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Instrumental analysis: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 2.8 Instrumental analysis, 2016–2025, with its mark scheme and examiner’s report.

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1,204 questions

  1. Q9(a)(vi)

    Summer 2025 · Unit 4

    3 marks4.6 Amines2.8 Instrumental analysis
    The whole paper ↗
    Summer 2025 Unit 4, question 9(a)(vi): Benzamide, C6H5CONH2, undergoes the Hofmann degradation reaction. This reaction produces an organic nitrogen-containing compound Z, that contains one carbon ato

  2. Q9(a)

    Summer 2025 · AS Unit 2

    10 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2025 AS Unit 2, question 9(a): Compound A contains carbon, hydrogen and oxygen only. Elemental analysis of compound A indicates that it is composed of 68.09 % carbon and 18.16 % oxygen by mas

  3. Q3

    Summer 2024 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 3: Four isomers of formula C6H12O2 are given below. CH2OH H2C CH CH CH2OCH3 OCH3 O compound D compound E H2C CH CH O CH2CH2CH3 CH3CH2CH2CH2 C CH2 OH OH O compound

  4. Q5

    Summer 2024 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2024 Unit 4, question 5: The structure of paraldehyde is shown below. O O O Explain what would be seen in the 13C NMR spectrum of this compound. References to the positions of the chemi

  5. Q11(b)

    Summer 2024 · AS Unit 2

    8 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2024 AS Unit 2, question 11(b): A simplified form of the mass spectrum, the 13C NMR spectrum and the low resolution 1H NMR spectrum of halogenoalkane X are shown. Mass Abundance spectrum 0 20

  6. Q11(b)(ii)

    Summer 2023 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2023 Unit 4, question 11(b)(ii): Under suitable conditions, aminoethanoic acid condenses to give diketopiperazine. H H O C C H N N H C C H O H I. The mass spectrum of diketopiperazine shows a m

  7. Q11(a)

    Summer 2023 · AS Unit 2

    8 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2023 AS Unit 2, question 11(a): Compound X contains carbon, hydrogen and oxygen only. It has no reaction with acidified potassium dichromate. Simplified versions of its mass spectrum, IR spect

  8. Q11(b)

    Summer 2023 · AS Unit 2

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2023 AS Unit 2, question 11(b): the compound you identified in part (a). You should indicate where you would expect to see peaks and the relative intensities of the peaks. [2] 11 10 9 8 7 6 5

  9. Q13(b)(iv)

    Summer 2023 · AS Unit 2

    1 mark2.8 Instrumental analysis
    The whole paper ↗
    Summer 2023 AS Unit 2, question 13(b)(iv): A sample of the reacting mixture was taken during the reflux process and a mass spectrum was produced. One of the peaks recorded was at m/z 58 Suggest the ident

  10. Q1

    Summer 2022 · Unit 4

    1 mark2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 1: A hydrocarbon is either cyclopentane or pent-1-ene. Use the Data Booklet to choose a characteristic infrared absorption that will positively identify the compou

  11. Q4

    Summer 2022 · Unit 4

    1 mark2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 4: Give the structure of a compound of molecular formula C4H8Br2 whose low resolution 1H NMR 4 spectrum consists of three peaks. [1]

  12. Q8(a)(ii)

    Summer 2022 · Unit 4

    6 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 8(a)(ii): Cyclohexane, the product from the first stage, is then catalytically oxidised using air. This results in KA (a mixture of cyclohexanol and cyclohexanone). The m

  13. Q10(b)

    Summer 2022 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 10(b): The absorption spectrum of compound G shows a maximum absorption at 450 nm. Light energy measured in kJ mol–1 (E) is related to wavelength (λ) by the equation E

  14. Q11(c)

    Summer 2022 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 11(c): Hexa-2,4-diene is one of the important products that can be produced from butane-1,4-dioic acid. H CH3 C C H H C C H3C H hexa-2,4-diene Use the formula to help

