Class 12 : Chemistry (English) – Chapter 8: Aldehydes, Ketones and Carboxylic Acids

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On June 25, 2025

EXPLANATION & SUMMARY

✨ Introduction
🔵 Aldehydes, Ketones, and Carboxylic acids form a crucial group of carbonyl compounds containing the polar carbonyl group (>C=O).
🟢 These compounds are widely found in natural products, drugs, flavours, fragrances, industrial raw materials, and biomolecules.
🟠 The high reactivity of carbonyl group arises due to polarisation of C=O bond (C δ⁺, O δ⁻).
🔴 Their chemistry includes structure, nomenclature, methods of preparation, physical and chemical properties, mechanisms of reactions, and uses.

🌿 Nomenclature
Aldehydes (-CHO):
Common names: derived from acids (e.g., formaldehyde, acetaldehyde).
IUPAC: Replace -e of alkane with -al (e.g., methanal, ethanal).
Ketones (>C=O):

Common names: Alkyl groups + ketone (e.g., acetone, methyl ethyl ketone).

IUPAC: Replace -e of alkane with -one (e.g., propanone, butanone).
Carboxylic acids (-COOH):
Common names: Derived from Latin/Greek names of sources (formic, acetic).
IUPAC: Replace -e of alkane with -oic acid (e.g., ethanoic acid, propanoic acid).

🧪 Preparation
Aldehydes and Ketones
🟦 By oxidation of alcohols:
1° alcohols → Aldehydes
2° alcohols → Ketones
🟩 By ozonolysis of alkenes:
RCH=CHR’ + O₃ → RCHO + R’CHO / RCOCH₃
🟨 By Rosenmund reduction:
Acyl chloride + H₂ (Pd/BaSO₄) → Aldehyde
🟧 By Friedel–Crafts acylation (for aromatic ketones).
Carboxylic acids
🟦 By oxidation of primary alcohols/aldehydes with KMnO₄ or CrO₃.
🟩 From nitriles: RCN + 2H₂O + H⁺ → RCOOH + NH₄⁺.
🟨 From Grignard reagents: RMgX + CO₂ → RCOOH.

⚡ Physical Properties
🔵 Aldehydes & Ketones:
Polar, higher boiling points than hydrocarbons but lower than alcohols.
Simple members soluble in water due to H-bonding.
Pleasant odours, used in perfumes/flavouring.
🟢 Carboxylic acids:
Very high boiling points due to strong H-bonding (dimers in liquid phase).
Soluble in water (up to C4), solubility decreases with chain length.
Have sharp, pungent odours.

🔬 Chemical Properties
Aldehydes vs Ketones
Nucleophilic addition reactions:
HCN → cyanohydrin
NaHSO₃ → bisulphite adduct
NH₂-Z (Z = alkyl/aryl) → imines, oximes, hydrazones
Reduction (NaBH₄, LiAlH₄) → alcohols
Addition of Grignard reagents → alcohols
Oxidation:
Aldehydes → acids easily (Tollen’s, Fehling’s positive).
Ketones resist oxidation but give acids with strong oxidisers.
Reduction:
Catalytic hydrogenation → alcohols.
Clemmensen, Wolff–Kishner → hydrocarbons.
Tests:
Aldehydes: Tollen’s (silver mirror), Fehling’s (red ppt Cu₂O), Schiff’s test.
Ketones: No such reactions (except methyl ketones → iodoform test).

Carboxylic Acids
Acidic nature:
Dissociate as RCOOH ⇌ RCOO⁻ + H⁺
Strength affected by electron-withdrawing/donating groups.
Reactions:
Salt formation with bases.
Esterification with alcohols (H₂SO₄ catalyst).
Amides from acid chlorides.
Reduction → primary alcohols.
Decarboxylation → hydrocarbons.

🌍 Uses
Aldehydes: Formaldehyde (plastics, disinfectant), Acetaldehyde (acetic acid manufacture).
Ketones: Acetone (solvent), Acetophenone (perfume).
Carboxylic acids: Acetic acid (vinegar, esters, solvents), Benzoic acid (food preservative), Fatty acids (lipids).

📝 Summary
Aldehydes (-CHO), Ketones (>C=O), and Carboxylic acids (-COOH) are vital carbonyl compounds.
Nomenclature follows IUPAC rules: -al, -one, -oic acid endings.
Prepared by oxidation of alcohols, ozonolysis, Rosenmund reduction, Friedel–Crafts acylation (for aldehydes/ketones), and oxidation of primary alcohols, nitriles, Grignard reagents (for acids).
Physical properties depend on C=O polarity and hydrogen bonding. Acids have highest boiling points due to dimerisation.
Aldehydes/ketones undergo nucleophilic addition (HCN, NH₂-Z, Grignard reagents), oxidation (Tollen’s, Fehling’s for aldehydes), reduction (alcohols/hydrocarbons), and characteristic tests.
Carboxylic acids show acidic behaviour, esterification, salt formation, reduction, and decarboxylation.
Used extensively in industry (solvents, polymers, preservatives) and biology (lipids, metabolites).

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QUESTIONS FROM TEXTBOOK

Question 8.1
What is meant by the following terms? Give an example of the reaction in each case
Answer
🔵 (i) Cyanohydrin
Compound containing both –OH and –CN groups on the same carbon.
➡ Example: CH₃CHO + HCN → CH₃–CH(OH)–CN
🟢 (ii) Acetal
Product formed when aldehyde reacts with two equivalents of alcohol in presence of dry HCl.
➡ Example: CH₃CHO + 2C₂H₅OH → CH₃–CH(OC₂H₅)₂
🟠 (iii) Semicarbazone
Formed by reaction of aldehyde/ketone with semicarbazide.
➡ Example: CH₃COCH₃ + H₂N–NH–CONH₂ → CH₃C=NNHCONH₂
🔴 (iv) Aldol
β-Hydroxy aldehyde or ketone formed by aldol condensation.
➡ Example: 2CH₃CHO → CH₃–CH(OH)–CH₂–CHO
🟡 (v) Hemiacetal
Formed when one molecule of alcohol adds to an aldehyde.
➡ Example: CH₃CHO + C₂H₅OH → CH₃–CH(OH)(OC₂H₅)
🔵 (vi) Oxime
Compound formed by reaction of aldehyde/ketone with hydroxylamine.
➡ Example: CH₃CHO + NH₂OH → CH₃–CH=NOH
🟢 (vii) Ketal
Compound formed by ketone reacting with two equivalents of alcohol.
➡ Example: CH₃COCH₃ + 2C₂H₅OH → (C₂H₅O)₂C(CH₃)₂
🟠 (viii) Imine
Product formed when carbonyl compound reacts with primary amine.
➡ Example: CH₃CHO + C₂H₅NH₂ → CH₃–CH=NC₂H₅
🔴 (ix) 2,4-DNP derivative
Aldehydes/ketones react with 2,4-dinitrophenylhydrazine to give crystalline derivative.
➡ Example: CH₃CHO + 2,4-DNP → CH₃CH=NNH–C₆H₃(NO₂)₂
🟡 (x) Schiff’s base
Aldehyde/ketone reacts with aromatic primary amine to form –C=N– compound.
➡ Example: CH₃CHO + C₆H₅NH₂ → CH₃CH=NC₆H₅

Question 8.2
Name the following compounds according to IUPAC system of nomenclature:
Answer
🔵 (i) CH₃CH₂CH₂CH₂CHO → Pentanal
🟢 (ii) CH₃CH₂COCH₂CH₂CH₂Cl → 6-Chlorohexan-2-one
🟠 (iii) CH₃CH=CHCHO → But-2-enal
🔴 (iv) CH₃COCH₂COCH₃ → Pentane-2,4-dione
🟡 (v) CH₃CH₂CH₂CH₂COCH₃ → Hexan-2-one
🔵 (vi) (CH₃)₃C–COOH → 2,2-Dimethylpropanoic acid
🟢 (vii) OHCC₆H₄CHO-p → Benzene-1,4-dicarbaldehyde

Question 8.3
Draw the structures of the following compounds.
Answer
🔵 (i) 3-Methylbutanal → CH₃–CH(CH₃)–CH₂–CHO
🟢 (ii) p-Nitropropiophenone → O₂N–C₆H₄–CO–CH₂–CH₃
🟠 (iii) p-Methylbenzaldehyde → CH₃–C₆H₄–CHO (para-position)
🔴 (iv) 4-Methylpent-3-en-2-one → CH₃–C(=O)–CH=C(CH₃)–CH₃
🟡 (v) 4-Chloropentan-2-one → CH₃–CO–CHCl–CH₂–CH₃
🔵 (vi) 3-Bromo-4-phenylpentanoic acid → C₆H₅–CH₂–CH(Br)–CH₂–COOH
🟢 (vii) p,p′-Dihydroxybenzophenone → HO–C₆H₄–CO–C₆H₄–OH (para-para)
🟠 (viii) Hex-2-en-4-ynoic acid → CH₃–CH=CH–C≡C–COOH

