🎉📚 Karachi Board Chemistry MCQs Past Papers 2025, 2024 & 2023 Class 11| 🔥 Download & Prepare for Success in Chemistry! 💡

👋 Welcome to Inamjazbi's Learn Chemistry! 🎓

Get ready to ace your Karachi Board exams with our MCQs past papers for 2025, 2024, and 2023. 💥

Download the Karachi Board Chemistry MCQs to help you prepare efficiently for your exams. 📝📖

Stay tuned for updated study materials, tips, and exam strategies to guide you through your chemistry learning journey. 🚀

Download & Prepare for Success in Chemistry! 

#Inamjazbi #LearnChemistry #KarachiBoard #KarachiBoardMCQs #ChemistryPastPapers #MCQs2025 #ChemistryExams #KarachiBoardExams #ChemistryPreparation #ExamTips #StudyWithInamjazbi #ChemistryMadeEasy

🌟 Ultimate Chemistry Challenge! 🌟
How well do you know chemistry? Let’s test your knowledge!
Check out these mind-bending questions below! 🔥

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2025 | 🔥 💡

1️⃣At 4°C the density of water is 1 g/cm³ then the mass of 2dm³ of water is
🟦 a) 18 g
🟩 b) 100 g
🟨 c) 1000 g
🟥 d) 2000 g

2️⃣Total number of atoms in one mole of methane (CH₄) is:
🟦 a) 6.02 × 10²³
🟩 b) 3.01 × 10²⁴
🟨 c) 1.81 × 10²³
🟥 d) 30.1 × 10²⁴

3️⃣ The colour with the longest wavelength is:
🟦 a) Red
🟩 b) Blue
🟨 c) Green
🟥 d) Orange

4️⃣ Magnetic quantum numbers for the last subshell having 3 electrons in phosphorus (₁₅P³¹) are:
🟦 a) -1, 0, +1
🟩 b) -1, 0, -1
🟨 c) -1, 0, +2
🟥 d) -1, 0, -2

5️⃣Maximum number of electrons in a subshell is:
🟦 a) 2l + 1
🟩 b) 2l ̵1
🟨 c) 2(2l + 1)
🟥 d) 2(2l ̵ 1)

6️⃣ The least polar molecule among the following is:
🟦 a) HF
🟩 b) HCl
🟨 c) HBr
🟥 d) HI

7️⃣The rate of diffusion of a gas is ½ of that of hydrogen, then its molecular mass is:
🟦 a) 8 amu
🟩 b) 10 amu
🟨 c) 25 amu
🟥 d) 50 amu

8️⃣ The pair of gases that do not obey Dalton’s law of partial pressure:
🟦 a) H₂ and O₂
🟩 b) NH₃ and HCl
🟨 c) N₂ and O₂
🟥 d) H₂ and He

9️⃣ The compound that does not contain hydrogen bonding is:
🟦 a) CH₄
🟩 b) H₂O
🟨 c) NH₃
🟥 d) HF

1️⃣0️⃣In crystalline structure, when length of axes and angles are unequal, then crystal system will be:
🟦 a) Cubic
🟩 b) Monoclinic
🟨 c) Orthorhombic
🟥 d) Triclinic

1️⃣1️⃣Kc = Kₚ, when Δn is equal to:
🟦 a) Zero
🟩 b) -1
🟨 c) +1
🟥 d) -2

1️⃣2️⃣ This pair of ions is not iso-electronic:
🟦 a) Na⁺ and Mg²⁺
🟩 b) Na⁺ and N³⁻
🟨 c) Na⁺ and S²⁻
🟥 d) Al³⁺ and Na⁺

1️⃣3️⃣ Quantum number values for 3p orbital are:
🟦 a) n = 2, l = 1
🟩 b) n = 3, l = 2
🟨 c) n = 3, l = 1
🟥 d) n = 3, l = 0

1️⃣4️⃣ Two different solids having the same crystal structure are called:
🟦 a) Allotropy
🟩 b) Polymorphous
🟨 c) Isotopes
🟥 d) Isomorphous

1️⃣5️⃣ A colloidal solution of a liquid into another liquid is called:
🟦 a) Emulsion
🟩 b) Foam
🟨 c) Gel
🟥 d) Sol

1️⃣6️⃣ This liquid shows maximum surface tension:
🟦 a) Water
🟩 b) Ethyl Alcohol
🟨 c) Mercury
🟥 d) Gasoline

1️⃣7️⃣A reaction is first order with respect to 'A' and second order with respect to 'B'. Then the rate expression is:
🟦 a) Rate = KA][B]²
🟩 b) Rate = K[A]²[B]
🟨 c) Rate = KA][B]
🟥 d) Rate = K[A]²[B]³

✅ Answer Key with Short Explanations of Karachi Board XI Chemistry MCQs Past Paper 2024✨

1️⃣ d) 2000 g — Mass = Density × Volume; 1 g/cm³ × 2000 cm³ = 2000 g.

2️⃣ b) 3.01 × 10²⁴ — One mole contains Avogadro's number of atoms (6.02 × 10²³). In CH₄, 1 mole contains 5 atoms (1 C + 4 H), so total = 3.01 × 10²⁴. Total atoms = mole × Avogadro’s number = 5 × 6.02×10²³ = 3.01 × 10²⁴ atoms per molecule

3️⃣ a) Red — Red has the longest wavelength in the visible spectrum.

4️⃣ a) -1, 0, +1 — For phosphorus, the last subshell (3p) can hold up to 3 electrons with quantum numbers -1, 0, and +1.

5️⃣ c) 2(2l + 1) — The maximum number of electrons in a subshell is given by this formula.

6️⃣ d) HI — HI is Least electronegativity difference → least polar because iodine is large and its electron cloud is more diffuse.

7️⃣ a) 8 amu — Using Graham's Law of Diffusion, the molecular mass of the gas is 8 amu when its diffusion rate is half that of hydrogen.

8️⃣ b) NH₃ and HCl — React chemically to form NH₄Cl, violating Dalton’s law

9️⃣ a) CH₄ — No hydrogen bonding due to lack of highly electronegative atoms bonded to H

1️⃣0️⃣ d) Triclinic — Triclinic crystal systems have all three axes of unequal length and none of the angles are 90°. It’s the most asymmetric and least symmetrical of all seven crystal systems.

1️⃣1️⃣ a) Zero — Kc = Kₚ when the change in moles of gas (Δn) is zero.

1️⃣2️⃣ d) Al³⁺ and Na⁺ — Al³⁺ and Na⁺ are not iso-electronic because they have different numbers of electrons.

1️⃣3️⃣ c) n = 3, l = 1 — For 3p orbital, principal quantum number is 3 and azimuthal quantum number for p is 1.

1️⃣4️⃣ d) Isomorphous — Two solids with the same crystal structure but different chemical composition are isomorphous.

1️⃣5️⃣ a) Emulsion — A colloid where both dispersed phase and dispersion medium are liquids (like milk).

1️⃣6️⃣ c) Mercury —has the highest surface tension due to strong metallic bonding.

1️⃣7️⃣ a) Rate = K[A][B]² — The rate expression is based on the order of reaction with respect to each reactant. Reaction order is sum of powers: 1 (A) + 2 (B) = 3rd order overall.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2024 | 🔥 💡

1️⃣ Significant figures in 0.0880 are:
🟦 a) 2
🟩 b) 3
🟨 c) 4
🟥 d) 5

2️⃣ Alpha rays consist of
🟦 a) Two protons and two electrons
🟩 b) Two protons and two neutrons
🟨 c) Two neutrons and two electrons
🟥 d) Two neutrons and one proton

3️⃣ The number of orbitals in fourth energy level is:
🟦 a) 4
🟩 b) 9
🟨 c) 16
🟥 d) 32

4️⃣ The number of sigma and pi bonds in C₂H₂ are:
🟦 a) 2 and 3
🟩 b) 2 and 2
🟨 c) 3 and 2
🟥 d) 3 and 3

5️⃣ This molecule has minimum bond angle:
🟦 a) CS₂
🟩 b) H₂O
🟨 c) NH₃
🟥 d) BF₃

6️⃣ The geometry of NH₄⁺, and SO₄²⁻ ions is:

🟦 a) Tetrahedral
🟩 b) Trigonal
🟨 c) Pyramidal
🟥 d) Square Planer

7️⃣These pairs do not obey Dalton's Law
🟦 a) He and H₂
🟩 b) H₂ and Ar
🟨 c) HCl and NH₃
🟥 d) He and NH₃

8️⃣ The vapour pressure of H₂O at 100 °C is:
🟦 a) 76 torr
🟩 b) 5 atms
🟨 c) 101325 Pascal
🟥 d) 12.5 psi

9️⃣  London dispersion force is stronger in:
🟦 a) F₂
🟩 b) Cl₂
🟨 c) Br₂
🟥 d) I₂

1️⃣0️⃣ Diamond is an example of:
🟦 a) Metallic Solid
🟩 b) Molecular Solid
🟨 c) Ionic Solid
🟥 d) Covalent Solid

1️⃣1️⃣ If a ≠b≠ c and α = γ = 90° but β≠90°, then the crystal structure is

🟦 a) Orthorhombic
🟩 b) Hexagonal
🟨 c) Monoclinic
🟥 d) Triclinic

1️⃣2️⃣If a catalyst is added in a chemical system at equilibrium, the value of Kc

🟦 a) will decrease
🟩 b) will become zero
🟨 c) will increase
🟥 d) will not be changed

1️⃣3️⃣ This oxide is amphoteric:

🟦 a) KO₂
🟩 b) CO₂
🟨 c) CaO
🟥 d) Al₂O₃

1️⃣4️⃣ If the rate law of reaction is R=K, its order of reaction is:
🟦 a) zero
🟩 b) first
🟨 c) Second
🟥 d) Third

1️⃣5️⃣  The oxidation numbers of N in NH₄NO₃ are:
🟦 a) -3, +5
🟩 b) -3, +3
🟨 c) -5, +5
🟥 d) -1, +1

1️⃣6️⃣ This compound gives acidic solution when dissolved in water:
🟦 a) NaCl
🟩 b) NH₄Cl
🟨 c) CH₃COONH₄
🟥 d) Na₂SO₄

1️⃣7️⃣ At pH=0, the universal indicator shows this colour:
🟦 a) Red
🟩 b) Orange
🟨 c) Yellow
🟥 d) Green

✨ Answers & Explanations of Karachi Board XI Chemistry MCQs Past Paper 2024✨

1️⃣ Answer: 🟩 b) 3
Reason: The significant figures in 0.0880 are 3 (8, 8, and the trailing zero counts because it's after a decimal point).

2️⃣ Answer: 🟩 b) Two protons and two neutrons
Reason: Alpha rays (α) consist of 2 protons and 2 neutrons, which is the same as a helium nucleus.

3️⃣ Answer: 🟨 c) 16
Reason: The 4th energy level has 16 orbitals (1s, 3p, 5d, 7f).

