Questions on Aldehydes and Ketones (Organic Chemistry)
20 multiple-choice questions with five alternatives (A–E) on Aldehydes and Ketones (Organic Chemistry). At the end, you'll find the correct answers with extended explanations.
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Multiple Choice Questions: Aldehydes and Ketones
1. What is the functional group of aldehydes?
A) –OH
B) –COOH
C) –CHO
D) –CO–
E) –NH₂
2. What is the functional group of ketones?
A) –COOH
B) –CH₃
C) –CHO
D) –CO–
E) –OH
3. What is the IUPAC name of CH₃CHO?
A) Methanal
B) Ethanal
C) Propanal
D) Acetone
E) Methanoic acid
4. Which of the following is a ketone?
A) CH₃CH₂CH₂OH
B) CH₃COCH₃
C) CH₃CHO
D) CH₃COOH
E) CH₃CH₂NH₂
5. Which of the following is a property of aldehydes?
A) Cannot be oxidized
B) Cannot be reduced
C) Easily oxidized to carboxylic acids
D) Contain nitrogen atoms
E) Are bases
6. What is the common name of propanone?
A) Formaldehyde
B) Acetaldehyde
C) Acetone
D) Butanone
E) Ethanal
7. Which of the following contains the carbonyl group (>C=O)?
A) Alcohols
B) Aldehydes and ketones
C) Alkanes
D) Alkynes
E) Amines
8. Which of these is the correct classification of acetaldehyde?
A) Alcohol
B) Ketone
C) Ester
D) Aldehyde
E) Acid
9. Which of these tests can distinguish between an aldehyde and a ketone?
A) Bromine water
B) Tollens' test
C) Baeyer's test
D) Flame test
E) Benedict's test
10. Which reagent gives a silver mirror with aldehydes?
A) HCl
B) Br₂
C) Tollens' reagent
D) Fehling's solution
E) I₂
11. What is the product when a ketone is reduced?
A) Carboxylic acid
B) Alcohol
C) Ester
D) Amine
E) Aldehyde
12. Which of these is the IUPAC name for acetone?
A) Propanone
B) Butanone
C) Propanal
D) Acetaldehyde
E) Ethanol
13. What type of compound is CH₃CH₂COCH₃?
A) Aldehyde
B) Ketone
C) Carboxylic acid
D) Alcohol
E) Ester
14. What is the suffix used for naming aldehydes in IUPAC nomenclature?
A) –ol
B) –al
C) –one
D) –ic acid
E) –ane
15. What is the suffix used for naming ketones in IUPAC nomenclature?
A) –one
B) –al
C) –ic
D) –yl
E) –ate
16. What is the result of oxidation of an aldehyde?
A) Ketone
B) Ester
C) Alcohol
D) Carboxylic acid
E) Alkene
17. Which of the following carbonyl compounds is more reactive toward nucleophiles?
A) Ketones
B) Aldehydes
C) Carboxylic acids
D) Esters
E) Amides
18. What is the boiling point trend between aldehydes and ketones of similar size?
A) Aldehydes have much higher boiling points
B) Ketones have slightly higher boiling points
C) Aldehydes and ketones have equal boiling points
D) Aldehydes have higher boiling points than ketones
E) None of the above
19. Which intermolecular force is most important in pure liquid aldehydes and ketones?
A) Ionic bonding
B) Hydrogen bonding
C) Covalent bonding
D) Dipole–dipole interactions
E) Metallic bonding
20. Which of the following statements is TRUE about ketones?
A) They can be oxidized to carboxylic acids easily
B) They do not contain a carbonyl group
C) They have the general formula R–CO–R'
D) They give a positive Tollens' test
E) They are always solids at room temperature
- Questions about Aromatic Hydrocarbons (Organic Chemistry)
- Questions about Alcohols (Organic Chemistry)
- Questions about Ethers (Organic Chemistry)
✅ Answer Key with Extended Explanations
1. C – Aldehydes contain the –CHO group, a carbon double-bonded to oxygen and single-bonded to hydrogen.
2. D – Ketones contain the –CO– group (carbonyl) between two carbon atoms.
3. B – CH₃CHO is ethanal, a two-carbon aldehyde.
4. B – CH₃COCH₃ is propanone, a ketone with a central carbonyl group.
5. C – Aldehydes are easily oxidized to carboxylic acids (–COOH).
6. C – Acetone is the common name for propanone, a simple ketone.
7. B – Aldehydes and ketones both contain the carbonyl group (>C=O).
8. D – Acetaldehyde is the common name for ethanal, an aldehyde.
9. B – Tollens’ test distinguishes aldehydes (silver mirror test).
10. C – Tollens' reagent reacts with aldehydes to produce a silver mirror.
11. B – Reduction of a ketone produces a secondary alcohol.
12. A – Acetone = propanone (3-carbon ketone).
13. B – CH₃CH₂COCH₃ is a ketone, specifically butan-2-one.
14. B – Aldehydes are named with the suffix –al in IUPAC.
15. A – Ketones are named with the suffix –one in IUPAC.
16. D – Aldehydes are oxidized to carboxylic acids.
17. B – Aldehydes are more reactive than ketones due to less steric hindrance.
18. B – Ketones tend to have slightly higher boiling points than aldehydes.
19. D – Dipole–dipole interactions are significant due to the polar carbonyl group.
20. C – Ketones have the general formula R–CO–R'.
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