Free Aldehydes and Ketones MCQs with Answers
679 Aldehydes and Ketones MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Aldehydes and ketones contain the polar carbonyl group, but aldehydes are generally more readily oxidised and more reactive than ketones. Coverage includes preparation by oxidation or reduction routes, nucleophilic addition of reagents such as hydrogen cyanide and bisulfite, and tests that distinguish aldehydes from ketones.
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679 questions · page 34 of 34
- A. CH3CH2OH
- B. CH3CH2CHO
- C. CH3CH(OH)CH2CH3
- D. CH3CH2CH2OH
Explanation: The correct answer is CH3CH(OH)CH2CH3. In this Grignard reaction, the ethyl group from the Grignard reagent (CH3CH2MgBr) adds to the…
Correct answer: CH3CH(OH)CH2CH3- A. A compound formed by the reaction of an aldehyde with hydrazine.
- B. A compound formed by the reaction of an aldehyde with water.
- C. A compound formed by the reaction of an aldehyde with an amine.
- D. A compound formed by the reaction of an aldehyde with hydrogen cyanide.
Explanation: Aldehyde hydrazones are organic compounds derived from the reaction of aldehydes with hydrazine (NH2-NH2) or its derivatives.
Correct answer: A compound formed by the reaction of an aldehyde with hydrazine.663. Aldehydes undergo:
- A. Electrophilic addition reaction
- B. Substitution reaction
- C. Nucleophilic addition reaction
- D. None of these
Explanation: So, when aldehydes undergo nucleophilic addition reactions, it means that a nucleophile (a species with a lone pair of electrons) attacks…
Correct answer: Nucleophilic addition reaction- A. Aldehyde
- B. Ketone
- C. Acid halide
- D. Carboxylic acid
Explanation: Grignard's reagent (RMgX) reacts with ketones to produce tertiary alcohols.
Correct answer: Ketone- A. To act as strong acid
- B. To act as nucleophile and add to carbonyl compounds
- C. To act as electrophile
- D. To catalyze hydrogenation reaction
Explanation: Grignard reagents are highly reactive nucleophiles that add to carbonyl compounds such as aldehydes and ketones to form addition products.
Correct answer: To act as nucleophile and add to carbonyl compounds- A. A red precipitate of CuO is formed
- B. A black precipitate of CuO is formed
- C. Silver mirror is formed
- D. No reaction occurs
Explanation: Aldehyde reacts with Fehling reagent through the following reaction: Diagram This is an oxidation reaction in which copper oxidizes alkyl…
Correct answer: A red precipitate of CuO is formed- A. CH3COOH
- B. C2H5OH
- C. OHC.OHC
- D. None of the above
Explanation: An aldehyde on oxidation with an oxidizing agent (such as one given in qs) gives its respective carboxylic acid. A is a carboxylic acid.
Correct answer: CH3COOH- A. Cu (I) oxide
- B. Ethanal
- C. Acetone
- D. Phenol
Explanation: Ethanal is an aldehyde and is capable of reducing Cu (ll) ions to Cu (l) ions. It will give a positive test with Fehling's solution.
Correct answer: Ethanal- A. Hoffman reagent
- B. Grignard reagent
- C. Tollens reagent
- D. Cannizaro reagent
Explanation: Tollen's reagent, which is a solution of silver nitrate in aqueous ammonia, is used to test for the presence of aldehydes and…
Correct answer: Tollens reagent- A. Talons test
- B. Fehling test
- C. Bacyer test
- D. Benedict test
Explanation: Bacyer's test is not used to identify aldehydes. Instead, it is used to detect the presence of unsaturation in organic compounds, such as…
Correct answer: Bacyer test- A. Benzaldehyde
- B. 2-Pentanone
- C. 3-Hexanone
- D. 3-Pentanone
Explanation: The iodoform test is a chemical reaction used to identify methyl ketones, which contain a CH3 group directly bonded to the carbonyl…
Correct answer: 2-Pentanone- A. Bacyer's test
- B. Fehling's test
- C. Silver mirror test
- D. Both (B) and (c)
Explanation: Both fehling's test and silver mirror test also known as tollens' test is used to distinguish between aldehydes and ketones.
Correct answer: Both (B) and (c)- A. Propanone
- B. Ethanol
- C. Butanone
- D. Methanol
Explanation: It does not have methyl group attached to alpha carbon so it will not give idoform test
Correct answer: Methanol- A. Ethanol
- B. Ethanoic acid
- C. Ethane
- D. Ethylene
Explanation: H2/Ni are strong reducing agents which reduces aldehydes to primary alcohols and ketones to secondary alcohols.
Correct answer: Ethanol- A. Acetone
- B. Ethyl acetate
- C. Formaldehyde
- D. Acetic acid
Explanation: Although both aldehydes and ketones contain the carbonyl functional group (-C=O), only aldehydes give a positive test (formation of an…
Correct answer: Formaldehyde- A. Grignard reduction
- B. Clemmenson reduction
- C. Wolf-kishner reduction
- D. Friedel-craft reduction
Explanation: The Clemmensen reduction is a reaction that is used to reduce aldehydes or ketones to alkanes using hydrochloric acid and zinc amalgam.
Correct answer: Clemmenson reduction- A. Acetophenon
- B. Phenylethanone
- C. Phenyl ethanal
- D. Phenylacetate
Explanation: The correct IUPAC name for the compound is 'Phenylethanone'. This compound is a ketone with a phenyl group attached to the carbonyl group…
Correct answer: Phenylethanone- A. Acidified KMnO4
- B. Acidified K2Cr2O7
- C. Ag2O
- D. Both A and B
Explanation: The correct answer is Both A and B because both acidified KMnO4 and acidified K2Cr2O7 are strong oxidizing agents capable of oxidizing…
Correct answer: Both A and B- A. Catalytic reduction
- B. Metal hydride
- C. Clemmensen method
- D. Lindlar's catalyst
Explanation: The carbon of the carbonyl group is reduced by metal hydrides. Metal hydrides, such as lithium aluminum hydride (LiAlH4) or sodium…
Correct answer: Metal hydride