1. The number of isomers of hexane are
👉 Hexane (C₆H₁₄) is an alkane having 5 structural isomers due to different branching patterns i.e n Hexane, 2 Methylpentane, 3 Methylpentane, 2,2 Dimethylbutane and 2,3 Dimethylbutane
2. Cycloalkenes have the general formula:
👉 Cycloalkenes have one double bond in the ring, reducing 2 hydrogens from CₙH₂ₙ (cycloalkanes) making its general formula CₙH₂ₙ₋₂. (Cycloalkanes → CₙH₂ₙ (like alkanes but cyclic).
3. The functional group in RCN is
👉 RCN or R–C≡N (where carbon is triple bonded to nitrogen) is the general formula nitrile (alkanenitrile). The CN group is called the nitrile or cyano group.
👉 Thioalcohols (SH), ethers (-O-), and thioethers (-S-) involve oxygen/sulfur, not a C≡N bond.
4. Propanone and propanal are
👉 Propanone (CH₃–CO–CH₃) → ketone. 👉 Propanal (CH₃–CH₂–CHO) → aldehyde. 👉 Same molecular formula (C₃H₆O) but different functional groups (aldehyde vs ketone). That makes them functional isomers.
5. The oxidation states of the elements of group VA is:
👉 Group VA elements (N, P, As, Sb, Bi) exhibit −3, +3, and +5 oxidation states.
🔥 Example: Nitrogen in NH₃ → −3.
🔥Phosphorus in PCl₃ → +3.
🔥Phosphorus in PCl₅ → +5.
6. Which of the following s block elements form normal oxide when burnt in air?
👉 Lithium forms normal oxide (Li₂O) when burnt in air, unlike Na, K, or Sr which form peroxides/superoxides.
7. In the equilibrium of dichromate ion(Cr₂O₇²⁻), the colours of CrO₄²⁻ and Cr₂O₇²⁻ are respectively:
👉 Chromate ion (CrO₄²⁻) is yellow, while dichromate (Cr₂O₇²⁻) is orange. 👉 So the correct option is c
8. The coordination number of Pt in [Pt(en)₃]Cl₄ is:
👉 en = ethylenediamine, a bidentate ligand (each en donates 2 lone pairs).
👉 In the Complex: [Pt(en)₃]Cl₄ → Pt is bonded to 3 en ligands.
👉 Each en contributes 2 donor atoms → total = 3 × 2 = 6 coordination sites giving coordination number 6.
9. The knocking of internal combustion engine can be reduced by the following petroleum process:
👉 Knocking is caused by premature ignition of fuel-air mixture.
👉 Reforming increases octane rating by converting straight chains into branched/aromatic hydrocarbons, reducing knocking thereby improving fuel quality. It converts straight-chain hydrocarbons into branched or aromatic ones → better combustion, less knocking.
👉 Refining and distillation separate components but don’t improve anti-knock quality.
👉 Resonance is unrelated to petroleum processing.
10. How many optical isomers are possible for HOOC(Br)CH–CH(OH)COOH?
👉 The molecule has two chiral centers, giving 2² = 4 optical isomers, with no meso form. Details
👉 The molecule is HOOC–CH(Br)–CH(OH)–COOH.
👉 It has two central carbons: one bonded to Br, the other bonded to OH. There are two chiral centers.
👉 C1 (CHBr): Attached to –COOH, –H, –Br, and –CH(OH)COOH → all different → chiral.
👉 C2 (CHOH): Attached to –COOH, –H, –OH, and –CH(Br)COOH → all different → chiral.
👉 Meso occurs if the molecule has an internal plane of symmetry.
👉 In this case, substituents (Br vs OH) are different → no meso form possible.
👉 General formula for Number of stereoisomers = = 2ⁿ, where n = number of chiral centers.
👉 Here, 2² = 4.
11. Which of the following pairs of compounds represent functional group isomerism?
👉 Each pair has the same molecular formula but different functional groups, so all represent functional group isomerism.
👉 Hence the correct choice is All of these.
🧠 Stepwise Reasoning
Functional group isomers → same molecular formula but different functional groups.
Propanone (CH₃–CO–CH₃) vs Propanal (CH₃–CH₂–CHO):
Both C₃H₆O, one is ketone, other aldehyde → functional group isomers.
Ethanol (C₂H₅OH) vs Dimethyl ether (CH₃–O–CH₃):
Both C₂H₆O, one is alcohol, other ether → functional group isomers.
Acetic acid (CH₃COOH) vs Methyl formate (HCOOCH₃):
Both C₂H₄O₂, one is carboxylic acid, other ester → functional group isomers.
👉 Hence all three pairs are functional group isomers.