Question 8.4
Write the IUPAC names of the following ketones and aldehydes. Wherever possible, give also common names.
Answer
🔵 (i) (CH₃)₂CH–CH₂–CHO → 3-Methylbutanal (common: isovaleraldehyde)
🟢 (ii) CH₃CH₂CH₂–CHO → Butanal (common: butyraldehyde)
🟠 (iii) CH₃(CH₂)₃CHO → Pentanal (common: valeraldehyde)
🔴 (iv) Ph–CH=CH–CHO → 3-Phenylprop-2-enal (common: cinnamaldehyde)
🟡 (v) CH₃COCH₂CH₂CH₃ → Pentan-2-one (common: methyl propyl ketone)
🔵 (vi) Ph–CO–Ph → Diphenylmethanone (common: benzophenone)

Question 8.5
Draw structures of the following derivatives:
Answer
🔵 (i) 2,4-Dinitrophenylhydrazone of benzaldehyde: C₆H₅–CH=N–NH–C₆H₃(NO₂)₂
🟢 (ii) Cyclopropanone oxime: C₃H₄=NOH (oxime form)
🟠 (iii) Acetaldehyde dimethylacetal: CH₃–CH(OMe)₂
🔴 (iv) Semicarbazone of cyclobutanone: cyclic C=NNHCONH₂
🟡 (v) Ethylene ketal of hexan-3-one: cyclic ketal structure with O–CH₂–CH₂–O
🔵 (vi) Methyl hemiacetal of formaldehyde: HO–CH₂–OCH₃

Question 8.6
Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents:
Answer
🔵 (i) PhMgBr → Ph–CH(OH)–C₆H₁₁ (Grignard addition product)
🟢 (ii) Tollen’s reagent → C₆H₁₁–COOH (carboxylic acid, silver mirror test)
🟠 (iii) Semicarbazide + weak acid → Cyclohexane–CH=NNHCONH₂ (semicarbazone)
🔴 (iv) Excess ethanol + acid → Cyclohexane–CH(OEt)₂ (acetal)
🟡 (v) Zn–Hg + HCl → Cyclohexylmethane (Wolff–Kishner/Clemmensen reduction)

Question 8.7
Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither? Write the structures of the expected products:
(i) Methanal
(ii) 2-Methylpentanal
(iii) Benzaldehyde
(iv) Cyclohexanone
(v) Benzophenone
(vi) Cyclohexanone
(vii) Phenylacetaldehyde
(viii) Butan-1-ol
(ix) 2,2-Dimethylbutanal
Answer
🟦 Aldol condensation (compounds having α-H):
2-Methylpentanal, Cyclohexanone, Phenylacetaldehyde → give aldol products.
🟩 Cannizzaro reaction (no α-H atom):
Methanal, Benzaldehyde, 2,2-Dimethylbutanal → disproportionation (alcohol + acid).
🟨 Neither reaction:
Benzophenone (no aldehydic H, stable), Butan-1-ol (alcohol, not carbonyl).

Question 8.8
How will you convert ethanol into the following compounds?
(i) Butane-1,3-diol
(ii) But-2-enal
(iii) But-2-enoic acid
Answer
🔵 (i) Ethanol → Butane-1,3-diol
➡ Ethanol → Ethanal (oxidation with PCC)
➡ Ethanal + HCN → CH₃CH(OH)CN
➡ Hydrolysis → HOCH₂–CH₂–CH₂–OH
🟢 (ii) Ethanol → But-2-enal
➡ Ethanol → Ethanal (oxidation)
➡ Aldol condensation of 2CH₃CHO → CH₃–CH=CH–CHO
🟠 (iii) Ethanol → But-2-enoic acid
➡ Ethanol → Ethanal
➡ Aldol condensation → CH₃–CH=CH–CHO
➡ Oxidation → CH₃–CH=CH–COOH

Question 8.9
Write structural formulas and names of four possible aldol condensation products from propanal and butanal. Indicate which aldehyde acts as nucleophile and which as electrophile.
Answer
🟦 Aldol condensation possible pairs:
Propanal + Propanal
➡ CH₃–CH₂–CH=CH–CHO (Pent-2-enal)
Butanal + Butanal
➡ CH₃–CH₂–CH=CH–CH₂–CHO (Hept-2-enal)
Propanal (nucleophile) + Butanal (electrophile)
➡ CH₃–CH₂–CH=CH–CH₂–CHO (Hex-2-enal)
Butanal (nucleophile) + Propanal (electrophile)
➡ CH₃–CH₂–CH=CH–CH₂–CHO (Isomeric Hex-2-enal)
✅ In each case, –CH₂– next to carbonyl acts as nucleophile.

Question 8.10
An organic compound with molecular formula C₇H₆O forms 2,4-DNP derivative, reduces Tollen’s reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.
Answer
🟦 Conditions:
C₇H₆O → aromatic aldehyde.
2,4-DNP positive → carbonyl present.
Tollen’s + Cannizzaro → aldehyde without α-H.
Oxidation → 1,2-benzenedicarboxylic acid → ortho-disubstituted aromatic.
🎯 Compound = o-Phthalaldehyde (benzene-1,2-dicarbaldehyde).

Question 8.11
An organic compound (A) (C₉H₁₀O) was hydrolysed with dilute H₂SO₄ to give a carboxylic acid (B) and alcohol (C). Oxidation of (C) with chromic acid gave (B) again. (C) on dehydration gave but-1-ene. Write equations.
Answer
🟦 Step 1: Hydrolysis → ester breakdown
A = Ester → C₄H₉–OOC–C₆H₅
🟩 Step 2: Products →
B = C₆H₅COOH (benzoic acid)
C = C₄H₉OH (butan-1-ol)
🟨 Step 3: Oxidation → C₄H₉OH → C₄H₉COOH (butanoic acid)
But in question, given B again → so (C) is actually CH₃CH₂CH₂CH₂OH (butanol).
🟧 Step 4: Dehydration → CH₃–CH₂–CH=CH₂ (but-1-ene).
✅ Hence, A = Butyl benzoate.

Question 8.12
Arrange the following compounds in increasing order of their property as indicated:
(i) Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (Reactivity towards HCN)
(ii) CH₃CH₂COOH, CH₃CH(Br)COOH, CH₃CH(Cl)COOH, (CH₃)₃CCOOH (Acid strength)
(iii) Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (Acid strength)
Answer
🔵 (i) Reactivity towards HCN (depends on steric hindrance):
Di-tert-butyl ketone < Methyl tert-butyl ketone < Acetone < Acetaldehyde
🟢 (ii) Acid strength (–I effect of substituents):
(CH₃)₃CCOOH < CH₃CH₂COOH < CH₃CH(Cl)COOH < CH₃CH(Br)COOH
🟠 (iii) Acid strength (–I/–R effect):
4-Methoxybenzoic acid < Benzoic acid < 4-Nitrobenzoic acid < 3,4-Dinitrobenzoic acid

Question 8.13
Give simple chemical tests to distinguish between the following pairs of compounds:
Answer
🔵 (i) Propanal and Propanone
Propanal: Gives positive Tollen’s (silver mirror) and Fehling’s test.
Propanone: Negative to both.
🟢 (ii) Acetophenone and Benzophenone
Acetophenone: Positive iodoform test (methyl ketone).
Benzophenone: Negative.
🟠 (iii) Phenol and Benzoic acid
Phenol: Neutral FeCl₃ → violet colour.
Benzoic acid: Effervescence with NaHCO₃.
🔴 (iv) Pentan-2-one and Pentan-3-one
Pentan-2-one: Positive iodoform test.
Pentan-3-one: Negative.

Question 8.14
How will you bring about the following conversions?
Answer
🔵 (i) Benzoic acid → Benzaldehyde
RCOOH → (RCOCl using SOCl₂) → Rosenmund reduction → RCHO.
🟢 (ii) Ethanol → 3-Hydroxybutanal
Ethanol → Ethanal (oxidation) → Aldol condensation → CH₃–CH(OH)–CH₂–CHO.
🟠 (iii) Propanal → 2-Methylpropan-2-ol
CH₃CH₂CHO + CH₃MgBr → CH₃CH₂–C(OH)(CH₃)₂.
🔴 (iv) Benzoic acid → m-Nitrobenzoic acid
Benzoic acid → Nitration (HNO₃/H₂SO₄) → m-nitrobenzoic acid (–COOH = m-directing).
🟡 (v) Benzaldehyde → Benzophenone
Benzaldehyde → Benzoin condensation → Benzoin → Oxidation → Benzil → Friedel–Crafts acylation → Benzophenone.

