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 32 of 34
- A. Formaldehyde
- B. Aceteldehyde
- C. Acetone
- D. Ethanol
Explanation: Formaldehyde does not have a methyl group adjacent to a carbonyl group, which is necessary for the iodoform reaction to occur.
Correct answer: Aceteldehyde- A. Option A: Gem diol with no electron-withdrawing groups
- B. Option B: Gem diol with a weak electron-withdrawing group
- C. Option C: Gem diol with a strong electron-withdrawing group
- D. Option D: Gem diol with a bulky substituent
Explanation: The stability of a geminal diol is significantly influenced by the presence of electron-withdrawing groups attached to the carbon that…
Correct answer: Option C: Gem diol with a strong electron-withdrawing group- A. 2, 4 - DNPH
- B. Iodine in NaOH
- C. Sodium nitroprusside
- D. hydrogen cyanide
Explanation: Iodoform test (I₂ / NaOH) is the correct reagent for distinguishing methyl ketones
Correct answer: Iodine in NaOH- A. Carbon
- B. Magnesium
- C. Halogen
- D. None of the above
Explanation: The explanation for this question will be added soon.
Correct answer: Magnesium- A. Beta hydroxy carboxylic acids
- B. Alpha hydroxy carboxylic acids
- C. Carboxylic acids
- D. Unsaturated acids
Explanation: The hydrolysis of cyanohydrin gives alpha hydroxy, carboxylic acids. In the above reaction, the cyano group is hydrolyzed to a carboxylic…
Correct answer: Alpha hydroxy carboxylic acids- A. Acid.
- B. Base.
- C. Water.
- D. Both acid and base.
Explanation: Nucleophilic addition reactions of carbonyl compounds involve the addition of a nucleophile (an electron-rich species) to the carbon atom…
Correct answer: Both acid and base.- A. Elimination+ addition
- B. Elimination+ Substitution
- C. Addition + substitution
- D. None of these
Explanation: Condensation involves elimination and addition. It is a reaction in which a water molecule is produced as a by-product.
Correct answer: Elimination+ addition628. In the addition of sodium bisulfite to carbonyl system, which of the following is a nucleophile?
- A. Sulphide ion
- B. Sulfite ion
- C. Hydride ion
- D. Sodium ion
Explanation: The addition of sodium bisulfite to a carbonyl group takes place as follows:Sodium bisulfite ionizes to form sulfite ions.The sulfite ion…
Correct answer: Sulfite ion- A. Hydroxyl ion
- B. Carbocation
- C. Carbanion
- D. Water
Explanation: The reaction mechanism below shows that the carbanion is the nucleophile of the reaction:
Correct answer: Carbanion- A. Carbanion
- B. Carbocation
- C. Carbene
- D. Alkoxide ion
Explanation: During the reduction of aldehydes with NaBH4, the "alkoxide ion" is seen as the intermediate formed hence the answer is D.
Correct answer: Alkoxide ion- A. CH3CH2CH3CH3CHO
- B. CH3CH2CH2COCH3
- C. CH3CH2CH(CH3)CHO
- D. CH3CH2COCH2CH3
Explanation: b) CH3CH2CH2COCH3:This compound is 2-pentanone, which is a ketone with the molecular formula C5H10O.
Correct answer: CH3CH2CH2COCH3- A. Acetaldehyde
- B. Acetone
- C. Aldehydes
- D. Alkene
Explanation: NaBH4 cannot reduce alkenes into alkanes because in a C=C there is no nucleophilic nature, the H- ion needs a positive carbon to attack…
Correct answer: Alkene633. 50% NaOH is used in:
- A. Aldol condensation reaction
- B. Cannizaro reaction
- C. Clemenson condensation reaction
- D. Wolfkishner reaction
Explanation: According to PTB page 237, 50% concentrated NaOH solution is generally used in Cannizaro reaction as it is used for aldehydes which do not…
Correct answer: Cannizaro reaction- A. Formaldehyde
- B. Acetaldehyde
- C. Acetone
- D. Butanone
Explanation: The Cannizzaro reaction is basically a chemical reaction which involves the base-induced disproportionation of an aldehyde lacking a…
Correct answer: Formaldehyde- A. Butanal
- B. Methanal
- C. Ethanal
- D. All of these
Explanation: Option A: Butanal, also known as butyraldehyde, is an aldehyde with the chemical formula C4H8O.
Correct answer: All of these- A. Acetaldehyde
- B. 3-hexanone
- C. Butanone
- D. Acetone
Explanation: 3-hexanone does not give the iodoform test. The iodoform test is a chemical test used to detect the presence of methyl ketones.
Correct answer: 3-hexanone- A. Nucleophilic
- B. Electrophilic
- C. Neutral
- D. All of these options are correct
Explanation: The carbon present in aldehyde is electrophilic. An electrophile is a molecule or ion that has a partial positive charge and is attracted…
Correct answer: Electrophilic- A. Ketones
- B. Hydrocarbons
- C. Alcohols
- D. Ethers
Explanation: Grignard reagent,R-Mg-X, reacts with carbonyl group in aldehydes to give secondary alcohols with the exception of methanal which gives…
Correct answer: Alcohols- A. Propanone
- B. 3-Propanone
- C. 2-Butanone.
- D. 2-Propanone.
Explanation: "Propane-2-one," tells us that acetone is a compound with a three-carbon chain (propane) and a ketone functional group (-C=O) on the…
Correct answer: 2-Propanone.- A. Alkenes
- B. Alkanes
- C. Alkynes
- D. Alcohols
Explanation: Option B is correct since the reduction of aldehydes and ketones to alkanes is done in Wolff Krishner's reaction.
Correct answer: Alkanes