucose (grape sugar) belongs to aldoses and fructose (honey) to ketones are examples of monosaccharides.

2. Glucose is obtained naturally as dextrorotatory and is present in grapes (20-30%), honey. It is also found in combined state in cane sugar, starch and cellulose.

3. Glucose is a rapid source of energy for patients. Fructose (Latin; fructus = fruit) occurs in ripe fruits, honey, cane sugar etc.

4. Glucose is a necessary component of human blood, that is why it is also known as blood sugar. The normal range for blood glucose is 65-110 mg (0.06-0.1%) per 100 mL.

5. Glucose is a pentahydroxy aldehyde (aldo hexose) while fructose is pentahydroxy ketone (keto hexose) having the open chain structures as follows and general formula C₆H₁₂O₆

Oligosaccharides (Greek; Oligo = few)

Definition

Oligosaccharides give 2 to 10 (9) units of monosaccharides on hydrolysis. In oligosaccharides, monosaccharides are linked with each other by glycosidic bond or linkage.

Properties

Oligosaccharides like monosaccharides are white, crystalline solids, sweet in taste and easily soluble in water. (They may be reducing or non-reducing).

Types

They are classified as disaccharides, trisaccharides, tetrasaccharides etc., depending upon the number of monosaccharides units they produce on hydrolysis.

Disaccharides

Disaccharides are those oligosaccharides which contain two monosaccharides. The most important oligosaccharides are disaccharides like sucrose. On hydrolysis, sucrose produces one unit of glucose and one unit of fructose.

Examples

Sucrose, maltose, lactose (milk sugar) are important members of disaccharides.

Polysaccharides

Definition

Polysaccharides are macromolecular carbohydrates also called polymeric carbohydrates giving more than 10 monosaccharides on hydrolysis consisting of hundreds to thousands of monosaccharides linked by glycosidic linkage.

Properties

Polysaccharides are amorphous, tasteless and insoluble in water. They are non-reducing in nature.

Examples of polysaccharides

1. Cellulose, starch (plant origin), glycogen (animal origin), amylose etc. are common polysaccharides. Cellulose is found in the cell walls, wood, linen, paper, cotton etc. Cotton contains 95% cellulose.

2. Starch occurs in cereals like wheat, rice, barley etc. and roots of potatoes.

3. Glycogen is also called animal starch found in muscles and liver of animals

Sources of Carbohydrates

14. What are amino acids and give their general structure? How many Essential and Non-essential Amino acids are there? Write down the range of Number of Amino acids and molecular weights of Proteins

Answer

Amino acids are building blocks of protein. They are bi-functional organic compound containing an acidic carboxyl (–COOH) and a basic amino (–NH₂) groups and a distinct side chain ‘R’ which is different for different amino acids.

Number of Amino acids in Proteins ----------- 60 to 6000 amino acids molecules.

molecule weight of proteins -------------------- 43000-50,000,000 daltons (1 dalton = 1amu).

Total Amino acids…………………………………….. 20

Essential Amino acids ……………………………… 10

Non-essential Amino acids………………………. 10

What are fatty acids? Give their examples and chemical nature.

Answer

Definition of Fatty acids

Fatty acids are building blocks of lipids. They are long chain saturated or unsaturated carboxylic acids with a lengthy chain, either saturated or unsaturated. Fatty acids form esters (oils or fats) and glycerol in the presence of mineral acids.

Examples of Fatty acids

1. Palmitic acid; C₁₅H₁₃COOH

2. Stearic acid; C₁₇H₅₃COOH

Chemical Nature

Lipids are macromolecules made up of fatty acids. Lipids include oils and fats. Oils and fats are triesters of long chain carboxylic (fatty) acids with glycerol. These esters are made of three fatty acids, therefore, they are called triglycerides or triesters. General formula of triglycerides is as under.

15. Briefly describe any three beneficial impacts of pharmaceutical industry on human society.

Answer

Importance of Pharmaceutical Industry

Pakistan’s pharmaceutical business has risen significantly in recent decades. Pharmaceutical forms are always working on novel therapies that will help people live longer, healthier lives. Here are some of the industry’s most important contributions, as well as why pharmaceutical firms are so vital to patients, society, and the life sciences industry.

1. Treatments increase life expectancy

The pharmaceutical business has made a significant contribution to the global increase in life expectancy for men and women. Pharmaceutical improvements are said to have responsible for 73% of the entire increase in life expectancy between 2000 and 2009 in 30 developing and high-income nations.

2. The industry strives to eradicate and eliminate diseases

When it comes to creating remedies, the ultimate objective is disease elimination, as this helps ecosystems on a worldwide scale. Smallpox is the first and so far only – human illness to be declared eliminated globally, according to the World Health Organization (WHO).

3. Reduced pain and suffering

According to a research conducted by the World Health Organization, people who live with chronic pain are four times more likely to have melancholy, anxiety, and difficulties working than those who do not.

16. Write down causes of following diseases:

(i) Diarrheal Diseases

(ii) Dysentery

(iii) Cholera

(iv) Crytosporidium

(v) Fluorosis

(vi) Hepatitis

(vii) Hookworm

(viii) Typhoid

Answer

17. What is the cause of acid rain? Explain. Write down the effects of acid rain and global warming.

Answer

Definition

Acid rain means the presence of excessive acids in rainwater, which are formed when the number of gaseous air pollutants like nitrogen dioxide and sulphur dioxide in the environment reacts with rainwater resulting in the formation sulphuric acid and nitric acid, which causes its decreasing pH value. When the concentration of rain has a pH value less than 5.5 is said to be acid rain. Acid rain is one of the consequences of air pollution.

Reason of formation of Acid Rain

1. The burning of fossil fuels produces oxides of sulphur and nitrogen (SO₂, NO, NO₂) into the atmosphere.

2. Rainwater converts SO₂ into H₂SO₄ and oxides of nitrogen i.e. NO and NO₂ into HNO₂ and HNO₃ respectively.

3. Rainwater is weakly acidic due to dissolved CO₂ of the air having a pH of 5.6 to 6.

4. Rainwater becomes more acidic and its pH reduced to 4 on dissolving air pollutants (i.e. acids).

5. Acid rain is formed on dissolving acidic air pollutant like sulphur dioxide and nitrogen oxides forming acids by rainwater.