12. Which of the following pairs of compounds represent positional isomerism?
🔎 1-butene/2-butene and iso propyl alcohol/1-propanol differ by position of double bond or OH group, so both represent positional isomerism.
🔎 🧠 Stepwise Reasoning
👉 Positional isomers → same carbon skeleton and functional group, but the position of the functional group or multiple bond differs.
👉 1-butene vs 2-butene:
Both are alkenes (C₄H₈).
Double bond position differs (C1 vs C2). ✅ Positional isomers.
👉 Iso-propyl alcohol (CH₃–CHOH–CH₃) vs 1-propanol (CH₃–CH₂–CH₂OH):
Both are alcohols (C₃H₈O).
OH group position differs (terminal vs middle carbon). ✅ Positional isomers.
👉 n-butane vs iso-butane:
Both are alkanes (C₄H₁₀).
Difference is in branching, not position of functional group. ❌ These are chain isomers, not positional.
✅ Correct Answer (d) Both a and b
13. Lucas Test is used to distinguish between:
🔎 Lucas test differentiates primary, secondary, and tertiary alcohols based on their reactivity with ZnCl₂/HCl.
🔎 🧠 Stepwise Reasoning
👉 Lucas reagent = ZnCl₂ + concentrated HCl.
👉 It tests the reactivity of alcohols with HCl to form alkyl chlorides.
🔎 Observation:
👉 Tertiary alcohols → react immediately (cloudy solution).
👉 Secondary alcohols → react within 5–10 minutes.
👉 Primary alcohols → no reaction at room temperature.
👉 Therefore, Lucas test is specifically used to distinguish primary, secondary, and tertiary alcohols.
14. General formula CₙH₂ₙ₋₂ represents:
🔎 The formula CₙH₂ₙ₋₂ applies to alkynes, cycloalkenes, and alkadienes, so all are correct.
🔎 🧠 Stepwise Reasoning
👉 Alkynes: General formula = CₙH₂ₙ₋₂ (for one triple bond). ✅
👉 Cycloalkenes: A cycloalkene has one ring + one double bond → loses 2 hydrogens compared to CₙH₂ₙ. Formula = CₙH₂ₙ₋₂.✅
👉 Alkadienes: For conjugated/cumulative dienes with two double bonds, formula also = CₙH₂ₙ₋₂. ✅
👉 Therefore, all three classes of compounds can be represented by CₙH₂ₙ₋₂.
15. The kinetics and molecularity of elimination bimolecular (E₂) reaction are respectively:
🔎 👉E₂ elimination is bimolecular: both substrate and base participate in the rate determining step. Hence, the reaction shows second order kinetics and has molecularity = 2.
🔎🧠 Stepwise Reasoning
📌 E₂ reaction = Elimination, bimolecular.
📌 In E₂, the rate determining step involves two species simultaneously:
⚡The substrate (alkyl halide)
⚡The base
📌 Therefore, the rate law depends on both concentrations: Rate = k [substrate][base]
📌 This makes the reaction second order kinetics.
📌 Since two species are involved in the slow step, the molecularity = 2.
16. The region of sphere which extends from 11 km to 50 km from Earth is known as:
👉 The stratosphere lies just above the troposphere, spanning from about 11 km to 50 km altitude. It contains the ozone layer, which absorbs harmful UV radiation.
🔎🧠 Stepwise Reasoning
📌Troposphere: Extends from surface up to ~11 km.
📌Stratosphere: Extends from ~11 km to ~50 km.
📌Mesosphere: Extends from ~50 km to ~85 km.
📌Thermosphere: Extends above ~85 km up to 600 km+.
👉 The region between 11 km and 50 km is the Stratosphere.
17. Clemmensen reduction is the conversion of aldehydes and ketones into:
👉 Clemmensen reduction removes the carbonyl oxygen and converts aldehydes/ketones into hydrocarbons (alkanes) using Zn(Hg)/HCl.
🔎🧠 Stepwise Reasoning
📌 Clemmensen reduction uses Zn(Hg) + concentrated HCl.
📌 It reduces the carbonyl group (C=O) of aldehydes and ketones.
📌 The oxygen is removed and the carbonyl carbon is converted into a –CH₂– group (for aldehydes) or –CH– group (for ketones).
📌 Final product = hydrocarbon (alkane).
👉 Example: CH₃COCH₃ (acetone) → CH₃–CH₂–CH₃ (propane).
18. Acetic acid is naturally found in:
👉 Acetic acid is the sour tasting acid naturally present in vinegar, whereas butter has butyric acid and bee stings have formic acid.
🔎🧠 Stepwise Reasoning
📌 Acetic acid (CH₃COOH) is the main component of vinegar, giving it its sour taste and pungent smell.
📌 Vinegar typically contains 4–8% acetic acid in water.
📌 Valerian root contains other organic acids and compounds, not acetic acid.