  15. Q12(a)(i)

    Summer 2022 · Unit 4

    1 mark2.8 Instrumental analysis
    The whole paper ↗
    Summer 2022 Unit 4, question 12(a)(i): The ultraviolet absorption spectrum of compound A is shown below. Absorbance 200 300 400 Wavelength / nm Ultraviolet radiation is divided into three regions. Re

  16. Q10(c)(iii)

    Summer 2019 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2019 Unit 4, question 10(c)(iii): When ethanamide is heated with a dehydrating agent the organic product is ethanenitrile. Use the Data Booklet to state and explain how characteristic infrared a

  17. Q11(a)

    Summer 2019 · AS Unit 2

    10 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2019 AS Unit 2, question 11(a): Compound X contains only carbon, hydrogen and oxygen. On analysis X was found to contain 40.0 % carbon and 6.67 % hydrogen by mass. A simplified form of the mas

  18. Q11(b)(i)

    Summer 2019 · AS Unit 2

    3 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2019 AS Unit 2, question 11(b)(i): from ethyl ethanoate. O carbon atom A CH3 C OCH2CH3 Label the diagram to show the species causing each peak. The peak caused by carbon atom A is already include

  19. Q11(b)(ii)

    Summer 2019 · AS Unit 2

    1 mark2.8 Instrumental analysis
    The whole paper ↗
    Summer 2019 AS Unit 2, question 11(b)(ii): A student said that valuable information about the nature of a sample being analysed could be obtained from the peak heights in both the 13C and 1H NMR spectra.

