Lesson 3.3.6.1

3.3.6.1 Identification of functional groups by test-tube reactions Quiz: AQA Chemistry, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.6.1, Identification of functional groups by test-tube reactions: 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 reagent forms a silver mirror when warmed with an aldehyde?

    • Bromine water
    • Fehling's solution
    • Tollens' reagent
    • Acidified potassium dichromate(VI)

  2. Which reagent gives a brick-red precipitate with an aldehyde on warming?

    • Fehling's solution
    • Sodium carbonate solution
    • Bromine water
    • Tollens' reagent

  3. Which functional group decolourises bromine water at room temperature?

    • Alkane (C-C single bonds only)
    • Alkene (C=C double bond)
    • Carboxylic acid (COOH group)
    • Ketone (C=O in a chain)

  4. Which gas is released when a carboxylic acid reacts with sodium carbonate solution?

    • Hydrogen
    • Carbon dioxide
    • Oxygen
    • Carbon monoxide

  5. Which compound does NOT give a brick-red precipitate with Fehling's solution on warming?

    • Ethanal
    • Butanal
    • Propanal
    • Propanone

  6. A compound gives orange-to-green with acidified dichromate(VI) and a silver mirror with Tollens' reagent. Which group is most likely present?

    • Alkene
    • Tertiary alcohol
    • Ketone
    • Aldehyde

  7. Which colour change is seen when a primary alcohol is warmed with acidified potassium dichromate(VI)?

    • Orange to green
    • Green to orange
    • Purple to colourless
    • Blue to brick-red

  8. Which compound gives no colour change when warmed with acidified potassium dichromate(VI)?

    • Propanal, which is oxidised to propanoic acid by warm acidified dichromate(VI)
    • Butan-2-ol, which is oxidised to a ketone by warm acidified dichromate(VI)
    • Propan-1-ol, which is oxidised to an aldehyde or acid by warm acidified dichromate(VI)
    • 2-methylpropan-2-ol

  9. Acidified potassium manganate(VII) is added to an alkene. What is observed?

    • Colourless solution turns purple
    • No visible change occurs
    • Orange solution turns green
    • Purple solution turns colourless

  10. Ethanoic acid and ethanol are both colourless liquids. Which simple test distinguishes them?

    • Tollens' reagent, which forms a silver mirror with both
    • Fehling's solution, which gives a red precipitate with both
    • Bromine water, which is decolourised by both liquids
    • Sodium carbonate solution, which fizzes only with ethanoic acid

  11. Propanone is reduced by NaBH4 in aqueous solution. What is the organic product?

    • Propan-1-ol
    • Propanal
    • Propan-2-ol
    • Propanoic acid

  12. Which product forms when butanal is reduced by [H]?

    • Butan-2-ol
    • Butanoic acid
    • Butan-1-ol
    • Butanone

  13. In the reduction of a carbonyl compound by NaBH4, which species acts as the nucleophile?

    • Bromide ion, Br-
    • Hydride ion, H-
    • Cyanide ion, CN-
    • Hydroxide ion, OH-

  14. An unknown gives a silver mirror with Tollens' reagent. Which explanation is best?

    • It contains an aldehyde group, which is oxidised to a carboxylate ion
    • It contains a C=C bond that adds silver ions across the double bond
    • It contains a carboxylic acid, which precipitates silver chloride
    • It contains a ketone, which is reduced to a secondary alcohol

  15. A compound decolourises bromine water and effervesces with sodium carbonate. Which functional groups are present?

    • Alkene and carboxylic acid
    • Ketone and carboxylic acid
    • Alkene and aldehyde
    • Alcohol and ketone

  16. Which reagent distinguishes an aldehyde from a primary alcohol, since both give orange-to-green with acidified dichromate(VI)?

    • Sodium carbonate solution
    • Sodium borohydride solution
    • Bromine water
    • Tollens' reagent

  17. A compound gives orange-to-green with acidified dichromate(VI) but no silver mirror with Tollens' reagent. Which is most likely?

    • 2-methylpropan-2-ol
    • Propan-2-ol
    • Propanone
    • Propanal

  18. A compound decolourises bromine water and gives a silver mirror with Tollens' reagent. Which structure fits?

    • CH3CH=CHCH3 (but-2-ene)
    • CH3CH2COCH3 (butanone)
    • CH2=CHCH2COOH (but-3-enoic acid)
    • CH2=CHCH2CHO (but-3-enal)

  19. Propan-1-ol is heated under reflux with excess acidified potassium dichromate(VI). What is the main organic product?

    • Propanal, the aldehyde formed after only one oxidation step of the primary alcohol
    • Propanone, a ketone that cannot be formed by oxidising a primary alcohol at all
    • Propan-2-ol, the secondary alcohol isomer of the starting primary alcohol
    • Propanoic acid

  20. Why do aldehydes and ketones behave differently in Tollens' test?

    • Ketones contain more oxygen atoms per molecule than aldehydes, so they resist mild oxidation
    • Ketones react with silver ions only when the solution is strongly acidic and has been warmed
    • An aldehyde carbonyl carbon carries a hydrogen that can be oxidised, while a ketone carbonyl carbon is bonded to two alkyl groups
    • Aldehydes have a triple bond between carbon and oxygen that reacts with silver ions directly

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