Harmful Effects of Acid Rain

Acid rain causing harm to soil, animals, plants and aquatic life.

(i) Effects on Buildings and Monuments

Acid rain attacks and eats away the calcium carbonate present in the marble and limestone of many buildings and monuments. Consequently, these structures are getting increasingly dull and degraded day by day.

(ii) Effects on Aquatic Life

Acid rain on soil and rocks leaches heavy metals (AI, Hg, Pb, Cr, etc.) and discharges them into rivers and lakes. Humans consumes this water as a source of drinking water. These metals accumulate in human body to a toxic level.

On the other hand, the aquatic life in lakes, suffers because of the high concentration of these metals. Especially, the high concentration of aluminum ions clogs the fish gills. It causes suffocation and ultimately death of fish.

3. Effects on Trees and Plants

Acid rain directly damages the trees and plant leaves, limiting their growth. Plants development may hampered depending on the severity of the damage. Plants’ capacity to withstand cold or illnesses deteriorates, and they eventually perish.

4. Effect on Soil

Acid rain increases the acidity of the soil. Many crops and plants cannot grow properly in such acidic soil. It also increases the levels of toxic metals in the soil, which damage the plants. the acidity of the soil, even affects old trees. Their growth is retarded becoming dry and die.

What are primary and secondary air pollutants? Or Give difference between primary and secondary air pollutants. Identify as primary or secondary air pollutant SO₂, CH₄, HNO₃, NH₃, H₂SO4 and O₃

Answer

Primary Pollutants Vs Secondary Pollutants

Primary pollutants are the waste or exhaust products driven out because of the combustion of fossil fuels and organic materials. These are the oxides of sulphur (CO₂, SO₃), oxides of carbon (CO, CO₂), oxides of Nitrogen (especially nitric oxide NO and nitrogen dioxide, NO₂), hydrocarbons or greenhouse gases like CH₄, ammonia (NH₃) and fluorine compounds (CFCs)

Secondary pollutants are produced from various reaction of Primary pollutants together through a variety of processes. They include Sulphuric acid, nitric acid, carbonic acid, hydrofluoric acid, ozone and peroxy acetyl nitrate (PAN, CH₃–CO–O–O–NO₂).

18. Describe the composition of water. Write degree of Hardness of water on the basis of Dissolved Ca Ions (mg/L)

Answer

Rain water is considered as purest form of water. Drinking water contains ions like Na⁺, K⁺, Mg²⁺, Cl⁻ etc. necessary for our body.

Structure of Water

Water is simple covalent molecule comprising of one O atom bonded to two H atoms through single covalent bonds. Water is a polar molecule due to difference in electronegativity between H and O.

Due to higher electronegativity of the oxygen atom, the O–H bonds of water is highly polar in nature. The oxygen atoms attracts the shared electron pair of the covalent bonds towards itself to a greater extent than the H atoms acquiring a partial negative charge (δ−) while the both H atoms acquire a partial positive charge (δ+) thereby making the bond polar forming a dipole.

Degree of Hardness of water on the Basis of Dissolved Ca Ions (mg/L)

Soft water ………………….. 0 to 16.1 mg/L

Slightly hard water ……….. 16.1 to 60 mg/L

Moderate hard water ……. 61 to 120 mg/L

Hard water ………………. 121 to 180 mg/L

Very hard water …………. More than 180 mg/L

19. List down the applications of conductometry?

Answer

Applications

1. Degree of dissociation constant can be determined.

2. Solubility of a sparingly soluble can be determined.

3. Rate constant of a reaction can be studied.

4. End point of titration can be determined.

20. What is error? Write down causes of errors with their %. Write down brief note systematic and random errors with two examples each.

Describe fractional distillation of petroleum with its 5 fractions.

Answer

Petroleum is a naturally occurring dark brownish or greenish black coloured thick viscous liquid with bad smell found in underground deposits in various parts of earth at different depths comprising of a complex mixture of gaseous, liquid and solid hydrocarbons (ranging C1 to C40) like alkanes, alkenes, cycloalkanes, aromatic hydrocarbons together with the varying but small quantities of inorganic compounds of nitrogen, oxygen, and sulphur and earthy particles.

Separation of Petroleum Fractions by fractional distillation

The various components of petroleum is separated into fractions by fractional distillation (separation of fractions or components depending upon their boiling point ranges). More than 500 compounds have been formed in petroleum distillate boiling below 200°C. Each fraction is not a single compound, rather each of it consists of different organic compounds.

21. A solution of HCl has pH of 2.3. Calculate its pOH and [H+]?

OR Find pH, pOH, [OH−] and [H+] of 2.46 × 10−9 M KOH solution.

🚨 ⚡ Class 10 Exam 2026 Key MCQs: Master These Key MCQs for a Perfect Score! 🧑‍🏫💯" 🚀 Boost Your Score! 🎯

🎨 💥 Textbook MCQs on Chemical Equilibrium – Must Know Questions for Exams!

1. Which one of the following statements is FALSE about dynamic equilibrium?

🟩 A. Concentration of reactant and products are not changed

🟪 B. It takes place in a closed container

🟨 C. Rate of forward reaction equals rate of reverse reaction

🟦 D. Equilibrium cannot be disturbed by any external stress✔️

2. When the magnitude of Kc is small, it indicates:

🟩 A. Reaction mixture contains most of the reactant✔️

🟪 B. Reaction mixture contains most of the product

🟨 C. Nearly equal amounts of reactant and product

🟦 D. Reaction goes to completion

3. Qc can be defined as:

🟩 A. Ratio of product and reactant

🟪 B. Ratio of molar concentration of product and reactant at specific time✔️

🟨 C. Ratio of concentration of product and molar volume of reactant

🟦 D. Ratio of concentrations raised to coefficients

4. For the reaction

4NH₃(g) + 5O₂(g) ⇌ 4NO(g) + 6H₂O(g)

Which expression represents Kc?

