Class 12 Aldehydes Ketones and Carboxylic Acids MCQ

Class 12 Aldehydes Ketones and Carboxylic Acids MCQ

Class 12 Chemistry : Aldehydes, Ketones and Carboxylic Acids

MCQs + Fill in the Blanks + Assertion Reason + Match + Very Short Questions

SECTION A: MCQs (Multiple Choice Questions)

1. The functional group present in aldehydes is:

A) –COOH
B) –CHO
C) –OH
D) –CO–

Answer: B) –CHO

2. The carbon atom of the carbonyl group is:

A) sp hybridised
B) sp² hybridised
C) sp³ hybridised
D) dsp² hybridised

Answer: B) sp² hybridised

3. The bond angle around carbonyl carbon is approximately:

A) 90°
B) 109.5°
C) 120°
D) 180°

Answer: C) 120°

4. The most reactive carbonyl compound towards nucleophilic addition is:

A) Acetone
B) Ethanal
C) Benzophenone
D) Formaldehyde

Answer: D) Formaldehyde

5. Aldehydes are more reactive than ketones because:

A) They have higher molecular mass
B) They have less steric hindrance
C) They contain two alkyl groups
D) They are non-polar

Answer: B) They have less steric hindrance

6. Which reagent converts aldehydes into alcohols?

A) NaBH₄
B) KMnO₄
C) NaOH
D) HCN

Answer: A) NaBH₄

7. Rosenmund reduction converts:

A) Alcohol into aldehyde
B) Acid chloride into aldehyde
C) Ketone into alcohol
D) Acid into alcohol

Answer: B) Acid chloride into aldehyde

8. Stephen reaction involves conversion of:

A) Nitrile into aldehyde
B) Alcohol into ketone
C) Acid into ester
D) Alkene into acid

Answer: A) Nitrile into aldehyde

9. Etard reaction converts:

A) Benzene into benzaldehyde
B) Toluene into benzaldehyde
C) Benzaldehyde into benzoic acid
D) Alcohol into aldehyde

Answer: B) Toluene into benzaldehyde

10. Friedel–Crafts acylation produces:

A) Alcohol
B) Ketone
C) Aldehyde
D) Acid

Answer: B) Ketone

11. The reagent used in Tollens’ test is:

A) Fehling solution
B) Ammoniacal AgNO₃
C) NaHCO₃
D) H₂SO₄

Answer: B) Ammoniacal AgNO₃

12. Silver mirror test is given by:

A) Ketones only
B) Aldehydes only
C) Alcohols only
D) Ethers only

Answer: B) Aldehydes only

13. Fehling’s solution gives a brick-red precipitate due to:

A) Ag
B) CuO
C) Cu₂O
D) CuSO₄

Answer: C) Cu₂O

14. Aldol condensation requires:

A) Halogen atom
B) α-Hydrogen
C) Nitro group
D) Carboxyl group

Answer: B) α-Hydrogen

15. Cannizzaro reaction is shown by aldehydes having:

A) α-Hydrogen
B) No α-Hydrogen
C) Ketone group
D) Alcohol group

Answer: B) No α-Hydrogen

16. Clemmensen reduction uses:

A) Zn(Hg)/HCl
B) NH₂NH₂/KOH
C) NaBH₄
D) LiAlH₄

Answer: A) Zn(Hg)/HCl

17. Wolff–Kishner reduction converts carbonyl compounds into:

A) Alcohols
B) Acids
C) Hydrocarbons
D) Esters

Answer: C) Hydrocarbons

18. The functional group of carboxylic acids is:

A) –CHO
B) –COOH
C) –CO–
D) –OH

Answer: B) –COOH

19. Carboxylic acids have high boiling points because of:

A) Ionic bonding
B) Hydrogen bonding
C) Metallic bonding
D) Resonance only

Answer: B) Hydrogen bonding

20. The IUPAC suffix used for carboxylic acids is:

A) –ol
B) –al
C) –one
D) –oic acid

Answer: D) –oic acid

21. Carboxylic acids react with sodium bicarbonate to release:

A) H₂
B) O₂
C) CO₂
D) N₂

Answer: C) CO₂

22. Esterification reaction occurs between:

A) Acid and alcohol
B) Acid and alkene
C) Alcohol and ketone
D) Aldehyde and acid