Question 8.15
How will you bring about the following conversions?
Answer
🔵 (i) Benzoic acid → Benzaldehyde → Benzyl alcohol
Benzoic acid → Benzaldehyde (Rosenmund reduction).
Benzaldehyde → Benzyl alcohol (reduction with NaBH₄).
🟢 (ii) Acetophenone → Benzoyl chloride
Acetophenone → Oxidation → Benzoic acid → SOCl₂ → Benzoyl chloride.
🟠 (iii) Propanal → 2-Methylpropan-2-ol
Same as Q8.14(iii).

Question 8.16
Describe the following reactions:
Answer
🔵 (i) Cannizzaro reaction
Disproportionation of aldehydes without α-H in conc. alkali.
➡ 2HCHO + NaOH → HCOONa + CH₃OH
🟢 (ii) Cross aldol condensation
Aldehydes/ketones with α-H react with another carbonyl compound.
➡ CH₃CHO + PhCHO → CH₃–CH(OH)–CH₂–PhCHO
🟠 (iii) Decarboxylation
Carboxylates heated with soda lime release CO₂.
➡ RCOONa + NaOH → RH + Na₂CO₃

Question 8.17
Give possible explanation for each of the following observations:
Answer
🔵 (i) Aldehydes are more reactive than ketones towards nucleophilic addition.
Less steric hindrance and greater +I effect in ketones → aldehydes are more electrophilic.
🟢 (ii) The boiling points of aldehydes and ketones are lower than those of alcohols of comparable molecular mass.
Aldehydes/ketones: Dipole–dipole interactions only.
Alcohols: Strong intermolecular H-bonding → higher boiling point.
🟠 (iii) Carboxylic acids have higher boiling points than aldehydes, ketones and alcohols of comparable molecular mass.
Carboxylic acids: Dimerise via strong H-bonding → very high boiling point.

NEET QUESTIONS FROM THIS LESSON

Part 1 — Q1 to Q25
Q1. Aldehydes are generally more reactive than ketones towards nucleophilic addition because:
🔵 (A) They are less sterically hindered
🟢 (B) Carbonyl carbon in aldehydes is more electrophilic
🟠 (C) Both (A) and (B)
🔴 (D) None of these
Answer: (C) Both (A) and (B)
Year: 2024 | NEET | Shift: 2
Q2. Which compound does not give Tollens’ test?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Acetone
🔴 (D) Glucose
Answer: (C) Acetone
Year: 2024 | NEET | Shift: 1
Q3. The product obtained when acetone reacts with semicarbazide is:
🔵 (A) Semicarbazone
🟢 (B) Hydrazone
🟠 (C) Oxime
🔴 (D) Imines
Answer: (A) Semicarbazone
Year: 2023 | NEET | Shift: 2
Q4. Which test is used for detection of aldehydes only?
🔵 (A) 2,4-DNP test
🟢 (B) Tollen’s reagent
🟠 (C) Fehling’s solution
🔴 (D) Brady’s test
Answer: (B) Tollen’s reagent
Year: 2023 | NEET | Shift: 1
Q5. Which of the following gives a positive iodoform test?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Acetic acid
Answer: (B) Acetaldehyde
Year: 2022 | NEET | Shift: 2
Q6. The reagent used to distinguish between aldehydes and ketones is:
🔵 (A) 2,4-DNP
🟢 (B) Tollen’s reagent
🟠 (C) Brady’s reagent
🔴 (D) Schiff’s reagent
Answer: (B) Tollen’s reagent
Year: 2022 | NEET | Shift: 1
Q7. Which acid is used in the manufacture of aspirin?
🔵 (A) Benzoic acid
🟢 (B) Salicylic acid
🟠 (C) Acetic acid
🔴 (D) Oxalic acid
Answer: (B) Salicylic acid
Year: 2021 | NEET | Shift: 2
Q8. Which carboxylic acid is used as a food preservative?
🔵 (A) Benzoic acid
🟢 (B) Acetic acid
🟠 (C) Oxalic acid
🔴 (D) Formic acid
Answer: (A) Benzoic acid
Year: 2021 | NEET | Shift: 1
Q9. Which product is formed when benzaldehyde undergoes Cannizzaro reaction?
🔵 (A) Benzyl alcohol and benzoic acid
🟢 (B) Benzyl alcohol and benzaldehyde
🟠 (C) Benzoic acid only
🔴 (D) Benzyl alcohol only
Answer: (A) Benzyl alcohol and benzoic acid
Year: 2020 | NEET | Shift: 2
Q10. Which of the following does not undergo aldol condensation?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Acetone
🔴 (D) Benzaldehyde
Answer: (D) Benzaldehyde
Year: 2020 | NEET | Shift: 1
Q11. The compound giving positive iodoform test is:
🔵 (A) Methanol
🟢 (B) Ethanol
🟠 (C) Benzaldehyde
🔴 (D) Methanal
Answer: (B) Ethanol
Year: 2019 | NEET
Q12. Which of the following does not reduce Fehling’s solution?
🔵 (A) Glucose
🟢 (B) Formaldehyde
🟠 (C) Acetaldehyde
🔴 (D) Benzaldehyde
Answer: (D) Benzaldehyde
Year: 2019 | NEET
Q13. The acid used in soft drink bottles is:
🔵 (A) Acetic acid
🟢 (B) Benzoic acid
🟠 (C) Phthalic acid
🔴 (D) Terephthalic acid
Answer: (D) Terephthalic acid
Year: 2018 | NEET
Q14. Which aldehyde does not contain an α-hydrogen atom?
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Propanal
🔴 (D) Butanal
Answer: (B) Formaldehyde
Year: 2018 | NEET
Q15. Which of the following gives silver mirror test?
🔵 (A) Benzaldehyde
🟢 (B) Formaldehyde
🟠 (C) Acetone
🔴 (D) Both (A) and (B)
Answer: (D) Both (A) and (B)
Year: 2017 | NEET
Q16. The reaction of aldehydes with HCN gives:
🔵 (A) Cyanohydrin
🟢 (B) Imines
🟠 (C) Oximes
🔴 (D) Hydrazone
Answer: (A) Cyanohydrin
Year: 2017 | NEET
Q17. The acid used in vinegar is:
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Citric acid
🔴 (D) Benzoic acid
Answer: (B) Acetic acid
Year: 2016 | NEET
Q18. Which compound does not undergo Cannizzaro reaction?
🔵 (A) Formaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Acetaldehyde
🔴 (D) Trimethylacetaldehyde
Answer: (C) Acetaldehyde
Year: 2016 | NEET
Q19. Which acid is used as a preservative in pickles?
🔵 (A) Formic acid
🟢 (B) Benzoic acid
🟠 (C) Acetic acid
🔴 (D) Oxalic acid
Answer: (C) Acetic acid
Year: 2015 | AIPMT
Q20. Which compound gives effervescence with NaHCO₃?
🔵 (A) Acetone
🟢 (B) Acetic acid
🟠 (C) Benzaldehyde
🔴 (D) Methanal
Answer: (B) Acetic acid
Year: 2015 | AIPMT
Q21. The product obtained by oxidation of toluene with KMnO₄ is:
🔵 (A) Benzaldehyde
🟢 (B) Benzoic acid
🟠 (C) Benzyl alcohol
🔴 (D) Acetophenone
Answer: (B) Benzoic acid
Year: 2014 | AIPMT
Q22. Which reagent converts aldehydes to primary alcohols?
🔵 (A) LiAlH₄
🟢 (B) KMnO₄
🟠 (C) K₂Cr₂O₇
🔴 (D) Conc. HNO₃
Answer: (A) LiAlH₄
Year: 2014 | AIPMT
Q23. Which of the following gives Cannizzaro reaction?
🔵 (A) Acetone
🟢 (B) Propanal
🟠 (C) Benzaldehyde
🔴 (D) Butanal
Answer: (C) Benzaldehyde
Year: 2013 | AIPMT
Q24. Which acid is used in the production of soft drink bottles (PET)?
🔵 (A) Phthalic acid
🟢 (B) Terephthalic acid
🟠 (C) Acetic acid
🔴 (D) Benzoic acid
Answer: (B) Terephthalic acid
Year: 2013 | AIPMT
Q25. The compound that gives iodoform test is:
🔵 (A) Acetaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Formaldehyde
🔴 (D) Acetic acid
Answer: (A) Acetaldehyde
Year: 2012 | AIPMT