🟩 A. [NO]⁴ [H₂O]⁶ / [NH₃]⁴ [O₂]⁵✔️

🟪 B. [NH₃]⁴ [O₂]⁵ / [NO]⁴ [H₂O]⁶

🟨 C. [NO][H₂O]/[NH₃][O₂]

🟦 D. [Products]/[Reactants] without exponents

5. For which system does Kc have units of concentration?

🟩 A. N₂(g) + 3H₂(g) ⇌ 2NH₃(g) ✔️

🟪 B. N₂(g) + O₂(g) ⇌ 2NO(g)

🟨 C. H₂(g) + I₂(g) ⇌ 2HI(g)

🟦 D. CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(g)

6. A reaction that does not go to completion is reversible. It is represented by:

🟩 A. Double straight line

🟪 B. Single arrow

🟨 C. Double arrow✔️(⇌ style representation)

🟦 D. Dotted lines

7. The unit of Kc for the reaction

N₂(g) + O₂(g) ⇌ 2NO(g)

🟩 A. mol dm⁻³

🟪 B. mol⁻² dm⁶✔️

🟨 C. mol⁻¹ dm³

🟦 D. No unit

8. The system is stable in equilibrium when:

🟩 A. Qc = Kc✔️

🟪 B. Qc > Kc

🟨 C. Qc < Kc

🟦 D. None

9. The value of Kc increases when:

🟩 A. [Reactant] = [Product]

🟪 B. Product concentration is more✔️

🟨 C. More reactant is present

🟦 D. Less product is present

10. Which of the following represent backward reaction?

🟩 A. (i) and (ii)

🟪 B. (ii) only✔️

🟨 C. (i) only

🟦 D. (iii) only

✅ Answer Key with Short Reasons

1️⃣ D — External stress (temperature, pressure, concentration) can disturb equilibrium.

2️⃣ A — Small Kc means reactants are favoured.

3️⃣B — Qc is ratio of concentrations at any moment, not equilibrium.

4️⃣A — Kc = products⁴⁺⁶ / reactants⁴⁺⁵ using coefficients as powers.

5️⃣A — Δn ≠ 0 gives units; here Δn = 2 − 4 = −2.

6️⃣ C — Reversible reactions use double arrows (⇌ / dotted).

7️⃣ B — Units depend on Δn (change in moles of gas).

8️⃣ A — A system is at equilibrium when Qc equals Kc.

9️⃣ B — Higher product concentration → larger Kc value.

🔟 B — Statement (ii) alone shows backward reaction.

🎨 💥 Textbook MCQs on Acids, Bases & Salts – Must Know Questions for Exams!

1. Corrosive effect on skin is caused by:

🟩 A. Acid

🟪 B. Base

🟨 C. Salt

🟦 D. Both a and b✔️

2. Preservatives are used to preserve:

🟩 A. Acid

🟪 B. Base

🟨 C. Food✔️

🟦 D. Water

3. Which of the following is NOT an Arrhenius acid?

🟩 A. HCl

🟪 B. CO₂✔️

🟨 C. HNO₃

🟦 D. H₂SO₄

4. NH₃ can be a base according to:

🟩 A. Arrhenius theory

🟪 B. Bronsted–Lowry theory

🟨 C. Lewis theory

🟦 D. Both b and c✔️

5. Which of the following is a Lewis base?

🟩 A. HNO₃

🟪 B. CN⁻✔️

🟨 C. HCl

🟦 D. AlCl₃

6. A substance that donates a pair of electrons to form a coordinate covalent bond:

🟩 A. Bronsted–Lowry base

🟪 B. Bronsted–Lowry acid

🟨 C. Lewis acid

🟦 D. Lewis base✔️

7. If pH value is greater than 7, the solution is:

🟩 A. Acidic

🟪 B. Basic✔️

🟨 C. Amphoteric

🟦 D. Neutral

8. Salt among the following is:

🟩 A. HCl

🟪 B. KCl✔️

🟨 C. HNO₃

🟦 D. H₂SO₄

9. Substances that react with both acids and bases are called:

🟩 A. Amphoteric substances✔️

🟪 B. Conjugate acids

🟨 C. Conjugate bases

🟦 D. Buffers

10. The reaction of an acid and a base to form salt and water is called:

🟩 A. Hydration

🟪 B. Neutralization✔️

🟨 C. Hydrolysis

🟦 D. Both a and c

✅ Answer Key with Short Reasons

1️⃣ D — Both acids and bases can cause burns.

2️⃣C — Preservatives prevent spoilage of food.

3️⃣B — CO₂ does not produce H⁺ ions directly in water (not Arrhenius acid).

4️⃣D — NH₃ accepts a proton (Bronsted) and donates lone pair (Lewis).

5️⃣B — CN⁻ has lone pairs available → Lewis base.

6️⃣D — Lewis base donates an electron pair.

7️⃣B — pH > 7 means basic.

8️⃣B — KCl is a salt formed from KOH + HCl.

9️⃣ A — Amphoteric substances react with both acids and bases.

🔟B — Neutralization = acid + base → salt + water.

🎨 💥 Top Textbook MCQs on Organic Chemistry You Can’t Miss!

1. The branch of chemistry that deals with hydrocarbons and their derivatives is:

🟩 A. Organic chemistry✔️

🟪 B. Inorganic chemistry

🟨 C. Physical chemistry

🟦 D. Biochemistry

2. The general formula of alkanes is:

🟩 A. CₙH₂ₙ

🟪 B. CₙH₂ₙ₊₁

🟨 C. CₙH₂ₙ₊₂✔️

🟦 D. CₙH₂ₙ₋₂

3. Which of the following is an alcohol?

🟩 A. CH₃CHO

🟪 B. CH₃CH₂OCH₃

🟨 C. CH₃OH✔️

🟦 D. HCOOH

4. Which of the following is a saturated hydrocarbon?

🟩 A. CH₃CH=CH₂

🟪 B. CH₃CH₂CH₃ ✔️

🟨 C. CH₃C≡CH

🟦 D. CH₂=CH–C≡CH

5. The prefix “hept–” stands for how many carbon atoms?

🟩 A. 2

🟪 B. 5

🟨 C. 7✔️

🟦 D. 9

6. The functional group –COOH is characteristic of:

🟩 A. Alkynes

🟪 B. Carboxylic acids✔️

🟨 C. Phenols

🟦 D. Alcohols

7. Polyethene is:

🟩 A. Oil

🟪 B. Paper

🟨 C. Plastic✔️

🟦 D. Wood

8. Acetic acid is obtained from:

🟩 A. Banana

🟪 B. Dates

🟨 C. Garlic

🟦 D. Vinegar✔️

9. CH₃–CH₂– is a/an ______ radical.

🟩 A. Methyl

🟪 B. Ethyl✔️

🟨 C. n-propyl

🟦 D. iso-propyl

10. Alkenes:

🟩 A. Show same general formula as alkynes

🟪 B. Have carbon–carbon triple bond

🟨 C. Have carbon–carbon double bond✔️

🟦 D. Are saturated hydrocarbons

✅ Answer Key with Short Reasons

1️⃣A — Organic chemistry studies hydrocarbons and their derivatives.