📌 Butter contains butyric acid (C₄H₈O₂), not acetic acid.
📌 Bee’s sting venom contains formic acid (HCOOH), not acetic acid.
19. An example of quaternary structure of protein is:
🔎 Hemoglobin exhibits quaternary structure because it consists of multiple polypeptide subunits (α₂ β₂) working together, unlike myoglobin or albumin which are single chain proteins.
🔎 🧠 Stepwise Reasoning
🔎 Protein structures:
📌 Primary: sequence of amino acids.
📌 Secondary: α helix, β sheet.
📌 Tertiary: 3D folding of a single polypeptide chain.
📌 Quaternary: association of two or more polypeptide chains into a functional protein.
🔎 Myoglobin: single polypeptide chain → tertiary structure only.
🔎 Albumin: also a single chain → tertiary structure only.
🔎 Globulin: general class of proteins, many are single chains.
🔎 👉 Hemoglobin: composed of 4 polypeptide chains (2α + 2β) → classic example of quaternary structure.
20. It is a three membered cyclic ether:
👉 Epoxides are three membered cyclic ethers with significant ring strain, making them highly reactive in organic chemistry.
🔎 🧠 Stepwise Reasoning
📌Diazonium salt: Not an ether, it’s an –N₂⁺ group attached to an aromatic ring.
📌Benzoquinone: A cyclic diketone, not an ether.
📌Ozonide: A five membered ring containing oxygen atoms, formed in ozonolysis.
📌Epoxide: A three membered cyclic ether (triangle shaped ring with one oxygen atom).
👉 Therefore, the correct option is Epoxide.
21. The coordination number of Cr in [Cr(H₂O)₄Cl₂]⁺ is:
👉 Four H₂O + two Cl⁻ ligands, all monodentate → CN = 6.
22. The number of unpaired electrons in gaseous species of Mn³⁺ and Co³⁺ respectively are:
👉 Mn = atomic number 25 → Mn³⁺ = [Ar] 3d⁴ → 4 unpaired electrons
👉 Co = atomic number 27 → Co³⁺ = [Ar] 3d⁶ → 3 unpaired electrons (high spin)
23. Which type of glycosidic linkage is present in maltose molecule?
👉 Maltose = glucose + glucose via α(1→4) glycosidic bond
👉 Both glucose units are in α-form → α-linkage
24. A zwitterion is:
👉 Zwitterion has both positive and negative charges but overall neutral
👉 Common in amino acids at isoelectric point
25. Aspirin is a pain reliever, its chemical name is:
👉 Aspirin = ester of salicylic acid and acetic acid → acetylsalicylic acid
👉 Ascorbic acid = Vitamin C
👉 Nicotinic acid = Vitamin B₃
26. Troposphere extends from planetary surface to bottom of ________?
👉 Troposphere is the lowest layer of atmosphere; it extends up to the base of the stratosphere (~12 km).
27. The atomic number of an element belonging to group IVA and 3rd period is:
👉 Group IVA = carbon family; 3rd period element is silicon, atomic number = 14.
28. A mixture of ZnCl₂ + conc. HCl is called
👉 Lucas reagent = A mixture of ZnCl₂ + conc. HCl, used to distinguish alcohols based on reactivity.
29. Select the incorrect statement regarding alkanes: (M)?
👉 Alkanes have sp³ hybridized carbon atoms, not sp² (which is for alkenes).
30. Fractional distillation of coal gives coke, coal tar, coal gas and:
👉 Ammonia liquor is a by-product of coal distillation, along with coke, coal tar, and coal gas.
31. An isomer of acetone is:
👉 Acetone = CH₃–CO–CH₃ (ketone)
👉 Acetaldehyde = CH₃–CHO (aldehyde)
👉 Both have formula C₃H₆O → functional isomers
32. Down the group atomic size increases due to:
👉 As you go down a group, more electron shells → inner electrons shield outer ones → atomic size increases
33. The most reactive molecule towards nucleophilic addition in the following is:
👉 Formaldehyde has no alkyl groups → least steric hindrance and strongest partial positive on carbonyl carbon → Most reactive to nucleophilic attack
34. In flame test, Apple green (Pale green) is given by
👉 In flame tests, barium salts produce a pale apple green flame, which is diagnostic for barium.
🔎 🧠 Stepwise Reasoning
📌 Flame test colors are due to excitation of electrons in metal ions.
📌 Barium salts give a characteristic apple green (pale green) flame.
📌 Beryllium does not impart a distinct flame color (too small, high ionization energy).
📌 Boron gives a bright green flame, but not the apple green shade typical of barium.
📌 Calcium gives a brick red flame, not green.