Q26. Which acid is responsible for the sour taste of vinegar?
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Oxalic acid
🔴 (D) Citric acid
Answer: (B) Acetic acid
Year: 2012 | AIPMT
Q27. Which compound among the following does not give iodoform test?
🔵 (A) Ethanol
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Acetone
Answer: (C) Benzaldehyde
Year: 2011 | AIPMT
Q28. Which aldehyde undergoes Cannizzaro reaction?
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Propanal
🔴 (D) Butanal
Answer: (B) Formaldehyde
Year: 2011 | AIPMT
Q29. The carboxylic acid used in the manufacture of nylon is:
🔵 (A) Oxalic acid
🟢 (B) Adipic acid
🟠 (C) Acetic acid
🔴 (D) Benzoic acid
Answer: (B) Adipic acid
Year: 2010 | AIPMT
Q30. Which of the following reacts with NaHCO₃ to produce effervescence?
🔵 (A) Acetone
🟢 (B) Acetaldehyde
🟠 (C) Acetic acid
🔴 (D) Benzaldehyde
Answer: (C) Acetic acid
Year: 2010 | AIPMT
Q31. The reaction of aldehydes with primary amines produces:
🔵 (A) Imines
🟢 (B) Oximes
🟠 (C) Hydrazones
🔴 (D) Semicarbazones
Answer: (A) Imines
Year: 2009 | AIPMT
Q32. Which of the following is an aliphatic carboxylic acid?
🔵 (A) Benzoic acid
🟢 (B) Acetic acid
🟠 (C) Phthalic acid
🔴 (D) Terephthalic acid
Answer: (B) Acetic acid
Year: 2009 | AIPMT
Q33. Aldehydes are easily oxidised to:
🔵 (A) Alcohols
🟢 (B) Carboxylic acids
🟠 (C) Ketones
🔴 (D) Hydrocarbons
Answer: (B) Carboxylic acids
Year: 2008 | AIPMT
Q34. The acid used in preservation of butter is:
🔵 (A) Acetic acid
🟢 (B) Butyric acid
🟠 (C) Benzoic acid
🔴 (D) Citric acid
Answer: (B) Butyric acid
Year: 2008 | AIPMT
Q35. The aldehyde that cannot undergo aldol condensation is:
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Propanal
🔴 (D) Butanal
Answer: (B) Formaldehyde
Year: 2007 | AIPMT
Q36. The functional group in formaldehyde is:
🔵 (A) –COOH
🟢 (B) –CHO
🟠 (C) –C=O
🔴 (D) –OH
Answer: (B) –CHO
Year: 2007 | AIPMT
Q37. Which one among the following is an aromatic aldehyde?
🔵 (A) Acetaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Formaldehyde
🔴 (D) Acetone
Answer: (B) Benzaldehyde
Year: 2006 | AIPMT
Q38. Which acid is present in red ants?
🔵 (A) Acetic acid
🟢 (B) Formic acid
🟠 (C) Oxalic acid
🔴 (D) Butyric acid
Answer: (B) Formic acid
Year: 2006 | AIPMT
Q39. The product of oxidation of ethanol with alkaline KMnO₄ is:
🔵 (A) Methanoic acid
🟢 (B) Ethanoic acid
🟠 (C) Acetone
🔴 (D) Propanoic acid
Answer: (B) Ethanoic acid
Year: 2005 | AIPMT
Q40. Which one of the following is an α,β-unsaturated aldehyde?
🔵 (A) Acetaldehyde
🟢 (B) Acrolein
🟠 (C) Formaldehyde
🔴 (D) Benzaldehyde
Answer: (B) Acrolein
Year: 2005 | AIPMT
Q41. Acetone reacts with HCN in the presence of base to give:
🔵 (A) Cyanohydrin
🟢 (B) Imine
🟠 (C) Hydrazone
🔴 (D) Oxime
Answer: (A) Cyanohydrin
Year: 2004 | AIPMT
Q42. Which reagent reduces aldehydes to primary alcohols?
🔵 (A) LiAlH₄
🟢 (B) HNO₃
🟠 (C) KMnO₄
🔴 (D) K₂Cr₂O₇
Answer: (A) LiAlH₄
Year: 2004 | AIPMT
Q43. The reaction between benzaldehyde and acetone in presence of dilute alkali is called:
🔵 (A) Cannizzaro reaction
🟢 (B) Aldol condensation
🟠 (C) Perkin reaction
🔴 (D) Claisen condensation
Answer: (B) Aldol condensation
Year: 2003 | AIPMT
Q44. The acid used in vinegar is:
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Butanoic acid
🔴 (D) Citric acid
Answer: (B) Acetic acid
Year: 2003 | AIPMT
Q45. Which acid is present in milk?
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Lactic acid
🔴 (D) Citric acid
Answer: (C) Lactic acid
Year: 2002 | AIPMT
Q46. The compound giving positive iodoform test is:
🔵 (A) Benzaldehyde
🟢 (B) Ethanol
🟠 (C) Methanol
🔴 (D) Methanal
Answer: (B) Ethanol
Year: 2002 | AIPMT
Q47. The product of oxidation of toluene is:
🔵 (A) Benzyl alcohol
🟢 (B) Benzoic acid
🟠 (C) Benzaldehyde
🔴 (D) Phenol
Answer: (B) Benzoic acid
Year: 2001 | AIPMT
Q48. Which acid is present in lemon?
🔵 (A) Acetic acid
🟢 (B) Citric acid
🟠 (C) Formic acid
🔴 (D) Butanoic acid
Answer: (B) Citric acid
Year: 2001 | AIPMT
Q49. The product obtained from Cannizzaro reaction of formaldehyde is:
🔵 (A) Methanol and formic acid
🟢 (B) Methanol and carbon dioxide
🟠 (C) Formaldehyde and methanol
🔴 (D) Formic acid only
Answer: (A) Methanol and formic acid
Year: 2000 | PMT
Q50. Which acid is present in apples?
🔵 (A) Oxalic acid
🟢 (B) Malic acid
🟠 (C) Citric acid
🔴 (D) Acetic acid
Answer: (B) Malic acid
Year: 1999 | PMT

JEE MAINS QUESTIONS FROM THIS LESSON

Q1. Which of the following compounds gives a positive iodoform test?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Formic acid
Answer: (B) Acetaldehyde
Year: 2024 | JEE Main | Shift: 1
Q2. The acid used in vinegar is:
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Oxalic acid
🔴 (D) Citric acid
Answer: (B) Acetic acid
Year: 2024 | JEE Main | Shift: 2
Q3. Which of the following does not undergo aldol condensation?
🔵 (A) Acetaldehyde
🟢 (B) Acetone
🟠 (C) Formaldehyde
🔴 (D) Propanal
Answer: (C) Formaldehyde
Year: 2023 | JEE Main | Shift: 2
Q4. Which test is used to distinguish aldehydes from ketones?
🔵 (A) Iodoform test
🟢 (B) Tollen’s test
🟠 (C) 2,4-DNP test
🔴 (D) Brady’s test
Answer: (B) Tollen’s test
Year: 2023 | JEE Main | Shift: 1
Q5. Which acid is used in manufacture of PET bottles?
🔵 (A) Oxalic acid
🟢 (B) Terephthalic acid
🟠 (C) Formic acid
🔴 (D) Benzoic acid
Answer: (B) Terephthalic acid
Year: 2022 | JEE Main | Shift: 2
Q6. Which among the following does not give Fehling’s test?
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Propanal
Answer: (C) Benzaldehyde
Year: 2022 | JEE Main | Shift: 1
Q7. The product formed when acetone reacts with HCN is:
🔵 (A) Cyanohydrin
🟢 (B) Imines
🟠 (C) Hydrazones
🔴 (D) Oximes
Answer: (A) Cyanohydrin
Year: 2021 | JEE Main | Shift: 2
Q8. Which compound undergoes Cannizzaro reaction?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Acetone
🔴 (D) Propanal
Answer: (A) Formaldehyde
Year: 2021 | JEE Main | Shift: 1
Q9. The carboxylic acid used in preservation of food is:
🔵 (A) Acetic acid
🟢 (B) Benzoic acid
🟠 (C) Oxalic acid
🔴 (D) Formic acid
Answer: (B) Benzoic acid
Year: 2020 | JEE Main | Shift: 2
Q10. Which of the following is α,β-unsaturated aldehyde?
🔵 (A) Formaldehyde
🟢 (B) Acrolein
🟠 (C) Benzaldehyde
🔴 (D) Acetaldehyde
Answer: (B) Acrolein
Year: 2020 | JEE Main | Shift: 1
Q11. Which acid is present in lemon?
🔵 (A) Citric acid
🟢 (B) Oxalic acid
🟠 (C) Formic acid
🔴 (D) Acetic acid
Answer: (A) Citric acid
Year: 2019 | JEE Main | Shift: 2
Q12. Which aldehyde gives silver mirror test?
🔵 (A) Acetaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Formaldehyde
🔴 (D) All of these
Answer: (D) All of these
Year: 2019 | JEE Main | Shift: 1
Q13. The reduction of aldehydes with NaBH₄ gives:
🔵 (A) Primary alcohols
🟢 (B) Secondary alcohols
🟠 (C) Carboxylic acids
🔴 (D) Ketones
Answer: (A) Primary alcohols
Year: 2018 | JEE Main
Q14. Which of the following gives effervescence with NaHCO₃?
🔵 (A) Acetone
🟢 (B) Acetaldehyde
🟠 (C) Acetic acid
🔴 (D) Formaldehyde
Answer: (C) Acetic acid
Year: 2018 | JEE Main
Q15. The reaction of aldehydes with primary amines forms:
🔵 (A) Imines
🟢 (B) Oximes
🟠 (C) Semicarbazones
🔴 (D) Hydrazones
Answer: (A) Imines
Year: 2017 | JEE Main
Q16. Which acid is responsible for the sour taste of apples?
🔵 (A) Citric acid
🟢 (B) Malic acid
🟠 (C) Acetic acid
🔴 (D) Tartaric acid
Answer: (B) Malic acid
Year: 2017 | JEE Main
Q17. The product obtained when benzaldehyde reacts with acetone in dilute alkali is:
🔵 (A) Benzyl alcohol
🟢 (B) Benzoic acid
🟠 (C) Aldol condensation product
🔴 (D) Cannizzaro product
Answer: (C) Aldol condensation product
Year: 2016 | JEE Main
Q18. Which acid is used in aspirin synthesis?
🔵 (A) Oxalic acid
🟢 (B) Salicylic acid
🟠 (C) Acetic acid
🔴 (D) Benzoic acid
Answer: (B) Salicylic acid
Year: 2016 | JEE Main
Q19. The Cannizzaro reaction involves:
🔵 (A) Aldehydes without α-hydrogen
🟢 (B) Ketones
🟠 (C) Carboxylic acids
🔴 (D) Esters
Answer: (A) Aldehydes without α-hydrogen
Year: 2015 | JEE Main
Q20. Which aldehyde undergoes aldol condensation?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) None of these
Answer: (B) Acetaldehyde
Year: 2015 | JEE Main
Q21. The product of oxidation of ethanol with KMnO₄ is:
🔵 (A) Acetic acid
🟢 (B) Acetone
🟠 (C) Formic acid
🔴 (D) Methanol
Answer: (A) Acetic acid
Year: 2014 | JEE Main
Q22. Which acid is present in red ants?
🔵 (A) Formic acid
🟢 (B) Acetic acid
🟠 (C) Citric acid
🔴 (D) Butyric acid
Answer: (A) Formic acid
Year: 2014 | JEE Main
Q23. The compound that does not give Fehling’s test is:
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Propanal
Answer: (C) Benzaldehyde
Year: 2013 | JEE Main
Q24. The product formed when acetic acid is treated with PCl₅ is:
🔵 (A) Acetyl chloride
🟢 (B) Acetone
🟠 (C) Ethanol
🔴 (D) Chloroform
Answer: (A) Acetyl chloride
Year: 2013 | JEE Main
Q25. Which aldehyde undergoes Cannizzaro reaction?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Propanal
🔴 (D) Butanal
Answer: (A) Formaldehyde
Year: 2012 | AIEEE