  20. Q6(d)

    Summer 2018 · Unit 4

    2 marks2.8 Instrumental analysis
    The whole paper ↗
    Summer 2018 Unit 4, question 6(d): The mass spectrum of octane-2,3-dione (Mr 142) shows fragmentation peaks at m/z 99, 71 and 43 O octane-2,3-dione O Identify the species responsible for these pe
All 27 questions on Instrumental analysis, as a list
  1. Summer 2025, Unit 4, Q9(a)(vi) (3 marks): Benzamide, C6H5CONH2, undergoes the Hofmann degradation reaction. This reaction produces an organic nitrogen-containing compound Z, that contains one carbon ato
  2. Summer 2025, AS Unit 2, Q9(a) (10 marks): Compound A contains carbon, hydrogen and oxygen only. Elemental analysis of compound A indicates that it is composed of 68.09 % carbon and 18.16 % oxygen by mas
  3. Summer 2024, Unit 4, Q3 (2 marks): Four isomers of formula C6H12O2 are given below. CH2OH H2C CH CH CH2OCH3 OCH3 O compound D compound E H2C CH CH O CH2CH2CH3 CH3CH2CH2CH2 C CH2 OH OH O compound
  4. Summer 2024, Unit 4, Q5 (2 marks): The structure of paraldehyde is shown below. O O O Explain what would be seen in the 13C NMR spectrum of this compound. References to the positions of the chemi
  5. Summer 2024, AS Unit 2, Q11(b) (8 marks): A simplified form of the mass spectrum, the 13C NMR spectrum and the low resolution 1H NMR spectrum of halogenoalkane X are shown. Mass Abundance spectrum 0 20
  6. Summer 2023, Unit 4, Q11(b)(ii) (2 marks): Under suitable conditions, aminoethanoic acid condenses to give diketopiperazine. H H O C C H N N H C C H O H I. The mass spectrum of diketopiperazine shows a m
  7. Summer 2023, AS Unit 2, Q11(a) (8 marks): Compound X contains carbon, hydrogen and oxygen only. It has no reaction with acidified potassium dichromate. Simplified versions of its mass spectrum, IR spect
  8. Summer 2023, AS Unit 2, Q11(b) (2 marks): the compound you identified in part (a). You should indicate where you would expect to see peaks and the relative intensities of the peaks. [2] 11 10 9 8 7 6 5
  9. Summer 2023, AS Unit 2, Q13(b)(iv) (1 mark): A sample of the reacting mixture was taken during the reflux process and a mass spectrum was produced. One of the peaks recorded was at m/z 58 Suggest the ident
  10. Summer 2022, Unit 4, Q1 (1 mark): A hydrocarbon is either cyclopentane or pent-1-ene. Use the Data Booklet to choose a characteristic infrared absorption that will positively identify the compou
  11. Summer 2022, Unit 4, Q4 (1 mark): Give the structure of a compound of molecular formula C4H8Br2 whose low resolution 1H NMR 4 spectrum consists of three peaks. [1]
  12. Summer 2022, Unit 4, Q8(a)(ii) (6 marks): Cyclohexane, the product from the first stage, is then catalytically oxidised using air. This results in KA (a mixture of cyclohexanol and cyclohexanone). The m
  13. Summer 2022, Unit 4, Q10(b) (2 marks): The absorption spectrum of compound G shows a maximum absorption at 450 nm. Light energy measured in kJ mol–1 (E) is related to wavelength (λ) by the equation E
  14. Summer 2022, Unit 4, Q11(c) (2 marks): Hexa-2,4-diene is one of the important products that can be produced from butane-1,4-dioic acid. H CH3 C C H H C C H3C H hexa-2,4-diene Use the formula to help
  15. Summer 2022, Unit 4, Q12(a)(i) (1 mark): The ultraviolet absorption spectrum of compound A is shown below. Absorbance 200 300 400 Wavelength / nm Ultraviolet radiation is divided into three regions. Re
  16. Summer 2019, Unit 4, Q10(c)(iii) (2 marks): When ethanamide is heated with a dehydrating agent the organic product is ethanenitrile. Use the Data Booklet to state and explain how characteristic infrared a
  17. Summer 2019, AS Unit 2, Q11(a) (10 marks): Compound X contains only carbon, hydrogen and oxygen. On analysis X was found to contain 40.0 % carbon and 6.67 % hydrogen by mass. A simplified form of the mas
  18. Summer 2019, AS Unit 2, Q11(b)(i) (3 marks): from ethyl ethanoate. O carbon atom A CH3 C OCH2CH3 Label the diagram to show the species causing each peak. The peak caused by carbon atom A is already include
  19. Summer 2019, AS Unit 2, Q11(b)(ii) (1 mark): A student said that valuable information about the nature of a sample being analysed could be obtained from the peak heights in both the 13C and 1H NMR spectra.
  20. Summer 2018, Unit 4, Q6(d) (2 marks): The mass spectrum of octane-2,3-dione (Mr 142) shows fragmentation peaks at m/z 99, 71 and 43 O octane-2,3-dione O Identify the species responsible for these pe
  21. Summer 2018, Unit 4, Q7(e) (3 marks): Under suitable conditions diphenylmethanone oxime undergoes a rearrangement. C6H5 O C N OH C6H5 C N C6H5 C6H5 H diphenylmethanone oxime N-phenylbenzamide Descri
  22. Summer 2018, AS Unit 2, Q8(a) (2 marks): State an instrumental method by which the sample could be analysed. Explain how this would show that chlorination had occurred. [2]
  23. Summer 2018, AS Unit 2, Q11(a) (10 marks): Use all the data given to find the structure of compound X. Explain what information can be found from each piece of data. [10] Structure of X
  24. Summer 2017, Unit 4, Q9(a)(ii) (1 mark): DEET is a colourless liquid in white light. Explain, in terms of the electromagnetic spectrum, why DEET is colourless. [1]
  25. Summer 2017, Unit 4, Q9(a)(iii) (2 marks): The mass spectrum of DEET shows a molecular ion at m/z 191. It also shows a prominent peak at m/z 91 Suggest a formula for the fragment that is lost so that the
  26. Summer 2017, AS Unit 2, Q8(b) (6 marks): Compound Y is a halogenoalkane. A simplified form of the IR spectrum, the mass spectrum, the 13C NMR spectrum and the low resolution 1H NMR spectrum of Y are sh
  27. Summer 2016, AS Unit 2, Q12 (10 marks): Chemists are investigating an unknown compound X. They obtain information from a variety of sources. Compound X contains 61.2 % carbon, 6.1 % hydrogen and 32.7

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