Answer: A) Acid and alcohol

23. The preferred reagent for converting acid into acid chloride is:

A) SOCl₂
B) NaOH
C) KMnO₄
D) HCN

Answer: A) SOCl₂

24. Reduction of carboxylic acid gives:

A) Aldehyde
B) Primary alcohol
C) Ketone
D) Alkane

Answer: B) Primary alcohol

25. HVZ reaction involves:

A) Reduction of acid
B) α-halogenation of acid
C) Ester formation
D) Decarboxylation

Answer: B) α-halogenation of acid

SECTION B: Fill in the Blanks

1. Aldehydes contain the functional group ______.

Answer: –CHO

2. Carbonyl carbon is ______ hybridised.

Answer: sp²

3. Formaldehyde is the simplest ______.

Answer: aldehyde

4. Ketones contain a carbonyl group attached to ______ carbon atoms.

Answer: two

5. Aldehydes are oxidised to ______ acids.

Answer: carboxylic

6. Tollens’ reagent contains ______ ions.

Answer: silver (Ag⁺)

7. Fehling’s test produces ______ precipitate.

Answer: brick-red

8. Aldol condensation requires the presence of ______ hydrogen.

Answer: alpha (α)

9. Cannizzaro reaction occurs in aldehydes without ______ hydrogen.

Answer: α

10. Carboxylic acids contain the group ______.

Answer: –COOH

11. Esterification requires concentrated ______ acid as catalyst.

Answer: sulphuric

12. Grignard reagent reacts with CO₂ to form ______ acids.

Answer: carboxylic

13. Decarboxylation removes ______ from carboxylic acids.

Answer: CO₂

14. SOCl₂ converts carboxylic acids into ______ chlorides.

Answer: acid

15. HVZ reaction gives ______ halo carboxylic acids.

Answer: α

SECTION C: Assertion–Reason Questions

Choose:

A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true but R is false
D) A is false but R is true

1.

Assertion: Aldehydes are more reactive than ketones.

Reason: Ketones have greater steric hindrance.

Answer: A

2.

Assertion: Carboxylic acids have higher boiling points than aldehydes.

Reason: Carboxylic acids form hydrogen-bonded dimers.

Answer: A

3.

Assertion: Ketones do not give Tollens’ test.

Reason: Ketones are easily oxidised.

Answer: C

4.

Assertion: Electron withdrawing groups increase acidity of carboxylic acids.

Reason: They stabilise carboxylate ions.

Answer: A

5.

Assertion: Methanal undergoes Cannizzaro reaction.

Reason: Methanal has no α-hydrogen.

Answer: A

SECTION D: Match the Following

Column AColumn B
Rosenmund reductionAcid chloride → Aldehyde
Clemmensen reductionC=O → CH₂
Tollens testSilver mirror
HVZ reactionα-halogenation
EsterificationAcid + Alcohol

SECTION E: Very Short Answer Questions

1. Why are aldehydes more reactive than ketones?

Answer: Due to lower steric hindrance and only one electron-donating alkyl group.

2. Name the product of oxidation of aldehyde.

Answer: Carboxylic acid.

3. Which compound gives silver mirror test?

Answer: Aldehydes.

4. What is cyanohydrin?

Answer: Product formed by addition of HCN to aldehydes or ketones.

5. Name the reaction converting acid chloride into aldehyde.

Answer: Rosenmund reduction.

6. Which reaction converts carbonyl compounds into hydrocarbons?

Answer: Clemmensen and Wolff–Kishner reduction.

7. What is esterification?

Answer: Reaction between carboxylic acid and alcohol forming ester.

8. Which test confirms carboxylic acid group?

Answer: Sodium bicarbonate test.

9. Why is SOCl₂ preferred for acid chloride formation?

Answer: Products SO₂ and HCl escape as gases, making purification easy.

10. What is decarboxylation?

Answer: Removal of CO₂ from carboxylic acid salts.

Total High-Value Questions:

  • MCQs: 25
  • Fill in blanks: 15
  • Assertion Reason: 5
  • Match: 5 pairs
  • Very Short Answers: 10

Total Revision Questions: 60