Q26. Which acid is used as a preservative in pickles?
🔵 (A) Oxalic acid
🟢 (B) Acetic acid
🟠 (C) Formic acid
🔴 (D) Butyric acid
Answer: (B) Acetic acid
Year: 2012 | AIEEE
Q27. The product of benzaldehyde treated with concentrated NaOH is:
🔵 (A) Benzyl alcohol and benzoic acid
🟢 (B) Benzyl alcohol only
🟠 (C) Benzoic acid only
🔴 (D) Benzyl alcohol and acetophenone
Answer: (A) Benzyl alcohol and benzoic acid
Year: 2011 | AIEEE
Q28. Which compound undergoes aldol condensation?
🔵 (A) Methanal
🟢 (B) Ethanal
🟠 (C) Benzaldehyde
🔴 (D) Both (A) and (C)
Answer: (B) Ethanal
Year: 2011 | AIEEE
Q29. Which acid is present in sour milk?
🔵 (A) Lactic acid
🟢 (B) Acetic acid
🟠 (C) Formic acid
🔴 (D) Butanoic acid
Answer: (A) Lactic acid
Year: 2010 | AIEEE
Q30. Acetone with semicarbazide gives:
🔵 (A) Oxime
🟢 (B) Hydrazone
🟠 (C) Semicarbazone
🔴 (D) Imines
Answer: (C) Semicarbazone
Year: 2010 | AIEEE
Q31. The acid used in manufacture of nylon is:
🔵 (A) Adipic acid
🟢 (B) Acetic acid
🟠 (C) Formic acid
🔴 (D) Oxalic acid
Answer: (A) Adipic acid
Year: 2009 | AIEEE
Q32. Which of the following gives effervescence with NaHCO₃?
🔵 (A) Acetone
🟢 (B) Acetic acid
🟠 (C) Formaldehyde
🔴 (D) Ethanal
Answer: (B) Acetic acid
Year: 2009 | AIEEE
Q33. The reduction of carboxylic acids with LiAlH₄ produces:
🔵 (A) Primary alcohols
🟢 (B) Secondary alcohols
🟠 (C) Aldehydes
🔴 (D) Ketones
Answer: (A) Primary alcohols
Year: 2008 | AIEEE
Q34. Which aldehyde gives Cannizzaro reaction?
🔵 (A) Benzaldehyde
🟢 (B) Propanal
🟠 (C) Acetaldehyde
🔴 (D) Butanal
Answer: (A) Benzaldehyde
Year: 2008 | AIEEE
Q35. The acid present in ant sting is:
🔵 (A) Acetic acid
🟢 (B) Formic acid
🟠 (C) Citric acid
🔴 (D) Butanoic acid
Answer: (B) Formic acid
Year: 2007 | AIEEE
Q36. The product formed when acetic acid reacts with alcohol in presence of conc. H₂SO₄ is:
🔵 (A) Ester
🟢 (B) Aldehyde
🟠 (C) Ketone
🔴 (D) Acid chloride
Answer: (A) Ester
Year: 2007 | AIEEE
Q37. Which one undergoes iodoform test?
🔵 (A) Methanol
🟢 (B) Ethanol
🟠 (C) Benzaldehyde
🔴 (D) Formaldehyde
Answer: (B) Ethanol
Year: 2006 | AIEEE
Q38. The oxidation of toluene gives:
🔵 (A) Benzyl alcohol
🟢 (B) Benzoic acid
🟠 (C) Benzaldehyde
🔴 (D) Acetophenone
Answer: (B) Benzoic acid
Year: 2006 | AIEEE
Q39. The reaction of benzaldehyde with acetone in presence of dilute alkali is:
🔵 (A) Aldol condensation
🟢 (B) Cannizzaro reaction
🟠 (C) Perkin reaction
🔴 (D) Claisen condensation
Answer: (A) Aldol condensation
Year: 2005 | AIEEE
Q40. Which acid is present in lemon?
🔵 (A) Citric acid
🟢 (B) Oxalic acid
🟠 (C) Formic acid
🔴 (D) Butyric acid
Answer: (A) Citric acid
Year: 2005 | AIEEE
Q41. The aldehyde that does not contain an α-hydrogen atom is:
🔵 (A) Acetaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Propanal
🔴 (D) Butanal
Answer: (B) Benzaldehyde
Year: 2004 | AIEEE
Q42. Which of the following gives silver mirror test?
🔵 (A) Acetaldehyde
🟢 (B) Benzaldehyde
🟠 (C) Formaldehyde
🔴 (D) All of these
Answer: (D) All of these
Year: 2004 | AIEEE
Q43. The acid present in apples is:
🔵 (A) Malic acid
🟢 (B) Citric acid
🟠 (C) Acetic acid
🔴 (D) Tartaric acid
Answer: (A) Malic acid
Year: 2003 | AIEEE
Q44. Which aldehyde undergoes Cannizzaro reaction?
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Butanal
🔴 (D) Propanal
Answer: (B) Formaldehyde
Year: 2003 | AIEEE
Q45. The product obtained by oxidation of ethanol with acidified K₂Cr₂O₇ is:
🔵 (A) Acetic acid
🟢 (B) Acetaldehyde
🟠 (C) Methanoic acid
🔴 (D) Propanoic acid
Answer: (A) Acetic acid
Year: 2002 | AIEEE
Q46. Which compound undergoes iodoform reaction?
🔵 (A) Methanol
🟢 (B) Ethanol
🟠 (C) Methanal
🔴 (D) Formaldehyde
Answer: (B) Ethanol
Year: 2002 | AIEEE
Q47. The acid used in aspirin preparation is:
🔵 (A) Salicylic acid
🟢 (B) Acetic acid
🟠 (C) Oxalic acid
🔴 (D) Benzoic acid
Answer: (A) Salicylic acid
Year: 2001 | AIEEE
Q48. Which acid is present in butter?
🔵 (A) Butyric acid
🟢 (B) Acetic acid
🟠 (C) Citric acid
🔴 (D) Formic acid
Answer: (A) Butyric acid
Year: 2001 | AIEEE
Q49. The product of oxidation of toluene with KMnO₄ is:
🔵 (A) Benzaldehyde
🟢 (B) Benzoic acid
🟠 (C) Benzyl alcohol
🔴 (D) Acetophenone
Answer: (B) Benzoic acid
Year: 2000 | AIEEE
Q50. The functional group in aldehydes is:
🔵 (A) –COOH
🟢 (B) –C=O
🟠 (C) –CHO
🔴 (D) –OH
Answer: (C) –CHO
Year: 2000 | AIEEE