2️⃣C — Alkanes follow the formula CₙH₂ₙ₊₂ (single bonds).

3️⃣C — CH₃OH contains –OH group → alcohol.

4️⃣B — Saturated hydrocarbons have only single bonds (alkanes).

5️⃣C — “Hept–” = 7 carbons (IUPAC prefix).

6️⃣B — –COOH is the functional group of carboxylic acids.

7️⃣C — Polyethene is a commonly used plastic.

8️⃣D — Vinegar contains acetic acid.

9️⃣B — CH₃–CH₂– is the ethyl radical.

🔟C — Alkenes contain a C=C double bond.

🎨 💥 Textbook-Based Biochemistry MCQs Every Student Must Know

1. Glucose is:

🟩 A. Vitamin

🟪 B. Protein

🟨 C. Carbohydrate✔️

🟦 D. Lipid

2. The deficiency of vitamin D causes:

🟩 A. Beriberi

🟪 B. Rickets✔️

🟨 C. Scurvy

🟦 D. Haemorrhage

3. ______ encodes genetic information.

🟩 A. RNA

🟪 B. DNA✔️

🟨 C. Progesterone

🟦 D. Cholesterol

4. Carbohydrates containing an aldehyde group are called:

🟩 A. Saccharides

🟪 B. Ketoses

🟨 C. Pentose

🟦 D. Aldoses✔️

5. Amino acids are the building blocks of:

🟩 A. Nucleic acids

🟪 B. Proteins✔️

🟨 C. Vitamins

🟦 D. Lipids

6. Which one of the following is a polysaccharide?

🟩 A. Fructose

🟪 B. Maltose

🟨 C. Starch✔️

🟦 D. None

7. Lactose is:

🟩 A. Grape sugar

🟪 B. Honey sugar

🟨 C. Milk sugar✔️

🟦 D. Cane sugar

8. Cotton contains ___ cellulose.

🟩 A. 30%

🟪 B. 65%

🟨 C. 85%

🟦 D. 95%✔️

9. What is true about a peptide?

🟩 A. It is a protein

🟪 B. It is an anhydride of carboxylic acids

🟨 C. It is an anhydride of an amine

🟦 D. It is a polyamide✔️

10. Fats are solids at:

🟩 A. Ordinary room temperature✔️

🟪 B. High temperature

🟨 C. Above 50°C

🟦 D. None of them

✅ Answer Key with Short Reasons

1️⃣C — Glucose is a simple carbohydrate (monosaccharide).

2️⃣B — Vitamin D deficiency leads to weak bones → rickets.

3️⃣B — DNA stores and carries genetic information.

4️⃣D — Aldoses are sugars containing an aldehyde group.

5️⃣B — Proteins are polymers of amino acids.

6️⃣C — Starch is a polysaccharide (many glucose units).

7️⃣C — Lactose is milk sugar (glucose + galactose).

8️⃣D — Cotton is made of ~95% cellulose.

9️⃣D — Peptides are chains of amino acids linked by amide (peptide) bonds.

🔟A — Fats remain solid at ordinary room temperature.

🎨 💥 Textbook-Based Environmental Chemistry (The Atmosphere) MCQs Every Student Must Know 🌍✨

1. Second highest layer of Earth’s atmosphere is:

🟩 A. Stratosphere

🟪 B. Mesosphere✔️

🟨 C. Troposphere

🟦 D. Thermosphere

2. Aeroplanes fly in:

🟩 A. Troposphere✔️

🟪 B. Stratosphere

🟨 C. Mesosphere

🟦 D. Thermosphere

3. The altitude of the stratosphere is:

🟩 A. 40–45 km

🟪 B. 50–55 km✔️

🟨 C. 60–65 km

🟦 D. 70–75 km

4. The layer that separates the stratosphere and troposphere is:

🟩 A. Tropopause✔️

🟪 B. Mesopause

🟨 C. Thermopause

🟦 D. Stratopause

5. Ozone layer is part of:

🟩 A. Mesosphere

🟪 B. Stratosphere✔️

🟨 C. Thermosphere

🟦 D. Troposphere

6. Which is NOT a greenhouse gas?

🟩 A. Carbon dioxide

🟪 B. Methane

🟨 C. Nitrous oxide

🟦 D. Oxygen✔️

7. Second most abundant constituent of dry air after nitrogen is:

🟩 A. Nitrogen

🟪 B. Oxygen✔️

🟨 C. Carbon dioxide

🟦 D. Helium

8. Ozone is mainly found in the ______ layer:

🟩 A. Troposphere

🟪 B. Mesosphere

🟨 C. Stratosphere✔️

🟦 D. Exosphere

9. Which of the following is a reason for global warming?

🟩 A. Presence of sulphite

🟪 B. Rise in CO₂ concentration✔️

🟨 C. Oxides of nitrogen

🟦 D. Formation of ozone

10. Atmospheric pressure decreases with:

🟩 A. Increase in longitude

🟪 B. Decrease in altitude

🟨 C. Increase in altitude✔️

🟦 D. Increase in latitude

✅ Answer Key with Short Reasons

1️⃣B — Mesosphere lies above the stratosphere; it is the second highest layer.

2️⃣A — Aircraft fly mainly in the troposphere.

3️⃣B — Stratosphere extends roughly between 50–55 km.

4️⃣A — Tropopause separates troposphere and stratosphere.

5️⃣B — The ozone layer lies in lower stratosphere.

6️⃣D — Oxygen is not a greenhouse gas.

7️⃣B — Oxygen makes up ~21% of dry air after nitrogen.