35. When an alkylbenzene reacts with acidified potassium permanganate, the alkyl group is oxidized to:
👉 Acidified KMnO₄ oxidizes the alkyl side chain of benzene completely to a carboxylic acid group (–COOH), regardless of chain length.
🔎 🧠 Stepwise Reasoning
📌 Alkylbenzenes (Ar–CH₃, Ar–CH₂R, etc.) undergo strong oxidation with acidified KMnO₄.
📌 Regardless of the length of the alkyl chain, the benzylic carbon (the carbon directly attached to the benzene ring) is oxidized completely.
📌 The final product is always benzoic acid (Ar–COOH) or substituted benzoic acids.
📌 Example: C₆H₅–CH₃ (KMnO₄/ H⁺) → C₆H₅–COOH
🔎 –CHO group (aldehyde) may appear as an intermediate but is further oxidized to –COOH.
🔎 –COO⁻ is the conjugate base of –COOH, but the product is written as the acid.
🔎 –CONH₂ (amide) is not formed in this reaction.
36. The distinct aroma and flavour of dairy products is due to:
👉 The characteristic flavour and aroma of dairy products, especially butter, comes from butyric acid.
🔎 🧠 Stepwise Reasoning
📌 Butyric acid (CH₃CH₂CH₂COOH):
📌 Found in butter and other dairy fats.
📌 Responsible for the characteristic aroma and flavour of dairy products.
📌 Also gives the rancid smell when butter spoils.
📌 Propionic acid: contributes to flavour in Swiss cheese but not the general dairy aroma.
📌 Acetic acid: gives vinegar its smell, not typical dairy flavour.
📌 Formic acid: pungent, found in ant venom, not related to dairy aroma.
37. Citric acid is used as a/an:
👉 Citric acid functions as a preservative, flavour enhancer, and acidity regulator, making option All of these correct.
🔎 🧠 Stepwise Reasoning
📌 Citric acid is a weak organic acid naturally found in citrus fruits. It has multiple uses in food and beverages:
📌 Preservative: Prevents microbial growth by lowering pH.
📌 Flavour enhancer: Adds a tangy, sour taste to foods and drinks.
📌 Acidity regulator: Maintains the desired pH in processed foods and beverages.
👉 Since citric acid serves all these roles, the most comprehensive answer is All of these.
38. The IUPAC name of salicylic acid is:
👉 Salicylic acid is benzoic acid with an –OH group at the ortho (2) position, hence 2-hydroxybenzoic acid.
🔎 🧠 Stepwise Reasoning
🔎 Salicylic acid has a benzene ring with:
📌 A –COOH group (carboxylic acid) at position 1.
📌 A –OH group (hydroxyl) at position 2 (ortho to the carboxyl group).
🔎 Therefore, its systematic IUPAC name is 2-hydroxybenzoic acid.
📌 If the –OH were at position 3, it would be 3-hydroxybenzoic acid (meta).
📌 If the –OH were at position 4, it would be 4-hydroxybenzoic acid (para).
📌 But salicylic acid specifically has the ortho (2 position) hydroxyl group.
39. The IUPAC name of sorbic acid is:
👉 Sorbic acid has a six carbon chain with double bonds at positions 2 and 4, hence Hexa 2,4-dienoic acid.
🔎 🧠 Stepwise Reasoning
📌 Sorbic acid is a naturally occurring unsaturated fatty acid used as a preservative.
📌 Its structure: CH₃–CH=CH–CH=CH–COOH.
📌 This is a six carbon chain (hex ) with two double bonds at positions 2 and 4.
📌 Therefore, the correct systematic name is Hexa 2,4-dienoic acid.
🔎 Option (b) Hexa 2,3-dienoic acid would mean double bonds at carbons 2 and 3, which is incorrect.
🔎 Option (c) Hex-2-enoic acid has only one double bond, not two.
40. Methylbenzene (toluene) is oxidized by acidified potassium permanganate into:
👉 Acidified KMnO₄ oxidizes the methyl group of methylbenzene completely to a carboxylic acid (benzoic acid).
🔎 🧠 Stepwise Reasoning
📌 Methylbenzene (C₆H₅–CH₃) has a benzylic –CH₃ group.
📌 Acidified KMnO₄ is a strong oxidizing agent.
📌 It oxidizes the entire alkyl side chain at the benzylic position, regardless of length, into a –COOH group.
📌 Thus, methylbenzene is converted into benzoic acid (C₆H₅–COOH).
🔎 Benzdioic acid (terephthalic acid) is not formed here.
🔎 Acetophenone (C₆H₅–CO–CH₃) is a ketone, not produced by oxidation of methylbenzene.
🔎 Benzaldehyde (C₆H₅–CHO) may appear as an intermediate but is further oxidized to benzoic acid.
Really helpful website and very well organised webpage masha allah
ReplyDelete