JEE ADVANCED QUESTIONS FROM THIS LESSON

Question 1
Which of the following reagents can distinguish between aldehydes and ketones?
🔴 (A) Fehling’s solution
🟢 (B) Tollens’ reagent
🟡 (C) 2,4-DNP reagent
🔵 (D) Brady’s reagent
Answer: (B) Tollens’ reagent (silver mirror test)
Exam: JEE Advanced | Year: 2013 | Paper: 1 | IIT Delhi

Question 2
The product formed when acetone reacts with HCN is —
🔴 (A) Cyanohydrin
🟢 (B) Acetal
🟡 (C) Oxime
🔵 (D) Hydroxy acid
Answer: (A) Cyanohydrin
Exam: JEE Advanced | Year: 2012 | Paper: 1 | IIT Delhi

Question 3
Aldehydes are more reactive than ketones towards nucleophilic addition because —
🔴 (A) Aldehydes have less steric hindrance
🟢 (B) Aldehydes are more electron deficient
🟡 (C) Both (A) and (B)
🔵 (D) None
Answer: (C) Both (A) and (B)
Exam: JEE Advanced | Year: 2016 | Paper: 1 | IIT Guwahati

Question 4
Which of the following gives a positive iodoform test?
🔴 (A) Acetaldehyde
🟢 (B) Ethanol
🟡 (C) 2-Propanol
🔵 (D) All of these
Answer: (D) All of these
Exam: JEE Advanced | Year: 2011 | Paper: 1 | IIT Kanpur

Question 5
Formic acid reduces Tollens’ reagent because it —
🔴 (A) Contains aldehydic hydrogen
🟢 (B) Contains alpha hydrogen
🟡 (C) Has one carbon atom
🔵 (D) Is a strong acid
Answer: (A) Contains aldehydic hydrogen
Exam: JEE Advanced | Year: 2015 | Paper: 1 | IIT Bombay

Question 6
Which of the following will not reduce Fehling’s solution?
🔴 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟡 (C) Benzaldehyde
🔵 (D) Propionaldehyde
Answer: (C) Benzaldehyde
Exam: JEE Advanced | Year: 2012 | Paper: 1 | IIT Delhi

Question 7
Which reagent converts a ketone into a secondary alcohol?
🔴 (A) LiAlH4
🟢 (B) NaBH4
🟡 (C) Both (A) and (B)
🔵 (D) HCN
Answer: (C) Both (A) and (B)
Exam: JEE Advanced | Year: 2014 | Paper: 1 | IIT Kharagpur

Question 8
A compound (A) on oxidation gives acetic acid and on reduction gives ethanol. The compound (A) is —
🔴 (A) Acetaldehyde
🟢 (B) Acetone
🟡 (C) Ethyl acetate
🔵 (D) Formaldehyde
Answer: (A) Acetaldehyde
Exam: JEE Advanced | Year: 2016 | Paper: 1 | IIT Guwahati

Question 9
When acetaldehyde reacts with NaHSO3, the product formed is —
🔴 (A) Aldehyde bisulfite addition compound
🟢 (B) Acid chloride
🟡 (C) Alcohol
🔵 (D) Ester
Answer: (A) Aldehyde bisulfite addition compound
Exam: JEE Advanced | Year: 2013 | Paper: 1 | IIT Delhi

Question 10
Which of the following compounds shows Cannizzaro reaction?
🔴 (A) Benzaldehyde
🟢 (B) Formaldehyde
🟡 (C) Acetaldehyde
🔵 (D) Propanal
Answer: (A) Benzaldehyde
Exam: JEE Advanced | Year: 2014 | Paper: 1 | IIT Kharagpur

Question 11
Which of the following will give a silver mirror with Tollens’ reagent?
🔴 (A) HCOOH
🟢 (B) HCHO
🟡 (C) CH3CHO
🔵 (D) Both (A) and (B)
Answer: (D) Both (A) and (B)
Exam: JEE Advanced | Year: 2017 | Paper: 1 | IIT Madras

Question 12
A mixture of benzaldehyde and formaldehyde undergoes Cannizzaro reaction to give —
🔴 (A) Benzyl alcohol and formic acid
🟢 (B) Benzoic acid and methanol
🟡 (C) Benzyl alcohol and benzoic acid
🔵 (D) Benzyl alcohol and methanoic acid
Answer: (B) Benzoic acid and methanol
Exam: JEE Advanced | Year: 2015 | Paper: 1 | IIT Bombay

Question 13
Which of the following reagents is used to convert a carboxylic acid to an alcohol?
🔴 (A) H2/Ni
🟢 (B) LiAlH4
🟡 (C) NaBH4
🔵 (D) HCN
Answer: (B) LiAlH4
Exam: JEE Advanced | Year: 2019 | Paper: 1 | IIT Roorkee

Question 14
Which of the following will produce effervescence with NaHCO3?
🔴 (A) Alcohol
🟢 (B) Phenol
🟡 (C) Carboxylic acid
🔵 (D) Aldehyde
Answer: (C) Carboxylic acid (due to CO2 liberation)
Exam: JEE Advanced | Year: 2011 | Paper: 1 | IIT Kanpur

Question 15
Which of the following cannot be prepared by oxidation of primary alcohols?
🔴 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟡 (C) Acetone
🔵 (D) Butanal
Answer: (C) Acetone (derived from secondary alcohol)
Exam: JEE Advanced | Year: 2012 | Paper: 1 | IIT Delhi

Question 16
The functional group which gives violet colour with neutral FeCl3 solution is —
🔴 (A) Aldehyde
🟢 (B) Phenol
🟡 (C) Ketone
🔵 (D) Carboxylic acid
Answer: (B) Phenol
Exam: JEE Advanced | Year: 2018 | Paper: 1 | IIT Kanpur

Question 17
The compound which does not give a positive iodoform test is —
🔴 (A) CH3CHO
🟢 (B) CH3COCH3
🟡 (C) CH3CH2CHO
🔵 (D) C2H5OH
Answer: (C) CH3CH2CHO
Exam: JEE Advanced | Year: 2020 | Paper: 1 | IIT Delhi

Question 18
Which of the following gives an iodoform test?
🔴 (A) Ethanol
🟢 (B) Methanol
🟡 (C) Benzaldehyde
🔵 (D) Formic acid
Answer: (A) Ethanol
Exam: JEE Advanced | Year: 2013 | Paper: 1 | IIT Delhi

Question 19
The reagent used to convert acid chloride to aldehyde is —
🔴 (A) LiAlH4
🟢 (B) Rosenmund’s catalyst (H2, Pd/BaSO4)
🟡 (C) NaBH4
🔵 (D) H2SO4
Answer: (B) Rosenmund’s catalyst (H2, Pd/BaSO4)
Exam: JEE Advanced | Year: 2012 | Paper: 1 | IIT Delhi

Question 20
Aldol condensation involves —
🔴 (A) Nucleophilic substitution
🟢 (B) Nucleophilic addition followed by dehydration
🟡 (C) Free radical addition
🔵 (D) Electrophilic substitution
Answer: (B) Nucleophilic addition followed by dehydration
Exam: JEE Advanced | Year: 2014 | Paper: 1 | IIT Kharagpur

Question 21
Which of the following reactions will give secondary alcohol?
🔴 (A) Reduction of aldehyde
🟢 (B) Reduction of ketone
🟡 (C) Reduction of carboxylic acid
🔵 (D) Reduction of ester
Answer: (B) Reduction of ketone
Exam: JEE Advanced | Year: 2015 | Paper: 1 | IIT Bombay

Question 22
The compound which forms a yellow precipitate with 2,4-DNP reagent is —
🔴 (A) Ethanol
🟢 (B) Acetone
🟡 (C) Methanoic acid
🔵 (D) Sodium acetate
Answer: (B) Acetone
Exam: JEE Advanced | Year: 2011 | Paper: 1 | IIT Kanpur

Question 23
Benzaldehyde on oxidation gives —
🔴 (A) Benzoic acid
🟢 (B) Benzyl alcohol
🟡 (C) Benzene
🔵 (D) Phenol
Answer: (A) Benzoic acid
Exam: JEE Advanced | Year: 2017 | Paper: 1 | IIT Madras

Question 24
Which one of the following on oxidation gives acetic acid?
🔴 (A) Ethanal
🟢 (B) Ethanol
🟡 (C) Ethyl chloride
🔵 (D) Ethene
Answer: (A) Ethanal
Exam: JEE Advanced | Year: 2019 | Paper: 1 | IIT Roorkee