4️⃣ Answer: 🟩 b) 2 and 2
Reason: In C₂H₂, there are 2 sigma bonds and 2 pi bonds.

5️⃣ Answer: 🟩 b) H₂O
Reason: Water (H₂O) has a bent shape and a bond angle of about 104.5°, which is the smallest compared to the others.

6️⃣ Answer: 🟦 a) Tetrahedral
Reason: Both NH₄⁺ and SO₄²⁻ have tetrahedral geometries.

7️⃣ Answer: 🟩 b) H₂ and Ar
Reason: Dalton's Law assumes ideal gas behavior, and H₂ and Ar don't obey it under non-ideal conditions due to differences in molecular size.

8️⃣ Answer: 🟩 b) 5 atms
Reason: The vapor pressure of H₂O at 100°C is approximately 1 atm, but in some conditions (like closed containers), it can reach 5 atm.

9️⃣ Answer: 🟩 b) Cl₂
Reason: London dispersion forces increase with molecular size. I₂ has the largest size, so it's the strongest.

1️⃣0️⃣ Answer: 🟩 d) Covalent Solid
Reason: Diamond is a covalent solid, as it has a network of covalent bonds throughout.

1️⃣1️⃣  Answer: 🟦 a) Orthorhombic

Reason: Orthorhombic crystals have unequal lengths in three directions with all angles at 90° except β.

1️⃣2️⃣ Answer: 🟩 d) will not be changed
Reason: A catalyst speeds up the reaction but does not affect the equilibrium constant (Kc).

1️⃣3️⃣ Answer: 🟩 d) Al₂O₃
Reason: Aluminum oxide (Al₂O₃) is amphoteric, meaning it can react as both an acid and a base.

1️⃣4️⃣ Answer: 🟦 a) Zero
Reason: If the rate law is R = K, then the order is zero because there’s no concentration dependence.

1️⃣5️⃣ Answer: 🟩 a) -3, +5
Reason: The oxidation numbers of N in NH₄NO₃ are -3 in NH₄⁺ and +5 in NO₃⁻.

1️⃣6️⃣ Answer: 🟩 b) NH₄Cl
Reason: NH₄Cl dissociates to form NH₄⁺ (a weak acid) in solution, making the solution acidic.

1️⃣7️⃣ Answer: 🟦 a) Red

Reason: At pH = 0 (strongly acidic), the universal indicator turns red.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2023 | 🔥 💡

1️⃣. No. of atoms in 60g carbon will be:

🟥 (A) 3.0 × 10²³

🟩 (B) 3.01 × 10²⁴

🟦 (C) 6.02 × 10²³

🟨 (D) 6.02 × 10²⁴

2️⃣. Line spectra is used for the identification of an/a:

🟥 (A) Proton

🟩 (B) Electron

🟦 (C) Element

🟨 (D) Molecule

3️⃣. According to Hund's rule, the electronic configuration of carbon (C = 6) is:

🟥 (A) 1s², 2s², 2px¹, 2py¹

🟩 (B) 1s², 2s², 2px¹, 2py¹, 2pz¹

🟦 (C) 1s², 2s², 2px¹, 2py²

🟨 (D) 1s², 2s², 2px²

4️⃣. The bond order in N₂ molecule is:

🟥 (A) 0

🟩 (B) 1

🟦 (C) 2

🟨 (D) 3

5️⃣. This molecule has zero dipole moment:

🟥 (A) NH₃

🟩 (B) HCl

🟦 (C) H₂O

🟨 (D) CCl₄

6️⃣. Under similar conditions CH₄ gas diffuses faster than SO₂ gas:

🟥 (A) 1.5 times

🟩 (B) 2 times

🟦 (C) 4 times

🟨 (D) 16 times

7️⃣. It is an example of crystalline solid:

🟥 (A) Glass

🟩 (B) Rubber

🟦 (C) Table salt

🟨 (D) Plastic

8️⃣. This liquid has the highest surface tension:

🟥 (A) Water

🟩 (B) Mercury

🟦 (C) Ethanol

🟨 (D) Gasoline

9️⃣. When catalyst is added to a system, equilibrium Kc will be:

🟥 (A) Decreased

🟩 (B) Increased

🟦 (C) Unchanged

🟨 (D) Zero

1️⃣0️⃣. In equilibrium system; PCl₅ ⇌ PCl₃ + Cl₂; The relationship between Kp and Kc is:

🟥 (A) Kp > Kc

🟩 (B) Kc > Kp

🟦 (C) Kp = Kc

🟨 (D) Kp ≠ Kc

1️⃣1️⃣. This oxide is amphoteric in nature:

🟥 (A) K₂O

🟩 (B) CO₂

🟦 (C) CaO

🟨 (D) Al₂O₃

1️⃣2️⃣. In pure water, universal indicator acquires this colour:

🟥 (A) Red

🟩 (B) Green

🟦 (C) Blue

🟨 (D) Pink

1️⃣3️⃣. Rate constant of a chemical reaction is affected by:

🟥 (A) Reaction time

🟩 (B) Concentration of reactant

🟦 (C) Concentration of products

🟨 (D) Temperature

1️⃣4️⃣. The sum of mole fractions of all the components of a solution is equal to:

🟥 (A) 1

🟩 (B) 10

🟦 (C) 100

🟨 (D) 0

1️⃣5️⃣. Size of particles in a colloidal solution is:

🟥 (A) Less than 1nm

🟩 (B) Between 1nm & 1000nm

🟦 (C) Above 1000nm

🟨 (D) Zero

1️⃣6️⃣. In a thermochemical process, work is zero if this is kept constant:

🟥 (A) Temperature

🟩 (B) Volume

🟦 (C) Pressure

🟨 (D) Mass

1️⃣7️⃣. The outer body of a dry cell is made up of:

🟥 (A) Copper

🟩 (B) Zinc

🟦 (C) Lead

🟨 (D) Iron

✨ Answers & Explanations ✨

1️⃣. (C) 6.02 × 10²³

Reason: The number of atoms in 1 mole of any substance is Avogadro’s number, 6.02 × 10²³. For 60g of carbon (1 mole), the number of atoms is 6.02 × 10²³.

2️⃣. (C) Element

Reason: Line spectra are unique for each element and are used to identify specific elements based on their emission spectra.

3️⃣. (A) 1s², 2s², 2px¹, 2py¹

Reason: According to Hund’s rule, electrons fill degenerate orbitals singly before pairing. So, in carbon, electrons occupy 2px and 2py orbitals with one electron each.

4️⃣. (D) 3

Reason: The bond order in N₂ is 3, based on molecular orbital theory.

5️⃣. (D) CCl₄

Reason: CCl₄ is a tetrahedral molecule with symmetry, so the dipoles cancel out, resulting in zero dipole moment.

6️⃣. (C) 4 times

Reason: According to Graham’s law of diffusion, the rate of diffusion is inversely proportional to the square root of the molar mass. CH₄ has a lower molar mass than SO₂, so it diffuses 4 times faster.

7️⃣. (C) Table salt

Reason: Table salt is a crystalline solid with a regular arrangement of ions, unlike glass or rubber.

8️⃣. (A) Water

Reason: Water has a high surface tension due to hydrogen bonding between molecules.

9️⃣. (C) Unchanged

Reason: A catalyst speeds up the reaction but does not affect the position of equilibrium, so Kc remains unchanged.

1️⃣0️⃣. (C) Kp = Kc

Reason: For gases in equilibrium, Kp and Kc are related by the ideal gas law, but in this case, they are equal because there’s no change in the number of moles of gas on both sides of the reaction.

1️⃣1️⃣. (D) Al₂O₃

Reason: Al₂O₃ is amphoteric because it can react with both acids and bases.

1️⃣2️⃣. (B) Green

Reason: The universal indicator turns green in pure water, which has a neutral pH of 7.

1️⃣3️⃣. (D) Temperature

Reason: The rate constant (k) is affected by temperature according to the Arrhenius equation.

1️⃣4️⃣. (A) 1

Reason: The sum of the mole fractions of all components in a solution is always 1.

1️⃣5️⃣. (B) Between 1nm & 1000nm

Reason: Colloidal particles range in size from 1 nm to 1000 nm.

1️⃣6️⃣. (B) Volume

Reason: Work is zero if the volume is constant (isochoric process).

1️⃣7️⃣. (B) Zinc

Reason: The outer casing of a dry cell is typically made of zinc, which serves as the anode in the cell.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2022 | 🔥 💡

1️⃣. 3.01 x 10²³ molecules of oxygen gas at STP occupy a volume of
🟥 (A) 22.4 dm³
🟩 (B) 224 dm³
🟦 (C) 11.2 dm³
🟨 (D) 2.24 dm³

2️⃣. 602.10 has significant figures
🟥 (A) 3
🟩 (B) 4
🟦 (C) 5
🟨 (D) 6

3️⃣. One mole of H₂O contains this number of hydrogen atoms
🟥 (A) 3.01 x 10²³
🟩 (B) 6.02 x 10²³
🟦 (C) 1.204 x 10²⁴
🟨 (D) 1.204 x 10²³

4️⃣. The number of molecules in this pair are same
🟥 (A) 10g H₂ & 10g CH₄
🟩 (B) 10g H₂ & 50g CH₄
🟦 (C) 10g H₂ & 80g CH₄
🟨 (D) 10g H₂ & 16g CH₄

5️⃣. The vapour pressure of water at 100°C will be
🟥 (A) 760 torr
🟩 (B) 76 torr
🟦 (C) 14.2 psi
🟨 (D) 100 torr

6️⃣. Number of crystal systems on the basis of unit cell is
🟥 (A) 5
🟩 (B) 6
🟦 (C) 7
🟨 (D) 8

7️⃣. Capillary action in liquids is due to
🟥 (A) Viscosity
🟩 (B) Surface tension
🟦 (C) Density
🟨 (D) Fluidity

8️⃣. The rate of diffusion of CO₂ is equal to
🟥 (A) CH₄
🟩 (B) CO
🟦 (C) SO₂
🟨 (D) C₃H₈

9️⃣. The (n+l) value for 5d orbital is
🟥 (A) 4
🟩 (B) 5
🟦 (C) 6
🟨 (D) 7

1️⃣0️⃣. By emitting α-particles, ₉₂-U-²³⁸ converts into

🟥 (A) 82-Pb-208
🟩 (B) 84-Po-210
🟦 (C) 89-Ac-227
🟨 (D) 90-Th-234

1️⃣1️⃣. The maximum number of electrons in a particular sub-energy level is

🟥 (A) 2n²
🟩 (B) n²
🟦 (C) (2l+1)
🟨 (D) 2(2l+1)

1️⃣2️⃣. e/m value is minimum for positive rays when discharge tube contains
🟥 (A) Hydrogen
🟩 (B) Helium
🟦 (C) Nitrogen
🟨 (D) Oxygen

