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Organic compounds: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 2.4 Organic compounds, 2016–2025, with its mark scheme and examiner’s report.

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1,204 questions

  1. Q5(c)(i)

    Summer 2025 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2025 Unit 4, question 5(c)(i): Explain why the boiling temperatures of these compounds increase as shown. [1]

  2. Q5(c)(ii)

    Summer 2025 · Unit 4

    2 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2025 Unit 4, question 5(c)(ii): Predict the boiling temperature of hexylbenzene. Give your reasoning. [2]

  3. Q5(c)(iii)

    Summer 2025 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2025 Unit 4, question 5(c)(iii): Explain why the boiling temperature of 4-ethylphenol is higher than that of ethoxybenzene, even though they are both isomers of formula C8H10O. [1] HO CH2CH3 CH

  4. Q1

    Summer 2025 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2025 AS Unit 2, question 1: Draw the skeletal formula of pentane-2,4-diol. [1]

  5. Q2

    Summer 2025 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2025 AS Unit 2, question 2: Give the name of the straight chain alkane that has the same molecular formula as 2,2,4-trimethylpentane. [1]

  6. Q9(a)(iii)

    Summer 2024 · Unit 4

    3 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2024 Unit 4, question 9(a)(iii): Hydrolysis of the ester gives ethanedioic acid and butan-1-ol. Explain why ethanedioic acid is soluble in water but di-1-butyl ethanedioate is virtually insolub

  7. Q1

    Summer 2024 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2024 AS Unit 2, question 1: Give the name of the compound shown. [1] H H H H CH3 C C C C H CH3 H H H

  8. Q3

    Summer 2024 · AS Unit 2

    2 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2024 AS Unit 2, question 3: Give the molecular and empirical formulae of the compound shown. [2] OH O Molecular formula Empirical formula

  9. Q1

    Summer 2023 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2023 Unit 4, question 1: Give the structure of an unsaturated aldehyde of molecular formula C4H6O. [1]

  10. Q8(e)

    Summer 2023 · Unit 4

    2 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2023 Unit 4, question 8(e): The solubility of unsaturated carboxylic acids in water decreases as the chain length increases. Number of carbon atoms Solubility in water at 25 °C / g dm−3 in

  11. Q12(c)(i)

    Summer 2023 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2023 Unit 4, question 12(c)(i): Give the systematic name of this halogenoalkane. [1]

  12. Q1

    Summer 2023 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2023 AS Unit 2, question 1: Give the molecular formula of the compound shown. [1] O OH Molecular formula

  13. Q4

    Summer 2023 · AS Unit 2

    2 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2023 AS Unit 2, question 4: Cyclobutane is a cyclic hydrocarbon whose structure is shown. H H H C C H H C C H H H Draw the structures of two structural isomers of this compound. [2]

  14. Q13(a)(i)

    Summer 2023 · AS Unit 2

    3 marks2.4 Organic compounds
    The whole paper ↗
    Summer 2023 AS Unit 2, question 13(a)(i): Use the diagram below to show the intermolecular forces that allow ethane-1,2-diol to dissolve in water. [3] H H H C C O O H H H

  15. Q13(a)(ii)

    Summer 2023 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2023 AS Unit 2, question 13(a)(ii): Suggest a reason why the addition of ethane-1,2-diol lowers the freezing temperature of water. [1]

  16. Q7(a)(ii)

    Summer 2022 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2022 Unit 4, question 7(a)(ii): Give the structure of an isomer that is both a ketone and a secondary alcohol. [1]

  17. Q12(b)(iv)

    Summer 2022 · Unit 4

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2022 Unit 4, question 12(b)(iv): Fats and oils are esters of carboxylic acids and glycerol. Give the systematic name of glycerol (seen in part (iii) above). [1]

  18. Q6(a)(i)

    Summer 2022 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2022 AS Unit 2, question 6(a)(i): Circle the species that represents the electrophile. [1]

  19. Q6(a)(ii)

    Summer 2022 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2022 AS Unit 2, question 6(a)(ii): Name the type of bond fission that takes place in the H Br bond in the first step of the mechanism. [1]