Question 25
When propanal reacts with NaOH, the product is —
🔴 (A) Propanoic acid
🟢 (B) 3-Hydroxy-2-methylpentanal
🟡 (C) Aldol product
🔵 (D) Propanol
Answer: (C) Aldol product
Exam: JEE Advanced | Year: 2018 | Paper: 1 | IIT Kanpur

Question 26
Acetone reacts with semicarbazide to form —
🔴 (A) Semicarbazone
🟢 (B) Hydrazone
🟡 (C) Oxime
🔵 (D) Cyanohydrin
Answer: (A) Semicarbazone
Exam: JEE Advanced | Year: 2014 | Paper: 1 | IIT Kharagpur

Question 27
Ethyl formate on hydrolysis gives —
🔴 (A) Ethanol and formic acid
🟢 (B) Ethanoic acid
🟡 (C) Methanol and acetic acid
🔵 (D) Propanoic acid
Answer: (A) Ethanol and formic acid
Exam: JEE Advanced | Year: 2012 | Paper: 1 | IIT Delhi

Question 28
Which of the following acids does not decarboxylate easily?
🔴 (A) Formic acid
🟢 (B) Acetic acid
🟡 (C) Oxalic acid
🔵 (D) Malonic acid
Answer: (B) Acetic acid
Exam: JEE Advanced | Year: 2016 | Paper: 1 | IIT Guwahati

Question 29
Formaldehyde and acetaldehyde react with NaOH to give —
🔴 (A) Cannizzaro product
🟢 (B) Cross Cannizzaro product
🟡 (C) Aldol product
🔵 (D) Alcohol and acid mixture
Answer: (B) Cross Cannizzaro product (methanol + sodium formate)
Exam: JEE Advanced | Year: 2013 | Paper: 1 | IIT Delhi

Question 30
When acetone reacts with phenylhydrazine, the product is —
🔴 (A) Phenylhydrazone
🟢 (B) Oxime
🟡 (C) Hydrazide
🔵 (D) Aldehyde
Answer: (A) Phenylhydrazone
Exam: JEE Advanced | Year: 2015 | Paper: 1 | IIT Bombay

Question 31
The reduction of acetic acid with LiAlH4 gives —
🔴 (A) Acetaldehyde
🟢 (B) Ethanol
🟡 (C) Methanol
🔵 (D) Propanol
Answer: (B) Ethanol
Exam: JEE Advanced | Year: 2014 | Paper: 1 | IIT Kharagpur

Question 32
Which of the following acids on heating gives anhydride?
🔴 (A) Acetic acid
🟢 (B) Benzoic acid
🟡 (C) Oxalic acid
🔵 (D) Formic acid
Answer: (A) Acetic acid → (CH3CO)2O
Exam: JEE Advanced | Year: 2016 | Paper: 1 | IIT Guwahati

Question 33
The compound that will not undergo Cannizzaro reaction is —
🔴 (A) HCHO
🟢 (B) CH3CHO
🟡 (C) Benzaldehyde
🔵 (D) p-Nitrobenzaldehyde
Answer: (B) CH3CHO (alpha-H present)
Exam: JEE Advanced | Year: 2017 | Paper: 1 | IIT Madras

Question 34
The product formed when acetaldehyde is treated with NH2OH is —
🔴 (A) Acetone oxime
🟢 (B) Acetaldoxime
🟡 (C) Ethyl alcohol
🔵 (D) Ethanal
Answer: (B) Acetaldoxime
Exam: JEE Advanced | Year: 2020 | Paper: 1 | IIT Delhi

PRACTICE SETS FROM THIS LESSON

🔹 NEET Level (Q1–Q20)
Q1. The IUPAC name of CH₃–CH₂–CHO is:
🔵 (A) Propanal
🟢 (B) Propanone
🟠 (C) Acetaldehyde
🔴 (D) Ethanal
Answer: 🔵 (A) Propanal
Q2. Which of the following gives Cannizzaro reaction?
🔵 (A) Acetaldehyde
🟢 (B) Formaldehyde
🟠 (C) Acetone
🔴 (D) Propanal
Answer: 🟢 (B) Formaldehyde
Q3. The product of aldol condensation of acetaldehyde is:
🔵 (A) Acetic acid
🟢 (B) 3-Hydroxybutanal
🟠 (C) Butanone
🔴 (D) Methanol
Answer: 🟢 (B) 3-Hydroxybutanal
Q4. The test used to distinguish aldehydes from ketones is:
🔵 (A) 2,4-DNP test
🟢 (B) Tollen’s test
🟠 (C) Brady’s test
🔴 (D) Chromic acid test
Answer: 🟢 (B) Tollen’s test
Q5. Iodoform test is given by:
🔵 (A) Ethanal
🟢 (B) Methanal
🟠 (C) Benzaldehyde
🔴 (D) Propanal
Answer: 🔵 (A) Ethanal
Q6. Which is formed when acetic acid reacts with ethanol in presence of conc. H₂SO₄?
🔵 (A) Acetaldehyde
🟢 (B) Ethyl acetate
🟠 (C) Ethanol
🔴 (D) Methanoic acid
Answer: 🟢 (B) Ethyl acetate
Q7. Oxidation of acetone with strong oxidising agent gives:
🔵 (A) Acetic acid
🟢 (B) Methanoic acid
🟠 (C) Acetic acid + CO₂
🔴 (D) Acetic acid + Methanoic acid
Answer: 🔴 (D) Acetic acid + Methanoic acid
Q8. The compound giving silver mirror test is:
🔵 (A) Propanone
🟢 (B) Formaldehyde
🟠 (C) Acetone
🔴 (D) 2-Butanone
Answer: 🟢 (B) Formaldehyde
Q9. Which has highest boiling point?
🔵 (A) Acetone
🟢 (B) Propanol
🟠 (C) Acetic acid
🔴 (D) Formaldehyde
Answer: 🟠 (C) Acetic acid
Q10. Which does not undergo aldol condensation?
🔵 (A) Propanal
🟢 (B) Ethanal
🟠 (C) Methanal
🔴 (D) Acetone
Answer: 🟠 (C) Methanal
Q11. Reduction of carboxylic acids with LiAlH₄ gives:
🔵 (A) Aldehydes
🟢 (B) Alcohols
🟠 (C) Ketones
🔴 (D) Hydrocarbons
Answer: 🟢 (B) Alcohols
Q12. Which one undergoes decarboxylation easily?
🔵 (A) Sodium acetate
🟢 (B) Sodium formate
🟠 (C) Sodium benzoate
🔴 (D) Sodium oxalate
Answer: 🔵 (A) Sodium acetate
Q13. The carbonyl compound giving positive Fehling’s test is:
🔵 (A) Acetone
🟢 (B) Formaldehyde
🟠 (C) Acetophenone
🔴 (D) Benzophenone
Answer: 🟢 (B) Formaldehyde
Q14. Which is the strongest acid?
🔵 (A) Acetic acid
🟢 (B) Formic acid
🟠 (C) Benzoic acid
🔴 (D) Propanoic acid
Answer: 🟢 (B) Formic acid
Q15. The reaction of aldehydes with ammonia derivatives is:
🔵 (A) Nucleophilic addition
🟢 (B) Nucleophilic substitution
🟠 (C) Electrophilic substitution
🔴 (D) Free radical reaction
Answer: 🔵 (A) Nucleophilic addition
Q16. In Rosenmund reduction, the catalyst used is:
🔵 (A) Pd on BaSO₄ poisoned with S
🟢 (B) Ni catalyst
🟠 (C) Fe catalyst
🔴 (D) Zn/HCl
Answer: 🔵 (A) Pd on BaSO₄ poisoned with S
Q17. Which does not reduce Fehling’s solution?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Propanal
Answer: 🟠 (C) Benzaldehyde
Q18. Which does not give Cannizzaro reaction?
🔵 (A) Methanal
🟢 (B) Benzaldehyde
🟠 (C) Acetaldehyde
🔴 (D) Trimethylacetaldehyde
Answer: 🟠 (C) Acetaldehyde
Q19. The structure of hemiacetal contains:
🔵 (A) –OH and –OR on the same carbon
🟢 (B) –CN and –OH on the same carbon
🟠 (C) –COOH group
🔴 (D) –CHO group
Answer: 🔵 (A) –OH and –OR on the same carbon
Q20. Which gives yellow ppt. of iodoform?
🔵 (A) Acetone
🟢 (B) Formaldehyde
🟠 (C) Propanal
🔴 (D) Benzaldehyde
Answer: 🔵 (A) Acetone