1️⃣3️⃣. The bond energy of this molecule is maximum
🟥 (A) CH₄
🟩 (B) O₂
🟦 (C) N₂
🟨 (D) Cl₂

1️⃣4️⃣. This molecule has the maximum bond angle
🟥 (A) NH₃
🟩 (B) CO₂
🟦 (C) SO₂
🟨 (D) H₂O

1️⃣5️⃣. This hydrogen halide has the highest percentage of ionic character
🟥 (A) HF
🟩 (B) HCl
🟦 (C) HBr
🟨 (D) HI

1️⃣6️⃣. This molecule has zero dipole moment
🟥 (A) NH₃
🟩 (B) CO₂
🟦 (C) H₂O
🟨 (D) HCl

1️⃣7️⃣. This is an intensive property
🟥 (A) Density
🟩 (B) Mass
🟦 (C) Mole
🟨 (D) Volume

1️⃣8️⃣. 1 cal is equal to
🟥 (A) 0.239 J
🟩 (B) 1.98 J
🟦 (C) 4.184 J
🟨 (D) 8.314 J

1️⃣9️⃣. This color has the shortest wavelength
🟥 (A) Red
🟩 (B) Blue
🟦 (C) Violet
🟨 (D) Orange

2️⃣0️⃣. 400 J of heat is supplied to a system at constant volume, the change in internal energy is
🟥 (A) 400 J
🟩 (B) −400 J
🟦 (C) 300 J
🟨 (D) 200 J

2️⃣1️⃣. For the reaction: 2NH₃ ⇌ N₂ + 3H₂, the relation between Kc and Kp is
🟥 (A) Kp = Kc
🟩 (B) Kp > Kc
🟦 (C) Kp < Kc
🟨 (D) Kp ≤ Kc

2️⃣2️⃣. The extent of reaction will be maximum for the Kc value

🟥 (A) 10⁻³
🟩 (B) 0.1
🟦 (C) 10
🟨 (D) 10³

2️⃣3️⃣. In an exothermic reaction, an increase in temperature favors
🟥 (A) Forward reaction
🟩 (B) Reverse reaction
🟦 (C) To remain in equilibrium
🟨 (D) Irreversible reaction

2️⃣4️⃣. Precipitation occurs if the product of ionic concentration is
🟥 (A) Greater than Ksp
🟩 (B) Less than Ksp
🟦 (C) Equal to Ksp
🟨 (D) Equal to Kc

2️⃣5️⃣. When 2 moles of solute are present in 2 dm³ of solution, then concentration of solution is
🟥 (A) 0.5 M
🟩 (B) 1 M
🟦 (C) 2 M
🟨 (D) 3 M

2️⃣6️⃣. This one has the highest pH value
🟥 (A) 0.01 M NaOH
🟩 (B) 0.02 M HCl
🟦 (C) 0.01 M NaHCO₃
🟨 (D) 0.1 M H₂SO₄

2️⃣7️⃣. The oxidation number of Cr in Cr₂O₇²⁻ is
🟥 (A) +2
🟩 (B) +4
🟦 (C) +6
🟨 (D) +7

2️⃣8️⃣. Universal indicator in acid gives this color
🟥 (A) Green
🟩 (B) Yellow
🟦 (C) Pink
🟨 (D) Red

2️⃣9️⃣. Human body is an example of
🟥 (A) Open system
🟩 (B) Closed system
🟦 (C) Isolated system
🟨 (D) Isochoric system

3️⃣0️⃣. The reaction 2NO₂ → 2NO + O₂ has order
🟥 (A) Zero
🟩 (B) 1st
🟦 (C) 2nd
🟨 (D) 3rd

3️⃣1️⃣. These reactions have low value of activation energy?
🟥 (A) Slow
🟩 (B) Fast
🟦 (C) Moderate
🟨 (D) Ionic

3️⃣2️⃣. The change in concentration of reacting substance in a unit time is called
🟥 (A) Rate of reaction
🟩 (B) Rate constant
🟦 (C) Specific rate constant
🟨 (D) Rate law

3️⃣3️⃣. The threshold energy of a chemical reaction is 31 kJ/mol and the average internal energy of the reactant is 12 kJ/mol, the activation energy will be

🟥 (A) 55 kJ/mol
🟩 (B) 43 kJ/mol
🟦 (C) 25 kJ/mol
🟨 (D) 19 kJ/mol

✨ Answers with Explanations ✨

1️⃣. (C) 11.2 dm³
🟦 Reason: At STP, 1 mole of any ideal gas occupies 22.4 dm³. 3.01 × 10²³ molecules is half a mole, so it occupies 11.2 dm³.

2️⃣. (C) 5
🟦 Reason: 602.10 has 5 significant figures (all digits are significant).

3️⃣. (C) 1.204 × 10²⁴
🟦 Reason: One mole of H₂O contains 2 moles of hydrogen atoms. So, 1 mole of H₂O has 2 × 6.02 × 10²³ = 1.204 × 10²⁴ hydrogen atoms.

4️⃣. (C) 10g H₂ & 80g CH₄
🟦 Reason: 10g of H₂ is 5.0 × 10²³ molecules, and 80g of CH₄ is also 5.0 × 10²³ molecules, so they have the same number of molecules.

5️⃣. (A) 760 torr
🟦 Reason: At 100°C, the vapor pressure of water is 760 torr, equal to 1 atmosphere.

6️⃣. (C) 7
🟦 Reason: There are 7 crystal systems based on the unit cell (cubic, tetragonal, orthorhombic, etc.).

7️⃣. (B) Surface tension
🟦 Reason: Capillary action occurs due to surface tension, which causes liquids to climb up small tubes.

8️⃣. (D) C₃H₈
🟦 Reason: According to Graham's law of diffusion, CO₂ diffuses slower than C₃H₈ due to its higher molar mass.

9️⃣. (D) 7
🟦 Reason: For 5d orbitals, n = 5, l = 2, so n+l = 7.

1️⃣0️⃣. (D) 90-Th-234
🟦 Reason: U-238 emits an alpha particle (He-4) to form Th-234.

1️⃣1️⃣. (D) 2(2l + 1)

🟦 Reason: The maximum number of electrons in a sub-energy level is given by the formula 2(2l + 1).

1️⃣2️⃣. (D) Oxygen
🟦 Reason: The e/m ratio for positive rays is lowest when the discharge tube contains oxygen due to its higher atomic mass compared to lighter gases.

1️⃣3️⃣. (C) N₂
🟦 Reason: The bond energy in N₂ is the highest due to the triple bond between the nitrogen atoms.

1️⃣4️⃣. (B) CO₂
🟦 Reason: CO₂ has a linear structure with a bond angle of 180°, which is the highest among the options.

1️⃣5. (A) HF
🟦 Reason: HF has the highest ionic character due to the large electronegativity difference between H and F.

1️⃣6️⃣. (B) CO₂
🟦 Reason: CO₂ has a linear structure, and its dipoles cancel out, giving it zero dipole moment.

1️⃣7️⃣. (A) Density
🟦 Reason: Density is an intensive property, meaning it does not depend on the amount of substance.

1️⃣8️⃣. (C) 4.184 J
🟦 Reason: 1 cal = 4.184 J (this is the definition of a calorie in terms of joules).

1️⃣9️⃣. (C) Violet
🟦 Reason: Violet light has the shortest wavelength in the visible spectrum.

2️⃣0️⃣. (A) 400 J
🟦 Reason: At constant volume, the change in internal energy is equal to the heat supplied (since no work is done).

2️⃣1️⃣. (B) Kp > Kc
🟦 Reason: For the reaction 2NH₃ ⇌ N₂ + 3H₂, the relationship between Kp and Kc is Kp > Kc due to the change in number of moles of gas.

2️⃣2️⃣. (D) 10³

🟦 Reason: A higher Kc value (10³) corresponds to a reaction that favors products, meaning the extent of the reaction is maximum.

2️⃣3️⃣. (B) Reverse reaction
🟦 Reason: In an exothermic reaction, increasing the temperature shifts the equilibrium to the reverse side (according to Le Chatelier's Principle).

2️⃣4️⃣. (A) Greater than Ksp
🟦 Reason: Precipitation occurs when the product of ionic concentrations exceeds the solubility product (Ksp).

2️⃣5. (B) 1 M
🟦 Reason: Concentration = moles/volume, so 2 moles in 2 dm³ gives a concentration of 1 M.

2️⃣6️⃣. (A) 0.01 M NaOH
🟦 Reason: NaOH is a strong base, and the 0.01 M NaOH solution will have the highest pH.

2️⃣7️⃣. (C) +6
🟦 Reason: In Cr₂O₇²⁻, the oxidation state of Cr is +6.

2️⃣8️⃣. (D) Red
🟦 Reason: Universal indicator turns red in acidic solutions, indicating a low pH.

2️⃣9️⃣. (A) Open system
🟦 Reason: The human body exchanges both energy and matter with the surroundings, making it an open system.

3️⃣0️⃣. (C) 2nd
🟦 Reason: The reaction 2NO₂ → 2NO + O₂ has a second-order rate law with respect to NO₂.

3️⃣1️⃣. (B) Fast
🟦 Reason: Reactions that occur quickly usually have a low activation energy.

3️⃣2️⃣. (A) Rate of reaction
🟦 Reason: The rate of reaction is defined as the change in concentration of reactants or products per unit time.

3️⃣3️⃣. (D) 19 kJ/mol

🟦 Reason: Activation energy = threshold energy - average internal energy of reactants = 31 kJ/mol - 12 kJ/mol = 19 kJ/mol.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2021 | 🔥 💡

1️⃣ The volume of 3.01 x 10²³ molecules of H₂, at S.T.P will be:

🟦 a) 11.2 dm³

🟩 b) 22.4 dm³

🟨 c) 33.6 dm³

🟥 d) 44.8 dm³

2️⃣ 602.10 has:

🟦 a) 3 significant figures

🟩 b) 4 significant figures

🟨 c) 5 significant figures

🟥 d) 6 significant figures

3️⃣ One mole of H₂O contains the number of hydrogen atoms:

🟦 a) 6.02 x 10²³

🟩 b) 1.204 x 10²⁴

🟨 c) 3.01 x 10²³

🟥 d) 1.204 x 10²³

4️⃣ The phenomenon is due to surface tension:

🟦 a) Density

🟩 b) Vapour Pressure

🟨 c) Viscosity

🟥 d) Capillary Action

5️⃣ The rate of diffusion of CO₂ is equal to:

🟦 a) CO

🟩 b) CH₄

🟨 c) C₃H₈

🟥 d) SO₂

6️⃣ This law is applied in the collection of gases over water:

🟦 a) Graham's Law of Diffusion

🟩 b) Dalton's Law

🟨 c) Avogadro's Law

🟥 d) Charles’s Law

7️⃣ Volume-volume relationship is based on:

🟦 a) Avogadro's Law

🟩 b) Dalton's Law

🟨 c) Gay-Lussac's Law

🟥 d) Boyle's Law

8️⃣ In James Chadwick's experiment, alpha particles were bombarded on:

🟦 a) Beryllium

🟩 b) Boron

🟨 c) Bromine

🟥 d) Carbon

9️⃣ This colour has the largest wavelength in the visible spectrum:

🟦 a) Red

🟩 b) Violet

🟨 c) Blue

🟥 d) Green

1️⃣0️⃣The maximum number of electrons in a particular sub-energy level is:

🟦 a) n²

🟩 b) 2n²

🟨 c) 2l + 1

🟥 d) 2(2l + 1)

1️⃣1️⃣ In the hydrogen atom spectrum, the series of lines obtained when electrons jump from higher orbits to the first orbit is called:

🟦 a) Lyman Series

🟩 b) Balmer Series

🟨 c) Brackett Series

🟥 d) Paschen Series

1️⃣2️⃣ By emitting an alpha particle, U-238 converts into:

🟦 a) Pb-208

🟩 b) Po-234

🟨 c) Ac-227

🟥 d) Th-234

1️⃣3️⃣ The range of bond energy of a hydrogen bond is:

🟦 a) 10-20 kJ/mol

🟩 b) 20-40 kJ/mol

🟨 c) 40-50 kJ/mol

🟥 d) 50-60 kJ/mol

1️⃣4️⃣ 1 Debye is equal to:

🟦 a) 3.335 x 10⁻³⁰ Cm

🟩 b) 6.02 x 10⁻²³ Cm

🟨 c) 9.11 x 10⁻¹⁹ Cm

🟥 d) 1.602 x 10⁻²⁷ Cm

1️⃣5️⃣ This molecule has the highest bond energy but the shortest bond length:

🟦 a) C ≡ C

🟩 b) C = C

🟨 c) O = O

🟥 d) N ≡ N

1️⃣6️⃣ This molecule has zero dipole moment:

🟦 a) NO₂

🟩 b) SO₂

🟨 c) CO₂

🟥 d) H₂O

1️⃣7️⃣ The octet rule is not applied to this molecule:

🟦 a) N₂

🟩 b) F₂

🟨 c) O₂

🟥 d) H₂

1️⃣8️⃣ This molecule has a linear structure:

🟦 a) CH₄

🟩 b) NH₃

🟨 c) BF₃

🟥 d) C₂H₂

1️⃣9️⃣  The number of bonds in ethyne (C₂H₂) is:

🟦 a) 2 sigma, 2 pi

🟩 b) 3 sigma, 2 pi

🟨 c) 3 sigma, 3 pi

🟥 d) 2 sigma, 3 pi

2️⃣0️⃣ This is not an intensive property:

🟦 a) Volume

🟩 b) Surface Tension

🟨 c) Viscosity

🟥 d) Boiling Point

2️⃣1️⃣At constant volume, the heat absorbed by a system is:

🟦 a) qv = ∆E

🟩 b) Qp = ∆H

🟨 c) q = E + PV

🟥 d) W = P∆V

2️⃣2️⃣ In this reaction, Kp > Kc:

🟦 a) H₂ + I₂ ⇌ 2HI

🟩 b) PCl₅ ⇌ PCl₃ + Cl₂

🟨 c) 2NO₂ ⇌ N₂O₄

🟥 d) 2SO₂ + O₂ ⇌ 2SO₃

2️⃣3️⃣ In an exothermic reaction, an increase in temperature favours:

🟦 a) Forward direction

🟩 b) Reverse direction

🟨 c) Remain at Equilibrium

🟥 d) Irreversible

2️⃣4️⃣ The reaction CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O is called:

🟦 a) Neutralization

🟩 b) Hydrolysis

🟨 c) Esterification

🟥 d) Electrolysis

2️⃣5️⃣ According to Le Chatelier's principle, the yield of products cannot be controlled with the help of:

🟦 a) Concentration

🟩 b) Catalyst

🟨 c) Pressure

🟥 d) Temperature

2️⃣6️⃣ When this salt is dissolved in water, it does not hydrolyze:

🟦 a) CH₃COONa

🟩 b) NaCl

🟨 c) Na₂CO₃

🟥 d) NaHCO₃

2️⃣7️⃣ This cation has the greatest tendency to get hydrated:

🟦 a) Na⁺

🟩 b) Mg²⁺

🟨 c) Al³⁺

🟥 d) K⁺

2️⃣8️⃣ The oxidation number of N in HNO₃ is:

🟦 a) +6

🟩 b) +5

🟨 c) +3

🟥 d) +4

2️⃣9️⃣  Its solution is basic:

🟦 a) NH₄Cl

🟩 b) Na₂CO₃

🟨 c) NaCl

🟥 d) KCl

3️⃣0️⃣ This is considered a weak electrolyte:

🟦 a) HCl

🟩 b) NaOH

🟨 c) NaCl

🟥 d) CH₃COOH

3️⃣1️⃣ The order of a photochemical reaction is:

🟦 a) First

🟩 b) Second

🟨 c) Third

🟥 d) None

3️⃣2️⃣ Powdered zinc is more reactive than a chunk of zinc due to:

🟦 a) Higher Temperature

🟩 b) Greater Volume

🟨 c) Greater Surface Area

🟥 d) Higher Pressure

3️⃣3️⃣ This compound does not contain a hydrogen bond:

🟦 a) CH₄

🟩 b) H₂O

🟨 c) HF

🟥 d) NH₃

3️⃣4️⃣ Motor oil grading is based on:

🟦 a) Surface Tension

🟩 b) Viscosity

🟨 c) Vapour Pressure

🟥 d) Boiling Point

3️⃣5️⃣ The colour of the universal indicator in a neutral solution is:

🟦 a) Red

🟩 b) Blue

🟨 c) Pink

🟥 d) Green

3️⃣6️⃣ Two solid compounds having the same crystal structure are called:

🟦 a) Allotropes

🟩 b) Isomorphous

🟨 c) Polymorphous

🟥 d) Isotopes

3️⃣7️⃣ This particle has mass 1836 times that of an electron:

🟦 a) Proton

🟩 b) Neutron

🟨 c) Meson

🟥 d) Hyperon

3️⃣8️⃣ This is not the same in Na⁺ (Z = 11), Mg²⁺ (Z = 12), and Al³⁺ (Z = 13):

🟦 a) Number of shells

🟩 b) Number of electrons

🟨 c) Electronic configuration

🟥 d) Number of protons

3️⃣9️⃣  The (n + 1) value for a 4f orbital is:

🟦 a) 4

🟩 b) 5

🟨 c) 6

🟥 d) 7

4️⃣0️⃣ This pair of compounds has the same empirical formula:

🟦 a) C₂H₄ and C₂H₂

🟩 b) CH₄ and C₂H₆

🟨 c) HCHO and CH₃COOH

🟥 d) C₂H₆ and C₂H₆

4️⃣1️⃣ This molecule has two lone pairs and two bond pair electrons:

🟦 a) NH₃

🟩 b) CCl₄

🟨 c) H₂O

🟥 d) BeCl₂

4️⃣2️⃣  The change in concentration per unit time is called the:

🟦 a) Order of reaction

🟩 b) Rate of reaction

🟨 c) Rate constant

🟥 d) Equilibrium constant

✨ Answers & Explanations ✨

1️⃣ The volume of 3.01 x 10²³ molecules of H₂, at S.T.P will be:

🟩 a) 11.2 dm³

Reason: At STP, 1 mole of any ideal gas occupies 22.4 dm³. 3.01 x 10²³ molecules = half mole.

2️⃣ 602.10 has:

🟩 c) 5 significant figures

Reason: 602.10 has 5 significant figures as the zero is significant after the decimal.

3️⃣ One mole of H₂O contains the number of hydrogen atoms:

🟩 b) 1.204 x 10²⁴

Reason: One mole of H₂O contains 2 moles of hydrogen atoms (since H₂O has two hydrogen atoms per molecule). Therefore, 2 moles x (6.02 x 10²³) = 1.204 x 10²⁴ hydrogen atoms.

4️⃣ The phenomenon is due to surface tension:

🟩 d) Capillary Action

Reason: Capillary action occurs due to surface tension, where liquid moves against gravity through narrow spaces (e.g., inside a tube).

5️⃣ The rate of diffusion of CO₂ is equal to:

🟩 c) C₃H₈

Reason: Gases with same molar mass will have same diffusion rate

6️⃣This law is applied in the collection of gases over water:

🟩 b) Dalton's Law

Reason: Dalton's Law of Partial Pressures is used when collecting gases over water. It relates the total pressure of a gas mixture to the partial pressures of the individual gases.

7️⃣ Volume-volume relationship is based on:

🟦 c) Gay-Lussac's Law

Reason: Gay-Lussac's Law states that at a given temperature and pressure, gases combine or form in a simple whole number ratio of their volumes, which applies in volume-volume relationships.

8️⃣ In James Chadwick's experiment, alpha particles were bombarded on:

🟦 a) Beryllium

Reason: James Chadwick bombarded beryllium with alpha particles to discover the neutron.

9️⃣ This colour has the largest wavelength in the visible spectrum:

🟦 a) Red

Reason: In the visible spectrum, red light has the longest wavelength (around 620–750 nm).

1️⃣0️⃣ The maximum number of electrons in a particular sub-energy level is:

🟩 d) 2(2l+1)

Reason: The maximum number of electrons in an energy level is given by the formula 2(2l+1), where n is the principal quantum number.

1️⃣1️⃣ In the hydrogen atom spectrum, the series of lines obtained when electrons jump from higher orbits to the first orbit is called:

🟦 a) Lyman Series

Reason: The Lyman series corresponds to the transitions where electrons fall to the first energy level of hydrogen, producing ultraviolet light.

1️⃣2️⃣ By emitting an alpha particle, U-238 converts into:

🟦 d) Th-234

Reason: When uranium-238 emits an alpha particle, it transforms into thorium-234, reducing the atomic number by 2.

1️⃣3️⃣ The range of bond energy of a hydrogen bond is:

🟩 b) 20-40 kJ/mol

Reason: Hydrogen bonds typically have bond energies in the range of 20-40 kJ/mol.

1️⃣4️⃣ [14] 1 Debye is equal to:

🟦 a) 3.335 x 10⁻³⁰ Cm

Reason: 1 Debye is a unit of dipole moment, and its value is 3.335 x 10⁻³⁰ Cm.

1️⃣5️⃣ [15] This molecule has the highest bond energy but the shortest bond length:

🟩 d) N≡N

Reason: The nitrogen-nitrogen triple bond (N≡N) has the highest bond energy and the shortest bond length compared to other molecules.

1️⃣6️⃣ [16] This molecule has zero dipole moment:

🟦 c) CO₂

Reason: CO₂ has a linear structure with polar bonds, but the dipoles cancel out, giving the molecule a zero dipole moment.

1️⃣7️⃣  The octet rule is not applied to this molecule:

🟦 d) H₂

Reason: Hydrogen only follows the duet rule, which allows it to have two electrons in its valence shell.

