Lesson 3.3.8

3.3.8 Aldehydes and ketones Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.8, Aldehydes and ketones: 20 multiple choice questions for the AQA Chemistry (7405), Unit 3: Organic chemistry, written with Revision Ninja.

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The 20 questions

  1. Which type of reaction is the reduction of an aldehyde by NaBH4?

    • Free-radical substitution
    • Elimination
    • Nucleophilic addition
    • Electrophilic substitution

  2. What is the product when a ketone is reduced by NaBH4 in aqueous solution?

    • An ester
    • A carboxylic acid
    • A secondary alcohol
    • A primary alcohol

  3. What specific hazard is associated with KCN in the hydroxynitrile reaction?

    • KCN dissolves all glass in the laboratory, so it must be kept in plastic containers
    • KCN is highly toxic and releases toxic HCN gas when acidified
    • KCN is radioactive and emits gamma rays, so it must be handled behind shielding
    • KCN is explosive when heated in air, so it must be stored away from any heat

  4. Why does an unsymmetrical ketone or aldehyde react with KCN and dilute acid to give a mixture of enantiomers?

    • The cyanide ion always reacts with the oxygen atom of the carbonyl group first
    • Dilute acid converts the product into a racemic salt that cannot be separated later
    • The planar carbonyl carbon can be attacked from either face, giving equal amounts of each enantiomer
    • The reaction produces a polymer chain instead of a single hydroxynitrile product

  5. Which pair of reagents distinguishes aldehydes from ketones?

    • Tollens' reagent and Fehling's solution
    • NaBH4 and KCN
    • Bromine water and Tollens' reagent
    • Sodium carbonate and Fehling's solution

  6. Which equation correctly shows the reduction of ethanal using [H] as the reductant?

    • CH3CHO + 2[H] -> CH3COOH
    • CH3CHO + [H] -> CH3CH2OH
    • CH3CHO + 2[H] -> CH3CH2OH
    • CH3CHO + [H] -> CH3COOH

  7. What is the product when propanal reacts with HCN and then forms the hydroxynitrile?

    • 2-hydroxypropanenitrile
    • 2-hydroxybutanenitrile
    • Propan-2-ol
    • Butanoic acid

  8. Propanone reacts with KCN followed by dilute acid. Which statement about the product is correct?

    • It contains a chiral carbon bonded to two CH3 groups
    • It is a racemic mixture of two enantiomers
    • It has no chiral centre, so no enantiomers are formed
    • It is an ester formed by acid-catalysed reaction

  9. In the KCN then dilute acid reaction, what is the role of the dilute acid?

    • It protonates the alkoxide ion formed after cyanide attacks
    • It removes the cyanide ion from the product so that only the alcohol remains
    • It oxidises the product to a carboxylic acid so that the reaction is complete
    • It reduces the carbonyl group to an alcohol, replacing the need for cyanide

  10. In reduction with NaBH4 in aqueous solution, how is the alkoxide intermediate converted to the alcohol?

    • Addition of a halogen
    • Oxidation by sodium ions
    • Elimination of hydride
    • Protonation by water

  11. Butanone is reduced by NaBH4 in aqueous solution. What is the product and is it chiral?

    • Butan-1-ol, which is achiral
    • Butan-2-ol, which is chiral
    • Butan-2-ol, which is achiral
    • Butanoic acid, which is chiral

  12. What is the equation for the reduction of propanone by [H]?

    • CH3COCH3 + [H] -> CH3CH2CH2OH
    • CH3COCH3 + 2[H] -> CH3CH2COOH
    • CH3COCH3 + 2[H] -> CH3CH(OH)CH3
    • CH3COCH3 + [H] -> CH3COOH

  13. Why does Fehling's solution oxidise aldehydes but not ketones?

    • Aldehydes contain no oxygen atoms, so they cannot be oxidised by any reagent
    • Aldehydes have a C-H on the carbonyl carbon that can be oxidised to a carboxylic acid
    • Ketones are always reduced by Fehling's solution, so no oxidation product forms
    • Ketones contain a triple bond that blocks oxidation by mild reagents in solution

  14. Ethanal and propanone are both reduced by NaBH4 in aqueous solution. Which pair of products forms?

    • Ethanoic acid and propan-2-ol
    • Ethanol and propan-2-ol
    • Ethanal and propanone
    • Propan-1-ol and ethanol

  15. Which ketone does NOT form a pair of enantiomers after reaction with KCN and dilute acid?

    • Propanone
    • Ethanal
    • Pentan-2-one
    • Butanal

  16. What is the functional group formed when an aldehyde is oxidised?

    • Alkene (C=C)
    • Primary amine (-NH2)
    • Ester (-COO-)
    • Carboxylic acid (-COOH)

  17. Which statement about the nucleophilic addition of KCN and dilute acid to a carbonyl compound is correct?

    • The cyanide ion attacks the carbon of the C=O group
    • The reaction forms a double bond to nitrogen
    • The cyanide ion attacks the hydrogen of the C=O group
    • The carbonyl oxygen is removed as water

  18. Which compound with formula C4H8O gives a silver mirror with Tollens' reagent?

    • Butanone
    • But-3-en-1-ol
    • Cyclobutanol
    • Butanal

  19. Which statement about NaBH4 in aqueous solution is correct?

    • It oxidises aldehydes to carboxylic acids, while leaving ketones fully unchanged
    • It reduces ketones to primary alcohols only, leaving aldehydes unchanged
    • It reduces aldehydes to alkanes, removing the oxygen from the carbonyl group
    • It reduces aldehydes to primary alcohols and ketones to secondary alcohols

  20. What is the relative molecular mass of the hydroxynitrile formed from ethanal and HCN, CH3CH(OH)CN?

    • 57
    • 71
    • 69
    • 85

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