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Formulae and equations: WJEC A‑Level Chemistry questions

Every WJEC A-Level Chemistry exam question on 1.1 Formulae and equations, 2016–2025, with its mark scheme and examiner’s report.

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1,204 questions

  1. Q7

    Summer 2025 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2025 AS Unit 1, question 7: –. 7 The hydrogencarbonate anion has the formula HCO3 Write the formula of magnesium hydrogencarbonate. [1]

  2. Q11(d)

    Summer 2025 · AS Unit 1

    2 marks1.1 Formulae and equations
    The whole paper ↗
    Summer 2025 AS Unit 1, question 11(d): Chlorine can react with water to produce hydrogen chloride and oxygen. 2Cl2 + 2H2O 4HCl + O2 Explain why this reaction is classified as a redox reaction. [2]

  3. Q12(b)

    Summer 2025 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2025 AS Unit 1, question 12(b): Lithium hydride, LiH, reacts with aluminium chloride, AlCl3, to form lithium aluminium hydride, LiAlH4, and lithium chloride. Write the equation for this reacti

  4. Q12(c)(ii)

    Summer 2025 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2025 AS Unit 1, question 12(c)(ii): One other product is formed. Determine the formula of this product by writing an equation for the decomposition reaction. [1]

  5. Q5

    Summer 2024 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2024 AS Unit 1, question 5: Magnesium nitrate decomposes when heated to form magnesium oxide, nitrogen dioxide and oxygen. Balance the equation for this reaction. [1] 2 Mg(NO3)2 MgO + NO2

  6. Q10(b)(i)

    Summer 2023 · Unit 3

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 Unit 3, question 10(b)(i): Write an equation for this process. [1]

  7. Q10(b)(ii)

    Summer 2023 · Unit 3

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 Unit 3, question 10(b)(ii): Show that the xenon is oxidised in the process. [1]

  8. Q3

    Summer 2023 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 AS Unit 1, question 3: Give the oxidation number of rhenium in ReOCl4. [1]

  9. Q7(b)(i)

    Summer 2023 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 AS Unit 1, question 7(b)(i): Balance the equation. [1]

  10. Q7(b)(ii)

    Summer 2023 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 AS Unit 1, question 7(b)(ii): Explain why this reaction is described as a redox process. [1]

  11. Q11(a)(v)

    Summer 2023 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2023 AS Unit 1, question 11(a)(v): Write an ionic equation for the precipitation of silver chromate(VI). [1]

  12. Q9(b)

    Summer 2022 · Unit 4

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2022 Unit 4, question 9(b): 2,4-Dinitroanisole can also be made by the nitration of anisole. OCH3 NO2 NO2 This compound has been used as an explosive. On detonation, it gives carbon, carbo

  13. Q8(b)(ii)

    Summer 2022 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2022 AS Unit 1, question 8(b)(ii): Write an ionic equation, including state symbols, for one of the above observations. [1]

  14. Q11(a)(i)

    Summer 2022 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2022 AS Unit 1, question 11(a)(i): State the oxidation state of arsenic in As2O3. [1]

  15. Q11(a)(ii)

    Summer 2022 · AS Unit 1

    2 marks1.1 Formulae and equations
    The whole paper ↗
    Summer 2022 AS Unit 1, question 11(a)(ii): Give a balanced chemical equation for the industrial production of As2O3 from FeAsS. [2]

  16. Q5

    Summer 2019 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2019 AS Unit 1, question 5: Give the oxidation number of vanadium in VOCl3. [1]

  17. Q6

    Summer 2019 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2019 AS Unit 1, question 6: Phosphoric acid has the formula H3PO4. Write the formula of magnesium phosphate. [1]

  18. Q4(a)

    Summer 2018 · AS Unit 1

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2018 AS Unit 1, question 4(a): Balance the equation. [1]

