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 6 of 34
- A. 2-Chloro-4-methylpentanal
- B. 2-Methyl-4-chloropentanal
- C. 2-Chloro-3-methylbutanol
- D. 3-Methyl-2-chloropentanal
Explanation: The correct answer is A . According to IUPAC system , the numbering of Carbon should start from C=O side and the branches should be…
Correct answer: 2-Chloro-4-methylpentanal- A. Electrophilic addition reaction
- B. Electrophilic substitution reaction
- C. Nucleophilic addition reaction
- D. Nucleophilic substitution reaction
Explanation: C is the correct option , as we can clearly see nucleophile being added into the reactant thus, making it nucleophilic addition reaction.
Correct answer: Nucleophilic addition reaction- A. Acetic acid
- B. Acetic acid & Ethane
- C. Methane & Propanoic acid
- D. Propanoic acid & Methanoic acid
Explanation: 2-Butanone is a methyl ketone (CH₃-CO-CH₂-CH₃).On oxidation with K2Cr2O7 /H2SO4, the ketone undergoes cleavage at the carbonyl, forming…
Correct answer: Propanoic acid & Methanoic acid- A. Aldehydes
- B. Aldehydes and ketones
- C. Carboxylic acids
- D. Ethers
Explanation: 2,4-DNP reacts with the carbonyl group of aldehydes and ketones to form yellow/orange hydrazones.
Correct answer: Aldehydes and ketones- A. Ethanal
- B. Glucose
- C. Acetone
- D. Methanal
Explanation: Fehling's reagent oxidizes aldehydes but not ketones. Acetone is a ketone and remains unreactive.
Correct answer: Acetone- A. Ethanol
- B. Ethanoic acid
- C. 2-hydroxypropanenitrile
- D. 2-hydroxybutanenitrile
Explanation: HCN adds across the carbonyl group forming a cyanohydrin.CH₃-CHO → CH₃-CH(OH)-CN.
Correct answer: 2-hydroxypropanenitrile- A. Wolff-Kishner reduction
- B. Reduction with NaBH₄
- C. Oxidation
- D. Clemmensen reduction
Explanation: NaBH₄ reduces aldehydes to primary alcohols and ketones to secondary alcohols.
Correct answer: Reduction with NaBH₄108. Which of the following reagent is used to separate and purify carbonyl and non carbonyl compounds?
- A. HCN
- B. BrMgCH3
- C. NaHSO3
- D. H2O
Explanation: Sodium bisulfite reacts selectively with carbonyl compounds to form stable, crystalline bisulfite adducts.
Correct answer: NaHSO3- A. K2Cr2O7 (acidified)
- B. KMnO4 (alkaline)
- C. Ammonical AgNO3
- D. All of above
Explanation: Aldehydes are easily oxidised to corresponding carboxylic acids even by mild oxidizing agents such as Tollen's Reagent (Ammoniacal silver…
Correct answer: Ammonical AgNO3- A. Hybridization of C-atom
- B. Planar structures
- C. Bond length
- D. Undergo addition reaction
Explanation: Unlike a C=C double bond, the C=O bond has a dipole. The electrons in the sigma and pi bonds are more attracted to the O than the C.
Correct answer: Bond length- A. Electrophilic carbon
- B. Less stearic hindrance
- C. Unsaturation ofC = c
- D. All of above
Explanation: The carbonyl group has a s-bond and a p-bond. Thus it can undergo addition reactions.
Correct answer: All of above- A. 2 molecules of Ca(CH3COO)2
- B. 1 mole of Ca(CH3COO)2 and 1 molecule of Ca(HCOO)2
- C. 2 molecules of Ca(HCOO)2
- D. None of these
Explanation: Acetone is prepared by drydistillation of calcium acetate
Correct answer: 1 mole of Ca(CH3COO)2 and 1 molecule of Ca(HCOO)2- A. Acetone
- B. Benzophenone
- C. Diethyl ketone
- D. Acetophenone
Explanation: Acetophenone is mixed ketone because it is made of ketone and phenol functional group
Correct answer: Acetophenone- A. CH3OH
- B. C2H5OH
- C. CH3CHO
- D. CH3COCH3
Explanation: Ketones cannot react under normal conditions because ketones do not have a hydrogen atom attached to their carbonyl.
Correct answer: CH3COCH3- A. HCHO
- B. CH3CHO
- C. C6H5CHO
- D. All of above
Explanation: Indeed, formaldehyde is highly reactive due to its electrophilic nature, especially in the presence of compounds that can donate…
Correct answer: HCHO- A. P alcohol
- B. S alcohol
- C. T alcohol
- D. None of these
Explanation: Primary alcohols can be oxidized to form aldehydes and carboxylic acids; secondary alcohols can be oxidized to give ketones.
Correct answer: S alcohol- A. Formaldehyde
- B. Acetaldehyde
- C. Benzaldehyde
- D. None of above
Explanation: "As acetaldehyde has alpha hydrogen, it gives aldol condensation, not canizerous.
Correct answer: Acetaldehyde- A. Fehling solution test
- B. Tollen's reagent test
- C. Schiff's reagent test
- D. Sodium nitroprusside test
Explanation: Sodium Nitroprusside Test:Ketones produce a wine red or orange red colour on adding alkalinesodium nitroprusside solution dropwise.
Correct answer: Sodium nitroprusside test- A. Aldehyde
- B. Alkene
- C. Aldehyde and ketone
- D. All of these
Explanation: As aldehyde isattached to hydrogen a withdrawing group so nucleophile can easily attack So which is why aldehyde undergoes nucleophilic…
Correct answer: Aldehyde- A. Acetaldehyde
- B. Acetone
- C. Formaldehyde
- D. Ethyl alcohol
Explanation: (a) Uses of Fomaldehyde(i) It is used in the manufacture of resins like urea-formaldehyde and plasticssuch as bakelite.(ii) It is used in…
Correct answer: Formaldehyde