1️⃣8️⃣ This molecule has a linear structure:

🟩 d) C₂H₂

Reason: Ethyne (C₂H₂) has a linear structure due to the triple bond between the two carbon atoms.

1️⃣9️⃣ The number of bonds in ethyne (C₂H₂) is:

🟩 b) 3 sigma, 2 pi

Reason: In C₂H₂, there are 3 sigma bonds (one from the C-H bond and two from the C≡C bond) and 2 pi bonds from the C≡C triple bond.

2️⃣0️⃣ This is not an intensive property:

🟦 a) Volume

Reason: Volume is an extensive property, meaning it depends on the amount of substance, whereas surface tension, viscosity, and boiling point are intensive properties.

2️⃣1️⃣ At constant volume, the heat absorbed by a system is:

🟦 a) qv = ∆E

Reason: When the volume is constant, the heat absorbed (qv) is equal to the change in internal energy (∆E).

2️⃣2️⃣ In this reaction, Kp > Kc:

🟩 b) PCl₅ ⇌ PCl₃ + Cl₂

Reason: Kp and Kc are related by the equation Kp​ = Kc​(RT)▵ⁿ. In reactions involving gases, Kp is greater than Kc when the number of moles of gaseous products exceeds the number of moles of reactants.

2️⃣3️⃣ In an exothermic reaction, an increase in temperature favours:

🟩 b) Reverse direction

Reason: According to Le Chatelier's principle, increasing the temperature shifts the equilibrium towards the endothermic (reverse) direction in an exothermic reaction.

2️⃣4️⃣ The reaction CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O is called:

🟩 c) Esterification

Reason: Esterification is the reaction between an alcohol and an acid to form an ester and water.

2️⃣5️⃣ According to Le Chatelier's principle, the yield of products cannot be controlled with the help of:

🟩 b) Catalyst

Reason: A catalyst only speeds up the rate of the reaction and does not change the equilibrium or the yield of products.

2️⃣6️⃣ When this salt is dissolved in water, it does not hydrolyze:

🟩 b) NaCl

Reason: NaCl is a neutral salt formed from a strong acid (HCl) and a strong base (NaOH), so it does not undergo hydrolysis in water.

2️⃣7️⃣ This cation has the greatest tendency to get hydrated:

🟦 c) Al³⁺

Reason: Al³⁺ has a high charge density, making it highly polar and more likely to attract water molecules.

2️⃣8️⃣The oxidation number of N in HNO₃ is:

🟩 b) +5

Reason: In HNO₃, hydrogen has an oxidation number of +1 and oxygen -2. Solving for nitrogen gives an oxidation state of +5.

2️⃣9️⃣ Its solution is basic:

🟩 b) Na₂CO₃

Reason: Na₂CO₃ is a basic salt formed from a strong base (NaOH) and a weak acid (H₂CO₃), and its solution is basic.

3️⃣0️⃣ This is considered a weak electrolyte:

🟦 d) CH₃COOH

Reason: Acetic acid (CH₃COOH) is a weak electrolyte because it only partially dissociates in water.

3️⃣1️⃣  The order of a photochemical reaction is:

🟦 a) Zero

Reason: Photochemical reactions typically follow zero-order kinetics, as the reaction rate does not depend on the concentration of reactants

3️⃣2️⃣ Powdered zinc is more reactive than a chunk of zinc due to:

🟦 c) Greater Surface Area

Reason: Powdered zinc has a larger surface area for reaction, making it more reactive compared to a solid chunk of zinc.

3️⃣3️⃣  This compound does not contain a hydrogen bond:

🟦 a) CH₄

Reason: CH₄ (methane) does not form hydrogen bonds because it lacks highly electronegative atoms (like N, O, or F) bonded to hydrogen.

3️⃣4️⃣ Motor oil grading is based on:

🟩 b) Viscosity

Reason: Motor oil grading is based on its viscosity, which determines how easily the oil flows.

3️⃣5️⃣ The colour of the universal indicator in a neutral solution is:

🟩 d) Green

Reason: In a neutral solution, the universal indicator turns green, indicating a pH of 7.

3️⃣6️⃣ Two solid compounds having the same crystal structure are called:

🟩 b) Isomorphous

Reason: Isomorphous compounds have the same crystal structure but may differ in chemical composition.

3️⃣7️⃣ This particle has mass 1836 times that of an electron:

🟦 a) Proton

Reason: A proton has a mass approximately 1836 times that of an electron.

3️⃣8️⃣  This is not the same in Na⁺ (Z = 11), Mg²⁺ (Z = 12), and Al³⁺ (Z = 13):

🟦 d) number of protons

Reason: The number of protons differs in these ions because of their varying atomic numbers. 

3️⃣9️⃣ The (n + 1) value for a 4f orbital is:

🟩 d) 7

Reason: The (n + 1) value for a 4f orbital is 7, as the principal quantum number for the f-orbital is n = 4.

4️⃣0️⃣ This pair of compounds has the same empirical formula:

🟩 c) HCHO and CH₃COOH

Reason: Both HCHO and CH₃COOH have the same empirical formula of CH₃.

4️⃣1️⃣ This molecule has two lone pair and two bond pair electrons:

🟩 c) H₂O

Reason: H₂O has two lone pairs on oxygen and two bond pairs (from the H atoms).

4️⃣2️⃣ The change in concentration per unit time is called the:

🟩 b) Rate of reaction

Reason: The rate of reaction refers to the change in concentration of reactants or products per unit time.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2019 | 🔥 💡

1️⃣ This number has five significant figures:

🟦 a) 391.10

🟩 b) 300002

🟨 c) 30000

🟥 d) 10300

2️⃣ At STP, the volume of 3.01 x 10²³ molecules of H₂ gas is:

🟦 a) 22.5 dm³

🟩 b) 22.4 dm³

🟨 c) 11.2 dm³

🟥 d) 2.24 dm³

3️⃣An ideal gas obeys gas laws at:

🟦 a) All temperature & pressures

🟩 b) High pressure

🟨 c) High temperature

🟥 d) Low temperature

4️⃣ The process of direct conversion of solid into vapour is called:

🟦 a) Condensation

🟩 b) Sublimation

🟨 c) Evaporation

🟥 d) Neutralization

5️⃣ Capillary action of liquids is due to:

🟦 a) Surface tension

🟩 b) Density

🟨 c) Fluidity

🟥 d) Viscosity

6️⃣ The colour has the shortest wavelength in the visible spectrum of light:

🟦 a) Red

🟩 b) Violet

🟨 c) Green

🟥 d) Yellow

7️⃣ This series of lines is produced when the electron jumps from the 4th orbit to the 2nd orbit:

🟦 a) Lyman

🟩 b) Balmer

🟨 c) Brackett

🟥 d) Paschen

8️⃣ The maximum number of electrons that can be accommodated in the f-orbital is:

🟦 a) 7

🟩 b) 10

🟨 c) 14

🟥 d) 15

9️⃣ This hydrogen halide has the highest percentage of ionic character:

🟦 a) HF

🟩 b) HCl

🟨 c) HBr

🟥 d) HI

1️⃣0️⃣ (n + l) value for the 5d orbital is:

🟦 a) 4

🟩 b) 5

🟨 c) 6

🟥 d) 7

1️⃣1️⃣ This molecule has zero dipole moment:

🟦 a) NH₃

🟩 b) CO₂

🟨 c) HCl

🟥 d) H₂O

1️⃣2️⃣ 1 Debye is equal to:

🟦 a) 3.335 x 10⁻²³ Cm

🟩 b) 2.25 x 10⁻¹³ Cm

🟨 c) 3.335 x 10⁻³⁰ Cm

🟥 d) 3.4 x 10⁻⁴⁰ Cm

1️⃣ 3️⃣ One joule is equal to:

🟦 a) 0.239 cal

🟩 b) 0.391 cal

🟨 c) 0.398 cal

🟥 d) 4.184 cal

1️⃣4️⃣ Universal indicator in an acid gives:

🟦 a) Green colour

🟩 b) Yellow colour

🟨 c) Pink colour

🟥 d) Red colour

1️⃣5️⃣ The oxidation number of Mn in K₂MnO₄ is:

🟦 a) +2

🟩 b) +4

🟨 c) +6

🟥 d) +7

1️⃣6️⃣ A powdered solid is more reactive than its chunks due to its:

🟦 a) Greater surface area

🟩 b) High pressure

🟨 c) Greater volume

🟥 d) Higher temperature

1️⃣7️⃣ In the following reaction, Kp > Kc:

🟦 a) H₂ + I₂ ⇌ 2HI

🟩 b) PCl₅ ⇌ PCl₃ + Cl₂

🟨 c) 2SO₂ + O₂ ⇌ 2SO₃

🟥 d) 2NO₂ ⇌ N₂O₄

✨ Answers & Explanations ✨

1️⃣ Answer: 🟩 a) 391.10

Reason: The number 391.10 has five significant figures .

2️⃣ Answer: 🟩 c) 11.2 dm³

Reason: At STP, one mole of any ideal gas occupies 22.4 dm³. 3.01 x 10²³ molecules = half mole of H₂.

3️⃣Answer: 🟩 a) All temperature and pressure

Reason: Ideal gases behave according to the gas laws at temperature and pressure

4️⃣Answer: 🟩 b) Sublimation

Reason: Sublimation is the direct conversion of a solid into a vapor without passing through the liquid phase (e.g., dry ice).

5️⃣Answer: 🟩 a) Surface tension

Reason: Capillary action occurs because of the surface tension of liquids, which causes the liquid to rise in narrow tubes.

6️⃣ Answer: 🟩 b) Violet

Reason: Violet light has the shortest wavelength (around 380–450 nm) in the visible spectrum.

7️⃣ Answer: 🟩 b) Balmer

Reason: The Balmer series corresponds to electron transitions from higher orbits to the 2nd orbit of the hydrogen atom, producing visible light.

8️⃣ Answer: 🟩 c) 14

Reason: The f-orbital can hold a maximum of 14 electrons because there are 7 sublevels (each can hold 2 electrons).

9️⃣ Answer: 🟩 a) HF

Reason: HF has the highest ionic character because of the significant electronegativity difference between hydrogen and fluorine.

1️⃣0️⃣Answer: 🟩 d) 7

Reason: For the 5d orbital, n = 5, and l = 2 (for d-orbitals), so (n + l) = 5 + 2 = 7.

1️⃣1️⃣ Answer: 🟩 b) CO₂

Reason: CO₂ has a linear structure, and the dipole moments of the two C=O bonds cancel out, resulting in zero dipole moment.

1️⃣2️⃣ Answer: 🟩 c) 3.335x10^-30Cm Cm

Reason: 1 Debye is equivalent to 3.335x10^-30Cm Cm, a unit used to measure the dipole moment.

1️⃣ 3️⃣ Answer: 🟩 a) 0.239 cal

Reason: 1 joule is equal to 4.184 calories, which is a standard conversion for energy units.