8️⃣C — Most ozone is concentrated in the stratosphere.

9️⃣B — Higher CO₂ concentration enhances the greenhouse effect.

🔟C — Air pressure decreases as altitude increases.

🎨 💥 Textbook-Based Environmental Chemistry Part II (Water)MCQs Every Student Must Know 🌍💧

1. Which of the following water-borne diseases is of viral origin?

🟩 A. Typhoid fever

🟪 B. Polio✔️

🟨 C. Dysentery

🟦 D. Diarrhea

2. How much percentage of the Earth’s surface is covered with water?

🟩 A. 70%✔️

🟪 B. 60%

🟨 C. 90%

🟦 D. 75%

3. Which type of bond is formed between H₂O molecules?

🟩 A. Hydrogen bond✔️

🟪 B. Ionic bond

🟨 C. Covalent bond

🟦 D. All of these

4. Permanent hardness of water is due to the presence of:

🟩 A. MgSO₄✔️

🟪 B. Mg(HCO₃)₂

🟨 C. Ca(HCO₃)₂

🟦 D. All of these

5. How much fresh water is present in rivers and lakes?

🟩 A. 0.3%

🟪 B. 3%✔️

🟨 C. 0.2%

🟦 D. 2%

6. The taste of pure water is:

🟩 A. Sour

🟪 B. Bitter

🟨 C. Sweet

🟦 D. Tasteless✔️

7. Which of the following is helpful in removing permanent hardness?

🟩 A. Na₂CO₃✔️

🟪 B. Ca(OH)₂

🟨 C. CaCO₃

🟦 D. Na₂SO₄

8. Which salts are dissolved in water to make temporary hard water?

🟩 A. CaSO₄ and CaCl₂

🟪 B. KNO₃ and KOH

🟨 C. CaCO₃ and Ca(OH)₂

🟦 D. Ca(HCO₃)₂ and Mg(HCO₃)₂✔️

9. Water is a:

🟩 A. Polar solvent✔️

🟪 B. Non-polar solvent

🟨 C. Amphipathic solvent

🟦 D. Non-polar charged solvent

✅ Answer Key with Short Reasons

1️⃣B — Polio virus spreads through contaminated water.

2️⃣A — About 70% of Earth’s surface is covered with water.

3️⃣A — Hydrogen bonds form between water molecules.

4️⃣A — Permanent hardness is caused by sulphates (MgSO₄, CaSO₄).

5️⃣B — Freshwater in rivers and lakes is about 3%.

6️⃣D — Pure water is tasteless.

7️⃣A — Sodium carbonate removes permanent hardness by precipitation.

8️⃣D — Temporary hardness is due to bicarbonates of Ca and Mg.

9️⃣A — Water has polar O–H bonds → overall polar molecule.

🎨 💥 Textbook-Based Analytical Chemistry (Chapter 7)MCQs Every Student Must Know 🔬📊

1. Analytical chemistry deals with instruments and methods to ______, identify and quantify matter.

🟩 A. Mix

🟪 B. Separate✔️

🟨 C. Differentiate

🟦 D. Manipulate

2. The sample may be solid, liquid, gas or a ______ in qualitative analysis.

🟩 A. Mixture✔️

🟪 B. Compound

🟨 C. Substance

🟦 D. None

3. Analysis dealing with identification of functional groups in compounds is:

🟩 A. Physical qualitative analysis

🟪 B. Analytical qualitative analysis

🟨 C. Organic qualitative analysis✔️

🟦 D. Inorganic qualitative analysis

4. Flame test of copper halide shows bluish-green colour indicating presence of:

🟩 A. Halogen

🟪 B. Hydrogen

🟨 C. Copper✔️

🟦 D. b and c

5. The physical methods used to measure physical properties are called:

🟩 A. Combustion analysis method

🟪 B. Atomic emission spectroscopy method✔️

🟨 C. Volumetric analysis method

🟦 D. Gravimetric analysis method

6. The error caused by improper functioning of an instrument is:

🟩 A. Determinant error

🟪 B. Indeterminant error

🟨 C. Systematic error

🟦 D. Both a & c✔️

7. Agreement between measured value and true accepted value is:

🟩 A. Error

🟪 B. Accuracy✔️

🟨 C. Precision

🟦 D. All of these

8. Spectroscopy is the interaction of light with:

🟩 A. Liquid

🟪 B. Solid

🟨 C. Gas

🟦 D. Matter✔️

9. Gas is the mobile phase in:

🟩 A. Liquid chromatography

🟪 B. Solid chromatography

🟨 C. Gas chromatography✔️

🟦 D. None of these

10. Used to assess concentration or amount of an atomic/molecular/ionic substance:

🟩 A. Chromatography

🟪 B. Spectroscopy✔️

🟨 C. Conductometry

🟦 D. Potentiometry

✅ Answer Key with Short Reasons

1️⃣B — Analytical chemistry separates, identifies, quantifies matter.

2️⃣A — Samples can be mixtures in qualitative analysis.

3️⃣C — Functional group detection belongs to organic qualitative analysis.

4️⃣C — Copper salts show a characteristic bluish-green flame.

5️⃣B — Atomic emission spectroscopy measures physical properties of atoms.

6️⃣D — Instrument malfunction causes systematic/determinate errors.

7️⃣B — Accuracy = closeness to true value.

8️⃣D — Spectroscopy studies how light interacts with all forms of matter.

9️⃣C — Gas chromatography uses gas as mobile phase.

🔟B — Spectroscopy determines concentration using light–matter interaction.