  20. Q7(a)(i)

    Summer 2022 · AS Unit 2

    1 mark2.4 Organic compounds
    The whole paper ↗
    Summer 2022 AS Unit 2, question 7(a)(i): Give the meaning of the term ‘structural isomer’. [1]
All 36 questions on Organic compounds, as a list
  1. Summer 2025, Unit 4, Q5(c)(i) (1 mark): Explain why the boiling temperatures of these compounds increase as shown. [1]
  2. Summer 2025, Unit 4, Q5(c)(ii) (2 marks): Predict the boiling temperature of hexylbenzene. Give your reasoning. [2]
  3. Summer 2025, Unit 4, Q5(c)(iii) (1 mark): Explain why the boiling temperature of 4-ethylphenol is higher than that of ethoxybenzene, even though they are both isomers of formula C8H10O. [1] HO CH2CH3 CH
  4. Summer 2025, AS Unit 2, Q1 (1 mark): Draw the skeletal formula of pentane-2,4-diol. [1]
  5. Summer 2025, AS Unit 2, Q2 (1 mark): Give the name of the straight chain alkane that has the same molecular formula as 2,2,4-trimethylpentane. [1]
  6. Summer 2024, Unit 4, Q9(a)(iii) (3 marks): Hydrolysis of the ester gives ethanedioic acid and butan-1-ol. Explain why ethanedioic acid is soluble in water but di-1-butyl ethanedioate is virtually insolub
  7. Summer 2024, AS Unit 2, Q1 (1 mark): Give the name of the compound shown. [1] H H H H CH3 C C C C H CH3 H H H
  8. Summer 2024, AS Unit 2, Q3 (2 marks): Give the molecular and empirical formulae of the compound shown. [2] OH O Molecular formula Empirical formula
  9. Summer 2023, Unit 4, Q1 (1 mark): Give the structure of an unsaturated aldehyde of molecular formula C4H6O. [1]
  10. Summer 2023, Unit 4, Q8(e) (2 marks): The solubility of unsaturated carboxylic acids in water decreases as the chain length increases. Number of carbon atoms Solubility in water at 25 °C / g dm−3 in
  11. Summer 2023, Unit 4, Q12(c)(i) (1 mark): Give the systematic name of this halogenoalkane. [1]
  12. Summer 2023, AS Unit 2, Q1 (1 mark): Give the molecular formula of the compound shown. [1] O OH Molecular formula
  13. Summer 2023, AS Unit 2, Q4 (2 marks): Cyclobutane is a cyclic hydrocarbon whose structure is shown. H H H C C H H C C H H H Draw the structures of two structural isomers of this compound. [2]
  14. Summer 2023, AS Unit 2, Q13(a)(i) (3 marks): Use the diagram below to show the intermolecular forces that allow ethane-1,2-diol to dissolve in water. [3] H H H C C O O H H H
  15. Summer 2023, AS Unit 2, Q13(a)(ii) (1 mark): Suggest a reason why the addition of ethane-1,2-diol lowers the freezing temperature of water. [1]
  16. Summer 2022, Unit 4, Q7(a)(ii) (1 mark): Give the structure of an isomer that is both a ketone and a secondary alcohol. [1]
  17. Summer 2022, Unit 4, Q12(b)(iv) (1 mark): Fats and oils are esters of carboxylic acids and glycerol. Give the systematic name of glycerol (seen in part (iii) above). [1]
  18. Summer 2022, AS Unit 2, Q6(a)(i) (1 mark): Circle the species that represents the electrophile. [1]
  19. Summer 2022, AS Unit 2, Q6(a)(ii) (1 mark): Name the type of bond fission that takes place in the H Br bond in the first step of the mechanism. [1]
  20. Summer 2022, AS Unit 2, Q7(a)(i) (1 mark): Give the meaning of the term ‘structural isomer’. [1]
  21. Summer 2022, AS Unit 2, Q7(a)(ii) (3 marks): Complete the table below showing important information about the isomers of C6H14. [3] Boiling Name Shortened structural formula Skeletal formula temperature /
  22. Summer 2022, AS Unit 2, Q7(a)(iii) (2 marks): State the relationship between the boiling temperature and the carbon chain length. Explain this relationship in terms of intermolecular forces. [2]
  23. Summer 2019, Unit 4, Q7(a) (1 mark): Draw the displayed formula of another structural isomer of formula C3H4Cl2. [1]
  24. Summer 2019, AS Unit 2, Q1 (1 mark): Draw the skeletal formula of 2-bromo-3-methylbutane. [1]
  25. Summer 2019, AS Unit 2, Q10(a) (6 marks): Students were discussing the reactivity of organic compounds. One said that reactivity was due to dipoles produced by differences in electronegativity. Show tha
  26. Summer 2018, Unit 4, Q6(a)(i) (1 mark): Give the molecular formula of oct-1-en-3-ol. [1]
  27. Summer 2018, Unit 4, Q6(e)(i) (2 marks): Write the skeletal formula of this compound. [2]
  28. Summer 2018, Unit 4, Q9(b)(iv) (1 mark): The boiling temperatures of compounds A, B and C in part (iii) are shown in the table. O Boiling R in CH3 C Compound Name temperature / °C O R CH2CHCH2CH3 A 2-m
  29. Summer 2018, AS Unit 2, Q2 (1 mark): Draw the skeletal formula of 3-chloro-2,2-dimethylpentane. [1]
  30. Summer 2018, AS Unit 2, Q3 (2 marks): Explain why ethanol is soluble in water but ethane is not. [2]
  31. Summer 2017, AS Unit 2, Q1(a) (1 mark): Draw the displayed formula of (E)-pent-2-ene. [1]
  32. Summer 2017, AS Unit 2, Q1(b) (1 mark): Draw the skeletal formula of 3-chlorohex-1-ene. [1]
  33. Summer 2017, AS Unit 2, Q2 (1 mark): State the molecular formula of a straight-chained saturated halogenoalkane whose molecules each contain 50 carbon atoms and 2 chlorine atoms. [1]
  34. Summer 2016, AS Unit 2, Q1(a) (1 mark): Name the compound whose formula is shown below. [1] CH3 H COOH H C C C C CH 3 3 H Cl H
  35. Summer 2016, AS Unit 2, Q1(b) (1 mark): Draw the skeletal formula of the compound shown in (a). [1]
  36. Summer 2016, AS Unit 2, Q11(c)(ii) (2 marks): Draw the displayed formulae of two possible isomers of A. [2]

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