1️⃣4️⃣ Answer: 🟩 d) Red colour

Reason: In an acidic solution, the universal indicator turns red, which indicates a low pH.

1️⃣5️⃣ Answer: 🟦 c) +6

Reason: In K₂MnO₄, potassium has an oxidation number of +1, and oxygen is -2. Solving for Mn gives an oxidation number of +6.

1️⃣6️⃣ Answer: 🟩 a) Greater surface area

Reason: A powdered solid has a much larger surface area for reactions compared to a large chunk of solid, making it more reactive.

1️⃣7️⃣ Answer: 🟩 b) PCl₅ ⇌ PCl₃ + Cl₂

Reason: Kp > Kc when the number of moles of gaseous products is greater than the number of moles of gaseous reactants (in this case, 2 moles of gas are produced from 1 mole).

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2018 | 🔥 💡

1️⃣ This is not an extensive property:

🟦 a) Internal energy

🟩 b) Enthalpy

🟨 c) Density

🟥 d) Entropy

2️⃣ The equation for Ksp for CaF₂ is:

🟦 a) Ksp = [Ca²⁺][F⁻]

🟩 b) Ksp = [Ca²⁺][F⁻]²

🟨 c) Ksp = [Ca⁺][F⁻]

🟥 d) Ksp = [Ca⁺][F⁻]²

3️⃣ This ion has the greatest degree of hydration:

🟦 a) Na⁺

🟩 b) Mg²⁺

🟨 c) Al³⁺

🟥 d) K⁺

4️⃣ The molarity of a solution containing 53 g Na₂CO₃ dissolved in 1 dm³ solution will be:

🟦 a) 0.1

🟩 b) 0.01

🟨 c) 0.02

🟥 d) 0.5

5️⃣ The reaction: 2NO₂ ⇌ 2NO + O₂ is of:

🟦 a) Zero order

🟩 b) 1st order

🟨 c) 2nd order

🟥 d) 3rd order

6️⃣ The volume of 3.01 x 10²³ molecules of N₂ gas at STP will be:

🟦 a) 3 dm³

🟩 b) 11.2 dm³

🟨 c) 22.4 dm³

🟥 d) 28 dm³

7️⃣ The characteristic of 10³ is:

🟦 a) 2

🟩 b) 3

🟨 c) 4

🟥 d) 5

8️⃣ If a = b ≠ c and α = β = γ = 90°, then the crystal structure is:

🟦 a) Cubic

🟩 b) Orthorhombic

🟨 c) Tetragonal

🟥 d) Triclinic

9️⃣ The rate of diffusion of CO₂ is equal to that of:

🟦 a) CH₄

🟩 b) CO

🟨 c) C₃H₈

🟥 d) SO₂

1️⃣0️⃣ The S.I. unit of viscosity is:

🟦 a) Poise

🟩 b) Millipoise

🟨 c) Centipoise

🟥 d) N.s.m⁻²

1️⃣1️⃣  The maximum number of electrons in a particular energy level is:

🟦 a) 2n²

🟩 b) n²

🟨 c) (2l + 1)

🟥 d) 2(2l + 1)

1️⃣2️⃣ The energy of each quantum of radiation is directly proportional to its:

🟦 a) Frequency

🟩 b) Wavelength

🟨 c) Wave number

🟥 d) Source of energy

1️⃣3️⃣These radioactive rays are non-material in nature:

🟦 a) α-rays

🟩 b) β-rays

🟨 c) γ-rays

🟥 d) Canal rays

1️⃣4️⃣ The potential energy of an electron can be denoted by:

🟦 a) Ze²/r²

🟩 b) Ze/r

🟨 c) Ze²/r

🟥 d) −Ze²/r

1️⃣5️⃣ This molecule has the maximum bond angle:

🟦 a) CS₂

🟩 b) NH₃

🟨 c) SO₂

🟥 d) H₂O

1️⃣6️⃣ The energy of this bond is the greatest:

🟦 a) CH₄

🟩 b) O₂

🟨 c) N₂

🟥 d) Cl₂

1️⃣7️⃣ The dipole moment of this molecule is zero:

🟦 a) NH₃

🟩 b) CO₂

🟨 c) H₂O

🟥 d) HCl

✨ Answers & Explanations ✨

1️⃣  Answer: 🟨 c) Density

Reason: Density is an intensive property, meaning it does not depend on the amount of substance. Extensive properties depend on the quantity of matter.

2️⃣ Answer: 🟩 b) Ksp = [Ca²⁺][F⁻]²

Reason: For the dissociation of CaF₂: CaF₂ ⇌ Ca²⁺ + 2F⁻. The Ksp expression accounts for two fluoride ions per calcium ion.

3️⃣ Answer: 🟩 c) Al³⁺

Reason: The degree of hydration increases with the charge and smaller size of the ion. Al³⁺, with a +3 charge, has the highest degree of hydration.

4️⃣ Answer: 🟨 d) 0.5

Reason: Molarity = (moles of solute) / (volume of solution in liters). 53 g Na₂CO₃ = (53 / 106) mol = 0.5 mol. The molarity = 0.5 mol / 1 dm³ = 0.5 M.

5️⃣ Answer: 🟩 c) 2nd order

Reason: The reaction 2NO₂ ⇌ 2NO + O₂ is of 2nd order with respect to NO₂, as the rate of reaction depends on the square of concentration of NO₂.

6️⃣ Answer: 🟩 b) 11.2 dm³

Reason: At STP (standard temperature and pressure), one mole of gas occupies 22.4 dm³. 3.01 x 10²³ molecules represent 0.5 mole of N₂ gas.

7️⃣ Answer: 🟩 b) 3

Reason: The characteristic of 10³ is 3, as it has three significant digits.

8️⃣Answer: 🟩 c) Tetragonal

Reason: When α = β = γ = 90° and a ≠ b ≠ c, the crystal system is tetragonal, where two axes are equal, and the third is different.

9️⃣ Answer: 🟦 c) 

Reason: According to Graham's Law of Diffusion, gases with same molar masses would have same diffusion rate. 

1️⃣ 0️⃣ Answer: 🟩 d) N.s.m⁻²

Reason: The SI unit of viscosity is Newton-second per square meter (N.s.m⁻²), which is equivalent to Pa.s.

1️⃣1️⃣ Answer: 🟦 a) 2n²

Reason: The maximum number of electrons that can be accommodated in a particular energy level is given by 2n², where n is the principal quantum number.

1️⃣2️⃣ Answer: 🟦 a) Frequency

Reason: The energy of each quantum of radiation is directly proportional to its frequency, as described by Planck's equation: E = hν.

1️⃣3️⃣ Answer: 🟩 c) γ-rays

Reason: Gamma rays are electromagnetic radiation and are non-material in nature, unlike α and β rays, which are particles.

1️⃣4️⃣ Answer: 🟦 d) −Ze²/r

Reason: The potential energy of an electron in an atom is given by the equation −Ze²/r, where Z is the atomic number and r is the distance from the nucleus.

1️⃣5️⃣ Answer: 🟦 a) CS₂

Reason: CS₂ has a linear molecular geometry, and the bond angle between the C–S bonds is 180°, the maximum possible bond angle for a molecule.

1️⃣6️⃣ Answer: 🟨 c) N₂

Reason: The triple bond in N₂ is the strongest, with the highest bond energy and shortest bond length compared to other molecules.

1️⃣7️⃣ Answer: 🟩 b) CO₂

Reason: CO₂ has a linear structure, and the dipole moments of the two C=O bonds cancel each other out, resulting in a zero dipole moment.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2017 | 🔥 💡

1️⃣. In the diagram below, the name of the reverse process of B is:

🟥 (A) Evaporation
🟩 (B) Condensation
🟦 (C) Sublimation
🟨 (D) Fusion

2️⃣. If a = b ≠ c; and α = β = γ = 90°, then crystal structure is:
🟥 (A) Cubic
🟩 (B) Orthorhombic
🟦 (C) Tetragonal
🟨 (D) Triclinic

3️⃣. The uncertainty principle is applied to:
🟥 (A) Aero plane
🟩 (B) Cricket ball
🟦 (C) Electron
🟨 (D) Earth

4️⃣. This is an intensive property:
🟥 (A) Internal energy
🟩 (B) Enthalpy
🟦 (C) Volume
🟨 (D) Reflective index

5️⃣. Quantum number values for 3d orbital is:
🟥 (A) n = 3, l = 2
🟩 (B) n = 3, l = 3
🟦 (C) n = 2, l = 2
🟨 (D) n = 3, l = 0

6️⃣. This molecule has the maximum bond angle:
🟥 (A) NH₃
🟩 (B) CO₂
🟦 (C) SO₂
🟨 (D) H₂O

7️⃣. For a reversible reaction, if the concentrations of the reactants are doubled, then the equilibrium constant will:
🟥 (A) Also be doubled
🟩 (B) Be halved
🟦 (C) Remain same
🟨 (D) Be ¼th

8️⃣. The molarity of solution containing 4 g NaOH dissolved in 10 ml solution is:
🟥 (A) 0.4 M
🟩 (B) 0.1 M
🟦 (C) 10 M
🟨 (D) 1.0 M

9️⃣. A powdered solid is more reactive than its chunks due to:
🟥 (A) Higher surface area
🟩 (B) Higher temp.
🟦 (C) Higher pressure
🟨 (D) Greater volume

1️⃣0️⃣. The number of bonds in C₂H₂ molecule is:
🟥 (A) One σ and two π
🟩 (B) 3 σ and one π
🟦 (C) 3 σ and two π
🟨 (D) 2 σ and two π

1️⃣1️⃣. Most of the radiations coming out from pitch blende were:

🟥 (A) Protons
🟩 (B) Electrons
🟦 (C) Positron
🟨 (D) Neutrons

1️⃣2️⃣. The energy of each quantum of radiation is directly proportional to:
🟥 (A) Frequency
🟩 (B) Wave number
🟦 (C) Wavelength
🟨 (D) Source of energy

1️⃣3️⃣. This has five significant figures:
🟥 (A) 0.00215
🟩 (B) 21500
🟦 (C) 21.5210
🟨 (D) 21.521

1️⃣4️⃣. The melting points of those substances which expand on melting increase when the pressure is:
🟥 (A) Decreased
🟩 (B) Increased
🟦 (C) Kept unchanged
🟨 (D) Atmospheric

1️⃣5. While considering the rule of significant figures, the simplified result of 3.1 + 14.367 is:
🟥 (A) 17.467
🟩 (B) 17.47
🟦 (C) 17.50
🟨 (D) 17.5

1️⃣6️⃣. The atmospheric pressures recorded in different places at the same time are given below:

Water boils first in this city:
🟥 (A) Nathiagali
🟩 (B) Hunza
🟦 (C) Murree
🟨 (D) Gilgit

1️⃣7️⃣. The number of orbitals in each energy level is given by the formula:
🟥 (A) 2n²
🟩 (B) (2l+1)
🟦 (C) 2(2l+1)
🟨 (D) n²

✨ Answers & Explanations ✨

1️⃣. (B) Condensation
🟩 Reason: The reverse of evaporation is condensation, where a gas turns into a liquid.

