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 22 of 34
- A. Carbanion
- B. Carbocation
- C. Carbene
- D. Alkoxide ion
Explanation: The BH4- ion from NaBH4 attacks the carbonyl carbon of the aldehyde, forming an alkoxide intermediate. Therefore, option d is correct.
Correct answer: Alkoxide ion- A. Acetone
- B. Acetaldehyde
- C. Formaldehyde
- D. Carboxylic acid
Explanation: The dry distillation of calcium acetate is a common industrial process for producing acetone.
Correct answer: Acetone- A. Aldol product
- B. Alcohol and carboxylate salt
- C. Alcohol and carboxylic acid
- D. Unsaturated reaction
Explanation: The Cannizzaro reaction is a redox reaction that produces a carboxylic salt and an alcohol.
Correct answer: Alcohol and carboxylate salt- A. Aldehydes
- B. Ketones
- C. Alkanals
- D. Both A and C
Explanation: A formyl functional group consists of a carbonyl bonded to hydrogen. When attached to an R group, a formyl group is called an aldehyde…
Correct answer: Both A and C- A. Acetylides
- B. Paraldehyde
- C. Bakelite
- D. Meta acetaldehyde
Explanation: Acetaldehyde, under certain conditions like concentrated sulfuric acid, can polymerize to form paraldehyde.
Correct answer: Paraldehyde- A. Reduction of alcohol
- B. Oxidation of alcohol
- C. Dehydration of alcohol
- D. Hydrolysis of alcohol
Explanation: Option B (Oxidation of alcohol) is correct because the oxidation of primary alcohols leads to the formation of aldehydes, and the…
Correct answer: Oxidation of alcohol- A. Tollen's test
- B. Reaction with hydrazine
- C. Reaction with 2,4-dinitrophenylhydrazine
- D. Reaction with ammonia
Explanation: Tollen's test involves the use of a silver mirror test to differentiate between aldehydes and ketones.
Correct answer: Tollen's test- A. C2nHnO
- B. CnH2nO
- C. C2nHnOH
- D. CnHnO2n
Explanation: Option B is correct because this formula represents the general molecular formula for both aldehydes and ketones.
Correct answer: CnH2nO- A. Aldehyde
- B. Alkene
- C. Aldehyde & ketone equally
- D. Neither aldehyde nor alkenes
Explanation: Aldehydes undergo nucleophilic addition reactions more easily compared to alkenes and ketones.
Correct answer: Aldehyde- A. 80
- B. 8
- C. 37
- D. 52
Explanation: Formalin is a solution of formaldehyde (CH2O) gas dissolved in water. It also contains a small amount of methanol (CH3OH) as a stabilizing…
Correct answer: 8- A. More stable anion with negative charge on oxygen and less stable carbocation
- B. Electronegativity difference and pi bond
- C. Electronegative character of carbonyl carbon
- D. None of these
Explanation: Option B is correct because carbonyl compounds undergo nucleophilic addition due to the presence of the polarized carbon-oxygen double…
Correct answer: Electronegativity difference and pi bond- A. Na2CO3
- B. NaBH4
- C. KMnO4
- D. NaBH2
Explanation: A suitable reducing agent for aldehydes is sodium borohydride (NaBH4) or lithium aluminum hydride (LiAlH4).
Correct answer: NaBH4- A. Ethanol
- B. Pentan-3-one
- C. Ethanal
- D. Pentan-2-one
Explanation: Ethanol is an alcohol that contains the -OH (hydroxyl) functional group.
Correct answer: Ethanol- A. Tartaric acid
- B. Malonic acid
- C. Formic acid
- D. Lactic acid
Explanation: The correct answer is C)Formic acid. Acetaldehyde cyanohydrin hydrolyzes to form formic acid.
Correct answer: Formic acid- A. Methyl alcohol
- B. Acetaldehyde
- C. Ethyl alcohol
- D. Acetone
Explanation: The correct answer is d) Acetone. Acetone is relatively resistant to oxidation under normal conditions due to its ketone functional group…
Correct answer: Acetone- A. Fehling's reagent
- B. Tollen's reagent
- C. Hydrazine
- D. Sodium nitroprusside
Explanation: The correct answer is c) Hydrazine. Hydrazine can react with both aldehydes and ketones to form hydrazones.
Correct answer: Hydrazine- A. Cupric oxalate
- B. Cuprous tartrate
- C. Cupric amine
- D. Cupric tartrate
Explanation: The correct answer is d) Cupric tartrate. Fehling solution is a complex of cupric tartrate.
Correct answer: Cupric tartrate438. Formalin is used as:
- A. Fungicide
- B. Sterilizing of surgical instruments
- C. Germicide
- D. All of these
Explanation: Formalin is used as a fungicide, for sterilizing surgical instruments, and as a germicide.
Correct answer: All of these- A. HCN
- B. Ammonical AgNO3
- C. Cu(OH)2 / NaOH
- D. Cu(OH)2 only
Explanation: HCN reacts with aldehydes and ketones to form cyanohydrins. A cyanohydrin is formed by the nucleophilic addition of HCN across the…
Correct answer: HCN- A. Oxime formation
- B. Hydrazone formation with hydrazine
- C. Reduction with Fehling solution
- D. Reaction with HCN
Explanation: The correct answer is c) Reduction with Fehling solution. Propanone does not undergo reduction with Fehling solution because it is a…
Correct answer: Reduction with Fehling solution