🎨 💥 Textbook-Based Chemical Industries (Chapter 8)MCQs Every Student Must Know 🏭🧪

1. Soap is the term for salts of a:

🟩 A. Carboxylic group

🟪 B. Citric acid

🟨 C. Sulphuric acid

🟦 D. Fatty acid✔️

2. Surfactants reduce the ______ of water.

🟩 A. Viscosity

🟪 B. Surface tension✔️

🟨 C. Boiling point

🟦 D. Melting point

3. The carboxylate end of a soap molecule attracted to water is called:

🟩 A. Hydrophobic end

🟪 B. End point

🟨 C. Hydrophilic end✔️

🟦 D. None of them

4. The use of potassium hydroxide produces a:

🟩 A. Hard soap

🟪 B. Soft soap✔️

🟨 C. Moderate soap

🟦 D. All of these

5. Citric acid is used in cold drinks for:

🟩 A. Sweet taste

🟪 B. Bitter taste

🟨 C. Sour taste✔️

🟦 D. Salty taste

6. The centrifuge machine is used for separation of:

🟩 A. Juice

🟪 B. pH

🟨 C. Mud

🟦 D. Crystal✔️

7. Abrasives are:

🟩 A. Water-soluble minerals

🟪 B. Water-insoluble minerals✔️

🟨 C. Water semi-soluble minerals

🟦 D. Water-absorbing minerals

8. Harvesting is the most important step of:

🟩 A. Preparation of soap

🟪 B. Preparation of cold drinks

🟨 C. Preparation of sugar✔️

🟦 D. Preparation of medicines

9. Which of the following is used as jet fuel?

🟩 A. Kerosene oil✔️

🟪 B. Diesel oil

🟨 C. Fuel oil

🟦 D. Petrol

10. Which one of the following is NOT a fraction of crude oil?

🟩 A. Paraffin wax

🟪 B. Ammonia

🟨 C. Fuel oil

🟦 D. Petroleum coke✔️

✅ Answer Key with Short Reasons

1️⃣ D Soaps are sodium/potassium salts of fatty acids.

2️⃣ B Surfactants reduce surface tension, helping cleaning.

3️⃣ C The polar ionic end is hydrophilic (water-loving).

4️⃣ B KOH makes soft soap, NaOH makes hard soap.

5️⃣ C Citric acid provides sour taste in drinks.

6️⃣ D Centrifuge separates crystals by spinning.

7️⃣ B Abrasives are hard, insoluble minerals (e.g., silica).

8️⃣ C Sugar industry requires harvesting sugarcane.

9️⃣A Jet fuel is based on kerosene.

🔟 D Petroleum coke is a residual solid, not a crude fraction.

📝🔥 Unlock Success: Most Important Class 10 MCQs for the 2026 Exam! 🚀💡

1. Consider the reaction:

4NO(g) + 6H₂O(g) ⇌ 4NH₃(g) + 5O₂(g)

Expression for equilibrium constant Kc:

🟩 A. [NH₃]⁴ [O₂]⁵ / [NO]⁴ [H₂O]⁶ ✔️

🟪 B. [NO]⁴ [H₂O]⁶ / [NH₃]⁴ [O₂]⁵

🟨 C. [NH₃][O₂] / [NO][H₂O]

🟦 D. [NO][H₂O] / [NH₃][O₂]

2. For which system does Kc have units of concentration?

🟩 A. ✔️ N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

🟪 B. N₂(g) + O₂(g) ⇌ 2NO(g)

🟨 C. H₂(g) + I₂(g) ⇌ 2HI(g)

🟦 D. CO₂(g) + H₂(g) ⇌ CO(g) + H₂O(g)

3. Which of the following is NOT an Arrhenius acid?

🟩 A. HCl

🟪 B. ✔️ SO₂

🟨 C. HNO₃

🟦 D. H₂SO₄

4. Substances that react with both acids and bases are called:

🟩 A. ✔️ Amphoteric substances

🟪 B. Conjugate acids

🟨 C. Conjugate base

🟦 D. Buffers

5. Which of the following is a saturated hydrocarbon?

🟩 A. CH₃CH=CH₂

🟪 B. ✔️ CH₃CH₂CH₂CH₃

🟨 C. CH₃C≡CH

🟦 D. CH₂=CH–C≡CH

6. CH₃–CH₂–CH₂– is … radical:

🟩 A. Methyl

🟪 B. Ethyl

🟨 C. ✔️ n-Propyl

🟦 D. iso-Propyl

7. Surfactants reduce the ______ of water.

🟩 A. Viscosity

🟪 B. ✔️ Surface tension

🟨 C. Boiling point

🟦 D. Melting point

8. The carboxylate end of a soap molecule attracted to water is called:

🟩 A. Hydrophobic end

🟪 B. End point

🟨 C. ✔️ Hydrophilic end

🟦 D. None of them

9. Lactose is:

🟩 A. Grape sugar

🟪 B. Honey sugar

🟨 C. ✔️ Milk sugar

🟦 D. Cane sugar

10. The altitude of stratosphere is:

🟩 A. 40 to 45 km

🟪 B. ✔️ 50 to 55 km

🟨 C. 60 to 65 km

🟦 D. 70 to 75 km

11. Layer of atmosphere which separates stratosphere and troposphere is known as:

🟩 A. ✔️ Tropopause

🟪 B. Mesopause

🟨 C. Thermopause

🟦 D. Stratopause

12. Which is NOT part of greenhouse gases?

🟩 A. Carbon dioxide

🟪 B. Methane

🟨 C. Nitrous oxide (N₂O)

🟦 D. ✔️ Oxygen (O₂)

13. It is used for surfacing roads:

🟩 A. Naphtha

🟪 B. Paraffin

🟨 C. Coal

🟦 D. ✔️ Bitumen

14. The general formula of an alkyl radical is:

🟩 A. CₙH₂ₙ₊₂

🟪 B. CₙH₂ₙ₋₂

🟨 C. ✔️ CₙH₂ₙ₊₁

🟦 D. CₙH₂ₙ

15. Infrared radiation generated by Earth’s surface is absorbed in air by higher concentration of:

🟩 A. CH₄

🟪 B. O₃

🟨 C. ✔️ CO₂

🟦 D. N₂O

16. The permanent hardness of water is due to presence of:

🟩 A. ✔️ MgSO₄

🟪 B. Mg(HCO₃)₂

🟨 C. Ca(HCO₃)₂

🟦 D. All of these

17. Flame test of copper halide with bluish-green color identifies the presence of:

🟩 A. Halogen

🟪 B. Hydrogen

🟨 C. ✔️ Copper (Cu²⁺)