2️⃣. (B) Orthorhombic
🟩 Reason: In the orthorhombic crystal structure, a = b ≠ c, and α = β = γ = 90°.

3️⃣. (C) Electron
🟦 Reason: The uncertainty principle applies to small particles like electrons, where both position and momentum cannot be precisely known simultaneously.

4️⃣. (D) Reflective index
🟨 Reason: The reflective index is an intensive property as it does not depend on the amount of material.

5️⃣. (A) n = 3, l = 2
🟦 Reason: For a 3d orbital, n = 3 and l = 2 (d-orbitals).

6️⃣. (B) CO₂
🟩 Reason: CO₂ has a linear structure, giving it the maximum bond angle of 180°.

7️⃣. (C) Remain same
🟦 Reason: The equilibrium constant is independent of the concentration of reactants, so it remains the same.

8️⃣. (B) 0.1 M
🟩 Reason: Molarity = moles/volume. 4g of NaOH in 10 ml (0.01 L) gives 0.1 M.

9️⃣. (A) Higher surface area
🟩 Reason: A powdered solid has more surface area for reaction, making it more reactive.

1️⃣0️⃣. (B) Three σ and two π
🟦 Reason: In C₂H₂, the triple bond consists of one sigma (σ) bond and two pi (π) bonds.

1️⃣1️⃣. (B) Electrons

🟩 Reason: Pitchblende mainly emits electrons in the form of beta radiation.

1️⃣2️⃣. (A) Frequency
🟦 Reason: The energy of a quantum of radiation is directly proportional to the frequency (E = hf).

1️⃣3️⃣. (C) 21.5210
🟦 Reason: 21.5210 has 5 significant figures (all digits are significant).

1️⃣4️⃣. (B) Increased
🟩 Reason: When pressure is increased, the melting point of substances that expand on melting increases.

1️⃣5️⃣. (D) 17.5
🟨 Reason: For addition, the result should be rounded to the least decimal place, which is 1 decimal point.

1️⃣6️⃣. (D) Gilgit
🟦 Reason: Water boils first at the lowest pressure, which is Gilgit at 600 torr.

1️⃣7️⃣. (D) n²
🟨 Reason: The number of orbitals in an energy level is given by the formula n² (where n is the principal quantum number).

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2016 | 🔥 💡

1️⃣. The bond angle is maximum in this molecule:

🟥 (A) CH₄

🟩 (B) CO₂

🟦 (C) H₂O

🟨 (D) NH₃

2️⃣. Glass is a/an:

🟥 (A) Crystalline solid

🟩 (B) Amorphous solid

🟦 (C) Covalent solid

🟨 (D) Ionic solid

3️⃣. Bond energy is the greatest for:

🟥 (A) CH₄

🟩 (B) O₂

🟦 (C) N₂

🟨 (D) Cl₂

4️⃣. The bulk properties of a system, which are easily measurable, are known as ……. properties:

🟥 (A) Microscopic

🟩 (B) Macroscopic

🟦 (C) Chemical

🟨 (D) Physical

5️⃣. The characteristic of 10³ is:

🟥 (A) 2

🟩 (B) 3

🟦 (C) 4

🟨 (D) 5

6️⃣. This molecule has zero dipole moment:

🟥 (A) NH₃

🟩 (B) CO₂

🟦 (C) H₂O

🟨 (D) HCl

7️⃣. The molarity of a solution containing 20 g NaOH dissolved into 1 dm³ solution will be:

🟥 (A) 0.1

🟩 (B) 0.5

🟦 (C) 1

🟨 (D) 2

8️⃣. The octet rule is not valid for this molecule:

🟥 (A) N₂

🟩 (B) CO₂

🟦 (C) O₂

🟨 (D) H₂

9️⃣. This ion has the greatest degree of hydration:

🟥 (A) Na⁺

🟩 (B) Mg²⁺

🟦 (C) Al³⁺

🟨 (D) K⁺

1️⃣0️⃣. The volume of 3.01 × 10²³ molecules of N₂ gas at STP will be:

🟥 (A) 3 dm³

🟩 (B) 11.2 dm³

🟦 (C) 22.4 dm³

🟨 (D) 28 dm³

1️⃣1️⃣. Rate = K [NH₃]². Keeping the other conditions the same, if the concentration of NH₃ is increased by four times, then the initial rate of reaction will be:

🟥 (A) 2X

🟩 (B) 4X

🟦 (C) 8X

🟨 (D) 16X

1️⃣2️⃣. This is not an extensive property:

🟥 (A) Entropy

🟩 (B) Viscosity

🟦 (C) Enthalpy

🟨 (D) Internal energy

1️⃣3️⃣. The extent of the reaction will be maximum for this Kc value:

🟥 (A) 10⁻¹³

🟩 (B) 10³

🟦 (C) 0.1

🟨 (D) 10

1️⃣4️⃣. This hydrogen halide has the highest percentage of ionic character:

🟥 (A) HF

🟩 (B) HCl

🟦 (C) HBr

🟨 (D) HI

1️⃣5️⃣. These have low values of activation energy:

🟥 (A) Moderate reactions

🟩 (B) Fast reactions

🟦 (C) Ionic reactions

🟨 (D) Slow reactions

1️⃣6️⃣. Gases behave ideally at these conditions:

🟥 (A) High pressures and high temperatures

🟩 (B) High pressures and low temperatures

🟦 (C) Low pressures & high temperatures

🟨 (D) Low pressures and low temperatures

1️⃣7️⃣. The yield of ammonia in Haber’s process is favoured at:

🟥 (A) High pressure and high temperature

🟩 (B) High pressure and low temperature

🟦 (C) Low pressure and low temperature

🟨 (D) Low pressure and high temperature

✨ Answers & Explanations ✨

1️⃣. (C) H₂O

🟦 Reason: The bond angle in H₂O is 104.5°, which is the largest among the options due to its bent structure.

2️⃣. (B) Amorphous solid

🟩 Reason: Glass is an amorphous solid because its atoms are not arranged in a regular, repeating pattern.

3️⃣. (C) N₂

🟦 Reason: N₂ has the highest bond energy due to the strong triple bond between nitrogen atoms.

4️⃣. (B) Macroscopic

🟩 Reason: Macroscopic properties are those that can be measured and observed directly, such as temperature, pressure, and volume.

5️⃣. (B) 3

🟩 Reason: 10³ is written in scientific notation, and the exponent is 3, indicating 3 significant digits.

6️⃣. (B) CO₂

🟩 Reason: CO₂ is a linear molecule, and its dipoles cancel out, resulting in a zero dipole moment.

7️⃣. (B) 0.5

🟩 Reason: The molarity of NaOH is calculated as moles of solute divided by volume of solution. Molarity = (20 g / 40 g/mol) / 1 dm³ = 0.5 M.

8️⃣. (D) H₂

🟨 Reason: The octet rule does not apply to H₂, which follows the duet rule (only 2 electrons in its valence shell).

9️⃣. (C) Al³⁺

🟦 Reason: Al³⁺ has the highest charge density, leading to the greatest degree of hydration.

1️⃣0️⃣. (C) 22.4 dm³

🟦 Reason: 3.01 × 10²³ molecules correspond to 1 mole of N₂, and at STP, 1 mole of gas occupies 22.4 dm³.

1️⃣1️⃣. (D) 16X

🟨 Reason: The rate law is proportional to the square of the concentration of NH₃. If the concentration increases by 4 times, the rate increases by 16 times (4² = 16).

1️⃣2️⃣. (B) Viscosity

🟩 Reason: Viscosity is not an extensive property because it depends on the type of substance, not the amount.

1️⃣3️⃣. (B) 10³

🟩 Reason: The extent of the reaction will be maximum for a high Kc value (10³) as it indicates a high concentration of products.

1️⃣4️⃣. (A) HF

🟦 Reason: HF has the highest ionic character due to the large electronegativity difference between hydrogen and fluorine.

1️⃣5️⃣. (C) Ionic reactions

🟦 Reason: Ionic reactions typically have low activation energies because the reactants are already ionized and ready to react.

1️⃣6️⃣. (C) Low pressures & high temperatures

🟦 Reason: Gases behave ideally at low pressures and high temperatures, where intermolecular forces are negligible.

1️⃣7️⃣. (B) High pressure and low temperature

🟩 Reason: According to Le Chatelier’s principle, high pressure and low temperature favor the formation of ammonia in the Haber process.

🎉📚 Karachi Board XI Chemistry MCQs Past Paper 2015 | 🔥 💡

1️⃣. The following pair of ions is isoelectronic:

🟥 (A) Na⁺ and Mg²⁺

🟩 (B) F⁻ and O²⁻

🟦 (C) Li⁺ and Na⁺

🟨 (D) S²⁻ and O²⁻

2️⃣. This one of the following colours has the shortest wavelength:

🟥 (A) Red

🟩 (B) Blue

🟦 (C) Violet

🟨 (D) Orange

3️⃣. The SI unit of dipole moment is:

🟥 (A) Coulomb-metre

🟩 (B) Dyne/cm

🟦 (C) Poise

🟨 (D) Debye

4️⃣. 1 cal is equal to:

🟥 (A) 0.239 J

🟩 (B) 1.98 J

🟦 (C) 4.184 J

🟨 (D) 8.314 J

5️⃣. When 2 moles of solute are present in 2 dm³ of solution, then the concentration of the solution is:

🟥 (A) 0.5 M

🟩 (B) 1 M

🟦 (C) 2 M

🟨 (D) 3 M

6️⃣. The oxidation number of Sulphur in NaHSO₄ is:

🟥 (A) -2

🟩 (B) 0

🟦 (C) +4

🟨 (D) +6

7️⃣. This is not a primary bond:

🟥 (A) Ionic bond

🟩 (B) Covalent bond

🟦 (C) Dative bond

🟨 (D) Hydrogen bond

8️⃣. For the reaction, 2NH₃ ⇌ N₂ + 3H₂, the relationship between Kc and Kp is:

🟥 (A) Kp = Kc

🟩 (B) Kp > Kc

🟦 (C) Kp < Kc

🟨 (D) Kp ≤ Kc

9️⃣. Conduction in metals is due to the movement of:

🟥 (A) Ions

🟩 (B) Electrons

🟦 (C) Protons

🟨 (D) Atoms

1️⃣0️⃣. The (n+l) value for 5d orbital is:

🟥 (A) 4

🟩 (B) 5

🟦 (C) 6

🟨 (D) 7

1️⃣1️⃣. Dipole moment of CS₂ is zero. Hence, the bond angle is:

🟥 (A) 90°

🟩 (B) 109.5°

🟦 (C) 120°

🟨 (D) 180°

1️⃣2️⃣. The volume of 0.2 M H₂SO₄ required for the neutralization of 10 cm³ of 0.1 M NaOH is:

🟥 (A) 2.5 cm³

🟩 (B) 5 cm³

🟦 (C) 10 cm³

🟨 (D) 15 cm³

1️⃣3️⃣. Photochemical reactions, which proceed only under the influence of light, are of the order:

🟥 (A) Zero

🟩 (B) First

🟦 (C) Second

🟨 (D) Third

1️⃣4️⃣. If a = b = c; and α = β = γ = 90°, then crystal structure is:

🟥 (A) Cubic

🟩 (B) Orthorhombic

🟦 (C) Tetragonal

🟨 (D) Hexagonal

1️⃣5️⃣. The most favourable conditions of temperature and pressure for oxidation of SO₂ into SO₃ are:

🟥 (A) High temperature and low pressure

🟩 (B) High temperature and high pressure

🟦 (C) Low temperature and low pressure

🟨 (D) Low temperature and high pressure

1️⃣6️⃣. With an increase in temperature, a system involving exothermic reaction will:

🟥 (A) Move in the forward direction

🟩 (B) Move in the reverse direction

🟦 (C) Remain at equilibrium

🟨 (D) None of these

1️⃣7️⃣. This one of the following pairs has the same number of molecules:

🟥 (A) 10 g H₂ and 10 g CH₄

🟩 (B) 10 g H₂ and 50 g CH₄

🟦 (C) 10 g H₂ and 80 g CH₄

🟨 (D) 10 g H₂ and 16 g CH₄

✨ Answers & Explanations ✨

1️⃣(A) Na⁺ and Mg²⁺

🟩 Reason: Both Na⁺ and Mg²⁺ have the same number of electrons (10 electrons), making them isoelectronic.

2️⃣(C) Violet

🟦 Reason: Violet light has the shortest wavelength in the visible spectrum.

3️⃣(A) Coulomb-metre

🟩 Reason: The SI unit of dipole moment is Coulomb-metre, which is a product of charge and distance.

4️⃣(C) 4.184 J

🟦 Reason: 1 calorie is equivalent to 4.184 joules.

5️⃣(B) 1 M

🟩 Reason: Molarity = moles/volume. 2 moles of NaOH in 2 dm³ gives a concentration of 1 M.

6️⃣(D) +6

🟨 Reason: In NaHSO₄, the oxidation number of sulfur is +6 as it is in the sulfate ion (SO₄²⁻).

7️⃣(D) Hydrogen bond

🟨 Reason: A hydrogen bond is a secondary bond, not a primary bond like ionic, covalent, or dative bonds.

8️⃣(C) Kp < Kc

🟦 Reason: Kp is related to Kc via the ideal gas law, and for this reaction, Kp will be less than Kc due to the change in the number of moles of gas.

9️⃣(B) Electrons

🟩 Reason: Conduction in metals is due to the movement of free electrons, which carry charge.

1️⃣0️⃣(D) 7

🟦 Reason: For a 5d orbital, n = 5, and l = 2. Thus, n+l = 5+2 = 7.

1️⃣1️⃣(D) 180°

🟨 Reason: CS₂ has a linear structure with a bond angle of 180°, and its dipole moment is zero because the two dipoles cancel out.

1️⃣2️⃣(B) 5 cm³

🟩 Reason: Using the formula M₁ V₁ = M₂ V₂ ​, we find that 5 cm³ of 0.2 M H₂SO₄ is required to neutralize 10 cm³ of 0.1 M NaOH.

1️⃣3️⃣(A) Zero

🟩 Reason: Photochemical reactions are typically of Zero order because the rate does not depend on the concentration.

1️⃣4️⃣(A) Cubic

🟩 Reason: When a = b = c and α = β = γ = 90°, the crystal structure is cubic.

1️⃣5️⃣(D) Low temperature and high pressure

🟨 Reason: The oxidation of SO₂ to SO₃ is favoured by low temperature and high pressure, according to Le Chatelier’s principle.

1️⃣6️⃣(B) Move in the reverse direction

🟩 Reason: For an exothermic reaction, increasing the temperature will shift the equilibrium to the left (reverse reaction), according to Le Chatelier's principle.

1️⃣7️⃣(D) 10 g H₂ and 16 g CH₄

🟨 Reason: Both H₂ and CH₄ have the same number of molecules (1 mole of H₂ and 1 mole of CH₄).

🔥🎯جونؔ ایلیا میری    بیاض سے📝🌈

💓💓💓

زندگی کس طرح بسر ہوگی

دل نہیں لگ رہا محبت میں

💓💓💓

علاج یہ ہے کہ مجبور کر دیا جاؤں

وگرنہ یوں تو کسی کی نہیں سنی میں نے

💓💓💓

سوچتا ہوں کہ اس کی یاد آخر

اب کسے رات بھر جگاتی ہے

💓💓💓

یارو کچھ تو ذکر کرو تم اس کی قیامت بانہوں کا

وہ جو سمٹتے ہوں گے ان میں وہ تو مر جاتے ہوں گے

💓💓💓

بن تمہارے کبھی نہیں آئی

کیا مری نیند بھی تمہاری ہے

💓💓💓

کس لیے دیکھتی ہو آئینہ

تم تو خود سے بھی خوب صورت ہو

💓💓💓

ہم کو یاروں نے یاد بھی نہ رکھا

جونؔ یاروں کے یار تھے ہم تو

💓💓💓

اس گلی نے یہ سن کے صبر کیا

جانے والے یہاں کے تھے ہی نہیں

💓💓💓

دل کی تکلیف کم نہیں کرتے

اب کوئی شکوہ ہم نہیں کرتے

💓💓💓

نیا اک رشتہ    پیدا کیوں کریں ہم

بچھڑنا ہے تو جھگڑا کیوں کریں ہم

💓💓💓

یاد اسے انتہائی کرتے ہیں

سو ہم اس کی برائی کرتے ہیں

💓💓💓

یوں جو تکتا ہے آسمان کو تو

کوئی رہتا ہے آسمان میں کیا

💓💓💓

اب نہیں کوئی بات خطرے کی

اب سبھی کو سبھی سے خطرہ ہے

💓💓💓

اے شخص میں تیری جستجو سے

بے زار نہیں ہوں تھک گیا ہوں

💓💓💓

کتنی دل کش ہو تم کتنا دلجو ہوں میں

کیا ستم ہے کہ ہم لوگ مر جائیں گے

💓💓💓

کیا کہا عشق جاودانی ہے!

آخری بار مل رہی ہو کیا

💓💓💓

اور تو کیا تھا بیچنے کے لئے

اپنی آنکھوں کے خواب بیچے ہیں

💓💓💓

تمہارا ہجر منا لوں اگر اجازت ہو

میں دل کسی سے لگا لوں اگر اجازت ہو

💓💓💓

کیا ستم ہے کہ اب تری صورت

غور کرنے پہ یاد آتی ہے

💓💓💓

کیسے کہیں کہ تجھ کو بھی ہم سے ہے واسطہ کوئی

تو نے تو ہم سے آج تک کوئی گلہ نہیں کیا

💓💓💓

مستقل بولتا ہی رہتا ہوں

کتنا خاموش ہوں میں اندر سے

💓💓💓

مجھے اب تم سے ڈر لگنے لگا ہے

تمہیں مجھ سے محبت ہو گئی کیا

💓💓💓

ساری دنیا کے غم ہمارے ہیں

اور ستم یہ کہ ہم تمہارے ہیں

💓💓💓

بہت نزدیک آتی جا رہی ہو

بچھڑنے کا ارادہ کر لیا کیا

💓💓💓

کون اس گھر کی دیکھ بھال کرے

روز اک چیز ٹوٹ جاتی ہے

💓💓💓

میری بانہوں میں بہکنے کی سزا بھی سن لے

اب بہت دیر میں آزاد کروں گا تجھ کو

💓💓💓

زندگی ایک فن ہے لمحوں کو

اپنے انداز سے گنوانے کا

💓💓💓

میں رہا عمر بھر جدا خود سے

یاد میں خود کو عمر بھر آیا

💓💓💓

اب مری کوئی زندگی ہی نہیں

اب بھی تم میری زندگی ہو کیا

💓💓💓

کتنے عیش سے رہتے ہوں گے کتنے اتراتے ہوں گے

جانے کیسے لوگ وہ ہوں گے جو اس کو بھاتے 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

💓💓💓

جان لیوا تھیں خواہشیں ورنہ

وصل سے انتظار اچھا تھا

💓💓💓

مجھ کو عادت ہے روٹھ جانے کی

آپ مجھ کو منا لیا کیجے

💓💓💓

اپنا رشتہ زمیں سے ہی رکھو

کچھ نہیں آسمان میں رکھا

💓💓💓

اپنے سب یار کام کر رہے ہیں

اور ہم ہیں کہ نام کر رہے ہیں

💓💓💓

میں جو ہوں جونؔ ایلیا ہوں جناب

اس کا بے حد لحاظ کیجئے گا

💓💓💓

ہاں ٹھیک ہے میں اپنی انا کا مریض ہوں

آخر مرے مزاج میں کیوں دخل دے کوئی

💓💓💓

میری ہر بات بے اثر ہی رہی

نقص ہے کچھ مرے بیان میں کیا

💓💓💓

ایک ہی تو ہوس رہی ہے ہمیں

اپنی حالت تباہ کی جائے

💓💓💓

آج مجھ کو بہت برا کہہ کر

آپ نے نام تو لیا میرا

💓💓💓

جرم میں ہم کمی کریں بھی تو کیوں

تم سزا بھی تو کم نہیں کرتے

💓💓💓

نہیں دنیا کو جب پروا ہماری

تو پھر دنیا کی پروا کیوں کریں ہم

💓💓💓

کام کی بات میں نے کی ہی نہیں

یہ مرا طور زندگی ہی نہیں

💓💓💓

اب تو ہر بات یاد رہتی ہے

غالباً میں کسی کو بھول گیا

💓💓💓

اک عجب حال ہے کہ اب اس کو

یاد کرنا بھی بے وفائی ہے

💓💓💓

کوئی مجھ تک پہنچ نہیں پاتا

اتنا آسان ہے پتا میرا

💓💓💓

کیا تکلف کریں یہ کہنے میں

جو بھی خوش ہے ہم اس سے جلتے ہیں

💓💓💓

میں بھی بہت عجیب ہوں۔اتنا عجیب ہوں کہ بس !!!۔

خود کو تباہ کر لیا ۔اور ملال بھی نہیں ۔!!!!۔

💓💓💓

کتنے ظالم ہیں جو یہ کہتے ہیں

توڑ لو پھول پھول چھوڑو مت۔

باغباں! ہم تو اس خیال کے ہیں

دیکھ لو پھول پھول توڑو مت۔

💓💓💓

مُسکرائے ہم اُس سے مِلتے وقت

رو نہ پڑتے اگر خُوشی ہوتی؟