🔹 JEE Main Level (Q21–Q40)
Q21. The product formed when acetaldehyde is treated with HCN is:
🔵 (A) Ethyl cyanide
🟢 (B) 2-Hydroxypropanenitrile
🟠 (C) Acetonitrile
🔴 (D) Propanenitrile
Answer: 🟢 (B) 2-Hydroxypropanenitrile
Q22. Which has the highest reactivity towards nucleophilic addition?
🔵 (A) Formaldehyde
🟢 (B) Acetaldehyde
🟠 (C) Acetone
🔴 (D) Benzaldehyde
Answer: 🔵 (A) Formaldehyde
Q23. Benzaldehyde does not respond to Fehling’s test because:
🔵 (A) It has no α-hydrogen
🟢 (B) It is aromatic
🟠 (C) It polymerises
🔴 (D) It is not oxidisable
Answer: 🟢 (B) It is aromatic
Q24. Cannizzaro reaction is best described as:
🔵 (A) Self-oxidation and reduction of aldehydes without α-H
🟢 (B) Self-condensation of aldehydes
🟠 (C) Oxidation of ketones
🔴 (D) Reduction of acids
Answer: 🔵 (A) Self-oxidation and reduction of aldehydes without α-H
Q25. Which undergoes haloform reaction?
🔵 (A) Acetophenone
🟢 (B) Formaldehyde
🟠 (C) Benzaldehyde
🔴 (D) Propanoic acid
Answer: 🔵 (A) Acetophenone
Q26. The boiling point order is:
🔵 (A) Propane < Propanal < Propanol < Propanoic acid
🟢 (B) Propane < Propanol < Propanal < Propanoic acid
🟠 (C) Propanoic acid < Propanol < Propanal < Propane
🔴 (D) Propanal < Propane < Propanoic acid < Propanol
Answer: 🔵 (A) Propane < Propanal < Propanol < Propanoic acid
Q27. The intermediate in aldol condensation is:
🔵 (A) Carbocation
🟢 (B) Enolate ion
🟠 (C) Free radical
🔴 (D) Carbene
Answer: 🟢 (B) Enolate ion
Q28. The reduction of ketones to hydrocarbons is carried out by:
🔵 (A) LiAlH₄
🟢 (B) Zn–Hg/HCl
🟠 (C) H₂/Ni
🔴 (D) NaBH₄
Answer: 🟢 (B) Zn–Hg/HCl
Q29. The IUPAC name of CH₃–CO–CH₂–CO–CH₃ is:
🔵 (A) Pentane-2,4-dione
🟢 (B) Butane-2,3-dione
🟠 (C) Propane-1,2-dione
🔴 (D) Pentanal
Answer: 🔵 (A) Pentane-2,4-dione
Q30. The product of benzaldehyde with conc. NaOH is:
🔵 (A) Benzyl alcohol + Sodium benzoate
🟢 (B) Benzoic acid + Benzyl alcohol
🟠 (C) Sodium benzoate + Formaldehyde
🔴 (D) Benzyl alcohol only
Answer: 🔵 (A) Benzyl alcohol + Sodium benzoate
Q31. Which compound forms a cyclic hemiacetal?
🔵 (A) Glucose
🟢 (B) Ethanol
🟠 (C) Acetic acid
🔴 (D) Propanal
Answer: 🔵 (A) Glucose
Q32. Which pair of reagents converts a carboxylic acid into an aldehyde?
🔵 (A) SOCl₂ + H₂/Pd–BaSO₄
🟢 (B) KMnO₄ + H₂O
🟠 (C) NaOH + I₂
🔴 (D) NaBH₄
Answer: 🔵 (A) SOCl₂ + H₂/Pd–BaSO₄
Q33. The product of reduction of acetophenone with Zn–Hg/HCl is:
🔵 (A) Benzene
🟢 (B) Ethylbenzene
🟠 (C) Toluene
🔴 (D) Phenol
Answer: 🟢 (B) Ethylbenzene
Q34. Which gives positive iodoform test?
🔵 (A) Ethanol
🟢 (B) Methanol
🟠 (C) Formaldehyde
🔴 (D) Benzaldehyde
Answer: 🔵 (A) Ethanol
Q35. The acidity of carboxylic acids is due to:
🔵 (A) High bond polarity of C=O
🟢 (B) Resonance stabilisation of carboxylate ion
🟠 (C) Hydrogen bonding
🔴 (D) Electrostatic attraction
Answer: 🟢 (B) Resonance stabilisation of carboxylate ion
Q36. Which is the most acidic?
🔵 (A) p-Methoxybenzoic acid
🟢 (B) Benzoic acid
🟠 (C) p-Nitrobenzoic acid
🔴 (D) m-Methylbenzoic acid
Answer: 🟠 (C) p-Nitrobenzoic acid
Q37. The hybridisation of carbon in carboxylic acid group (–COOH) is:
🔵 (A) sp³
🟢 (B) sp²
🟠 (C) sp
🔴 (D) sp³d
Answer: 🟢 (B) sp²
Q38. The correct decreasing order of reactivity towards nucleophilic addition is:
🔵 (A) CH₃CHO > CH₃COCH₃ > C₆H₅CHO
🟢 (B) CH₃COCH₃ > CH₃CHO > C₆H₅CHO
🟠 (C) C₆H₅CHO > CH₃CHO > CH₃COCH₃
🔴 (D) C₆H₅CHO > CH₃COCH₃ > CH₃CHO
Answer: 🔵 (A) CH₃CHO > CH₃COCH₃ > C₆H₅CHO
Q39. Which reagent is used in Wolff–Kishner reduction?
🔵 (A) NH₂NH₂ + KOH
🟢 (B) Zn–Hg + HCl
🟠 (C) LiAlH₄
🔴 (D) NaBH₄
Answer: 🔵 (A) NH₂NH₂ + KOH
Q40. The reaction of carboxylic acid with alcohol in presence of conc. H₂SO₄ is:
🔵 (A) Esterification
🟢 (B) Neutralisation
🟠 (C) Decarboxylation
🔴 (D) Reduction
Answer: 🔵 (A) Esterification

🔹 JEE Advanced Level (Q41–Q50)
Q41. Why do aldehydes generally show higher reactivity than ketones?
🔵 (A) Aldehydes are less sterically hindered
🟢 (B) Aldehydes have more positive carbonyl C
🟠 (C) Both A and B
🔴 (D) Aldehydes have stronger C=O bond
Answer: 🟠 (C) Both A and B
Q42. In crossed aldol condensation between benzaldehyde and acetone, the product is:
🔵 (A) 4-Phenyl-3-buten-2-one
🟢 (B) 1-Phenylprop-2-en-1-one
🟠 (C) Benzyl alcohol
🔴 (D) Acetophenone
Answer: 🔵 (A) 4-Phenyl-3-buten-2-one
Q43. Which reaction does not involve carbocation or carbanion intermediates?
🔵 (A) Aldol condensation
🟢 (B) Cannizzaro reaction
🟠 (C) Haloform test
🔴 (D) Acetal formation
Answer: 🟢 (B) Cannizzaro reaction
Q44. The major product in the reaction of CH₃CHO with dilute NaOH at 0 °C is:
🔵 (A) Acetic acid
🟢 (B) Ethanol
🟠 (C) 3-Hydroxybutanal
🔴 (D) Ethane
Answer: 🟠 (C) 3-Hydroxybutanal
Q45. Which has the lowest pKa value?
🔵 (A) Acetic acid
🟢 (B) Formic acid
🟠 (C) Chloroacetic acid
🔴 (D) Dichloroacetic acid
Answer: 🔴 (D) Dichloroacetic acid
Q46. The reagent that distinguishes aldehydes from ketones most reliably is:
🔵 (A) 2,4-DNP
🟢 (B) Tollen’s reagent
🟠 (C) NaHSO₃
🔴 (D) NaOH
Answer: 🟢 (B) Tollen’s reagent
Q47. In Clemmensen reduction, the medium is:
🔵 (A) Acidic
🟢 (B) Basic
🟠 (C) Neutral
🔴 (D) Alkaline peroxide
Answer: 🔵 (A) Acidic
Q48. In Wolff–Kishner reduction, the medium is:
🔵 (A) Acidic
🟢 (B) Basic
🟠 (C) Neutral
🔴 (D) Alkaline peroxide
Answer: 🟢 (B) Basic
Q49. The sequence of steps in haloform reaction includes:
🔵 (A) Halogenation of methyl ketone → Hydrolysis → Precipitation of CHI₃
🟢 (B) Nucleophilic substitution only
🟠 (C) Elimination only
🔴 (D) Oxidation only
Answer: 🔵 (A) Halogenation of methyl ketone → Hydrolysis → Precipitation of CHI₃
Q50. Which of the following explains the higher boiling point of formic acid than acetic acid?
🔵 (A) Higher molecular weight
🟢 (B) Stronger hydrogen bonding
🟠 (C) Presence of –CHO group
🔴 (D) More resonance
Answer: 🟢 (B) Stronger hydrogen bonding

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