🟦 D. b and c

18. Spectroscopy is the interaction of light with:

🟩 A. Liquid

🟪 B. Solid

🟨 C. Gas

🟦 D. ✔️ Matter

19. Which type of bond is formed between H₂O molecules?

🟩 A. ✔️ Hydrogen bond

🟪 B. Ionic bond

🟨 C. Covalent bond

🟦 D. All of these

20. Soaps is the term for a salt of a:

🟩 A. Carboxylic acid

🟪 B. Citric acid

🟨 C. Sulphuric acid

🟦 D. ✔️ Fatty acid

21. The use of potassium hydroxide produces a:

🟩 A. Hard soap

🟪 B. ✔️ Soft soap

🟨 C. Moderate soap

🟦 D. All of these

22. Citric acid is used in preparation of cold drinks for:

🟩 A. Sweet taste

🟪 B. Bitter taste

🟨 C. ✔️ Sour taste

🟦 D. Salty taste

23. The value of Kc increases when:

🟩 A. [Reactant] = [Product]

🟪 B. [Product] is less

🟨 C. [Reactant] is less ✔️

🟦 D. [Product] is less

24. Which of the following represents backward reaction?

🟩 A. (i) and (ii)

🟪 B. ✔️ (ii) only

🟨 C. (i) only

🟦 D. (iii) only

25. If pH value is greater than 7, the solution is:

🟩 A. Acidic

🟪 B. ✔️ Basic

🟨 C. Amphotetic

🟦 D. Neutral

26. Polyethene is:

🟩 A. Oil

🟪 B. Paper

🟨 C. ✔️ Plastic

🟦 D. Wood

27. Fresh water present on the surface of Earth is:

🟩 A. 0.3%

🟪 B. ✔️ 3%

🟨 C. 0.2%

🟦 D. 2%

28. The gas is the mobile phase in:

🟩 A. Liquid chromatography

🟪 B. Solid chromatography

🟨 C. ✔️ Gas chromatography

🟦 D. None of these

29. Deficiency of which vitamin causes scurvy?

🟩 A. D

🟪 B. ✔️ C

🟨 C. B

🟦 D. A

30. Water covers around ………… % of Earth’s surface:

🟩 A. 50

🟪 B. 60

🟨 C. ✔️ 70

🟦 D. 80

31. Water is:

🟩 A. Acidic and polar

🟪 B. Neutral and non-polar

🟨 C. Acidic and non-polar

🟦 D. ✔️ Neutral and polar

32. Which of the following is a Lewis acid?

🟩 A. HCl

🟪 B. HNO₃

🟨 C. NH₃

🟦 D. ✔️ AlCl₃

33. Fructose is:

🟩 A. Fruit sugar

🟪 B. Honey sugar

🟨 C. Ketose sugar

🟦 D. ✔️ All of these

34. The functional group –CHO is used for:

🟩 A. Carboxylic acid

🟪 B. ✔️ Aldehyde

🟨 C. Ketone

🟦 D. Alcohol

35. Rickets is caused by deficiency of:

🟩 A. Vitamin A

🟪 B. ✔️ Vitamin D

🟨 C. Vitamin C

🟦 D. Vitamin E

36. The pH of 1.0 M HCl solution is:

🟩 A. ✔️ 0

🟪 B. 1

🟨 C. 2

🟦 D. 7

37. Arrhenius theory is applicable in:

🟩 A. ✔️ Aqueous solution

🟪 B. Non-aqueous solution

🟨 C. Both of them

🟦 D. Binary solution

38. The IUPAC name of iso-pentane is:

🟩 A. ✔️ 2,2-Dimethylbutane

🟪 B. 2-Methylpentane

🟨 C. 2,2-Dimethylpropane

🟦 D. 2-Methylbutane

39. Glycogen is an example of:

🟩 A. Monosaccharide

🟪 B. Oligosaccharide

🟨 C. Disaccharide

🟦 D. ✔️ Polysaccharide

40. End point of titration can be determined by:

🟩 A. HPLC

🟪 B. Potentiometry

🟨 C. Conductometry

🟦 D. ✔️ All of these

41. The name vitamin was coined by:

🟩 A. J. Wöhler

🟪 B. Watson and Crick

🟨 C. Hopkins

🟦 D. ✔️ Funk

42. Which of the following is NOT an example of neutral salt?

🟩 A. KCl

🟪 B. K₂SO₄

🟨 C. ✔️ K₂CO₃

🟦 D. KNO₃

43. The unit of Kc for reaction: Fe³⁺ + 4Cl⁻ → FeCl₄⁻

🟩 A. ✔️ mol⁻¹ dm³

🟪 B. mol⁻⁴ dm¹²

🟨 C. mol⁻² dm¹⁶

🟦 D. mol⁴ dm¹²

44. The pH of black coffee is:

🟩 A. 7.0

🟪 B. ✔️ 5.0

🟨 C. 13.0

🟦 D. 7.35

45. Deficiency of vitamin K leads to:

🟩 A. Scurvy

🟪 B. Haemolysis

🟨 C. ✔️ Hemorrhage

🟦 D. Rickets

46. Which of the following pair of compounds does not belong to the same homologous series?

🟩 A. C₂H₄ & C₃H₆

🟪 B. CH₄ & C₂H₆

🟨 C. C₂H₅OH & C₃H₇OH

🟦 D. ✔️ C₂H₂ & C₃H₈

47. Which of the following pair of compounds does not differ by –CH₂– group?

🟩 A. C₉H₂₀ & C₁₀H₂₂

🟪 B. C₂H₅ & C₃H₇

🟨 C. C₂H₅Cl & C₃H₇Cl

🟦 D. ✔️ C₂H₂ & C₂H₄

48. Which of the following is NOT used in the preparation of soft drinks?

🟩 A. Water

🟪 B. Sucrose

🟨 C. ✔️ Fatty acid

🟦 D. Citric acid

49. This is known as blood sugar:

🟩 A. Fructose

🟪 B. ✔️ Glucose

🟨 C. Lactose

🟦 D. Maltose

50. This one of the following is used as jet aircraft fuel?

🟩 A. Fuel oil

🟪 B. Diesel oil

🟨 C. ✔️ Kerosene oil

🟦 D. Petrol

51. The closeness between the measured value and the true value of an observation is called:

🟩 A. ✔️ Accuracy

🟪 B. Precision

🟨 C. Difference

🟦 D. Error

52. The ordinary IR region extends from …………… wavelength (µm):

🟩 A. ✔️ 2.5–15

🟪 B. 2.6–15

🟨 C. 2.7–15

🟦 D. 2.8–15

53. Atmospheric pressure decreases with the:

🟩 A. Increase in longitude

🟪 B. Decrease in altitude

🟨 C. ✔️ Increase in altitude

🟦 D. None

✅ Answer Key with Short Reasons

1 A Kc = [products]^coeff / [reactants]^coeff.

2 A Δn ≠ 0; Kc has units when moles of products ≠ reactants.

3 B SO₂ is not a proton donor, so not Arrhenius acid.

4 A Amphoteric substances react with both acids & bases.

5 B Saturated hydrocarbons contain only single C–C bonds.

6 C CH₃–CH₂–CH₂– = n-propyl radical.

7 B Surfactants lower water’s surface tension.

8 C Hydrophilic end is polar, interacts with water.

9 C Lactose = milk sugar (glucose + galactose).

10 B Stratosphere: 50–55 km above Earth’s surface.

11 A Tropopause separates troposphere & stratosphere.

12 D O₂ is not a greenhouse gas.

13 D Bitumen is used in road surfacing.

14 C Alkyl radical: CₙH₂ₙ₊₁.

15 C CO₂ absorbs IR radiation, contributing to greenhouse effect.

16 A Permanent hardness is due to Mg²⁺/Ca²⁺ salts (e.g., MgSO₄).

17 C Bluish-green flame confirms presence of Cu²⁺.

18 D Spectroscopy studies light-matter interactions.

19 A H-bonds form between H₂O molecules.

20 D Soaps are salts of fatty acids.

21 B KOH produces soft soap due to solubility of potassium salts.

22 C Citric acid gives sour taste in beverages.

23 C Kc increases when reactant concentration is less.

24 B Backward reaction is represented by the reverse arrow (ii).

25 B pH > 7 indicates basic solution.

26 C Polyethene is a plastic polymer.

27 B Only ~3% of water on Earth is fresh water.

28 C In gas chromatography, gas acts as the mobile phase.

29 B Vitamin C deficiency causes scurvy.

30 C ~70% of Earth's surface is covered with water.

31 D Water is neutral (pH ~7) and polar due to H–O–H structure.

32 D Lewis acid accepts an electron pair; AlCl₃ is electron-deficient.

33 D Fructose is found in fruits, honey, and is a ketose sugar.

34 B –CHO is the functional group for aldehydes.

35 B Lack of Vitamin D causes rickets (soft bones).

36 A pH = −log[H⁺] = 0 for 1 M HCl.

37 A Arrhenius theory applies to aqueous solutions only.

38 A Iso-pentane’s IUPAC name is 2,2-dimethylbutane.

39 D Glycogen is a polysaccharide (many glucose units).

40 C End point can be determined by multiple methods: HPLC, potentiometry, or conductometry

41 D Funk coined the term “vitamine” for essential amines.

42 C K₂CO₃ is basic, not neutral.

43 A For Fe³⁺ + 4Cl⁻ → FeCl₄⁻, Kc unit = mol⁻¹ dm³.

44 B Black coffee is acidic, pH ~5.

45 C Vitamin K deficiency causes hemorrhage (blood clotting issues).

46 D C₂H₂ (alkyne) & C₃H₈ (alkane) are different homologous series.

47 D C₂H₂ & C₂H₄ differ by a double bond, not –CH₂– group.

48 C Fatty acids are not used in soft drinks.

49 B Glucose is blood sugar.

50 C Kerosene oil is used as jet fuel.

51 A Accuracy measures closeness to the true value.

52 A Ordinary IR region is 2.5–15 µm.

53 C Atmospheric pressure decreases with increasing altitude.

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Guess Paper 2027 X-Chemistry Karachi Board National Comprehensive Targeted with Complete Solution | Class 10 Chemistry Guess Paper

✏️ X-CHEMISTRY Guess Paper 2027 with solutionDr Inam Ul Haq Jazbi ✏️

✏️ Section-B (Short-Answer Questions) 8 Questions 3 marks each (24) ✏️

✏️ Section-C (Long-Answer Questions) 4 Questions 6 marks each (24) ✏️

✏️ Numericals ✏️

✏️ X-CHEMISTRY Interactive MCQs (Click MCQ to reveal answer and reasonDr Inam Ul Haq Jazbi ✏️

✏️ Smart Answers of Section-B (Short-Answer Questions) ✏️

1️⃣ Define any three of the following:

Answer

🧪 Acids, Bases & Titration

🌱 Organic Chemistry Basics

🍬 Carbohydrates & Biomolecules

🧠 Biochemistry & Biological Molecules

🌍 Environmental Chemistry

📊 Analytical Chemistry & Measurement

🧪 Chromatography & Instrumental Methods

2️⃣

Answer

(i) 🌿 Saturated vs Unsaturated Hydrocarbons

(ii) 🧈 Fat vs Oil

(iii) 💊 Fat-soluble vs Water-soluble Vitamins

(iv) 🔄 Dextrorotatory vs Levorotatory Sugars

(v) 📊 Quantitative vs Qualitative Analysis

(vi) 🔁 Reversible vs Irreversible Reactions

(vii) 🧪 Classical vs Instrumental Methods ⚙️

(viii) 🌍 Troposphere vs Stratosphere

3️⃣

Answer

OR

Answer

4️⃣

Answer

5️⃣

Answer

Answer

6️⃣

Answer

Answer

Answer

7️⃣

Answer

Answer

8️⃣

Answer

Answer

Answer

Answer

9️⃣

Answer

Answer

🔟

Answer

Answer

Answer

Answer

1️⃣1️⃣

Answer

1️⃣2️⃣

Answer

Answer

1️⃣3️⃣

Answer

Answer

1️⃣4️⃣

Answer

Answer

1️⃣5️⃣

Answer

Answer

1️⃣6️⃣

Answer

Answer

1️⃣7️⃣

Answer

Answer

1️⃣8️⃣

Answer

1️⃣9️⃣

Answer

Answer

✏️ X-CHEMISTRY Guess Paper 2027 with solution
Dr Inam Ul Haq Jazbi ✏️

✏️ X-CHEMISTRY Interactive MCQs (Click MCQ to reveal answer and reason
Dr Inam Ul Haq Jazbi ✏️