  19. Q9(f)(ii)

    Summer 2018 · AS Unit 1

    2 marks1.1 Formulae and equations
    The whole paper ↗
    Summer 2018 AS Unit 1, question 9(f)(ii): When hydrochloric acid is heated with MnO2 it reacts according to the following equation. MnO2(s) + 4HCl(aq) MnCl2(aq) + Cl2(g) + 2H2O(l) Explain why this can b

  20. Q10(a)

    Summer 2017 · Unit 3

    1 mark1.1 Formulae and equations
    The whole paper ↗
    Summer 2017 Unit 3, question 10(a): Show that this is a redox reaction. [1]
All 28 questions on Formulae and equations, as a list
  1. Summer 2025, AS Unit 1, Q7 (1 mark): –. 7 The hydrogencarbonate anion has the formula HCO3 Write the formula of magnesium hydrogencarbonate. [1]
  2. Summer 2025, AS Unit 1, Q11(d) (2 marks): Chlorine can react with water to produce hydrogen chloride and oxygen. 2Cl2 + 2H2O 4HCl + O2 Explain why this reaction is classified as a redox reaction. [2]
  3. Summer 2025, AS Unit 1, Q12(b) (1 mark): Lithium hydride, LiH, reacts with aluminium chloride, AlCl3, to form lithium aluminium hydride, LiAlH4, and lithium chloride. Write the equation for this reacti
  4. Summer 2025, AS Unit 1, Q12(c)(ii) (1 mark): One other product is formed. Determine the formula of this product by writing an equation for the decomposition reaction. [1]
  5. Summer 2024, AS Unit 1, Q5 (1 mark): Magnesium nitrate decomposes when heated to form magnesium oxide, nitrogen dioxide and oxygen. Balance the equation for this reaction. [1] 2 Mg(NO3)2 MgO + NO2
  6. Summer 2023, Unit 3, Q10(b)(i) (1 mark): Write an equation for this process. [1]
  7. Summer 2023, Unit 3, Q10(b)(ii) (1 mark): Show that the xenon is oxidised in the process. [1]
  8. Summer 2023, AS Unit 1, Q3 (1 mark): Give the oxidation number of rhenium in ReOCl4. [1]
  9. Summer 2023, AS Unit 1, Q7(b)(i) (1 mark): Balance the equation. [1]
  10. Summer 2023, AS Unit 1, Q7(b)(ii) (1 mark): Explain why this reaction is described as a redox process. [1]
  11. Summer 2023, AS Unit 1, Q11(a)(v) (1 mark): Write an ionic equation for the precipitation of silver chromate(VI). [1]
  12. Summer 2022, Unit 4, Q9(b) (1 mark): 2,4-Dinitroanisole can also be made by the nitration of anisole. OCH3 NO2 NO2 This compound has been used as an explosive. On detonation, it gives carbon, carbo
  13. Summer 2022, AS Unit 1, Q8(b)(ii) (1 mark): Write an ionic equation, including state symbols, for one of the above observations. [1]
  14. Summer 2022, AS Unit 1, Q11(a)(i) (1 mark): State the oxidation state of arsenic in As2O3. [1]
  15. Summer 2022, AS Unit 1, Q11(a)(ii) (2 marks): Give a balanced chemical equation for the industrial production of As2O3 from FeAsS. [2]
  16. Summer 2019, AS Unit 1, Q5 (1 mark): Give the oxidation number of vanadium in VOCl3. [1]
  17. Summer 2019, AS Unit 1, Q6 (1 mark): Phosphoric acid has the formula H3PO4. Write the formula of magnesium phosphate. [1]
  18. Summer 2018, AS Unit 1, Q4(a) (1 mark): Balance the equation. [1]
  19. Summer 2018, AS Unit 1, Q9(f)(ii) (2 marks): When hydrochloric acid is heated with MnO2 it reacts according to the following equation. MnO2(s) + 4HCl(aq) MnCl2(aq) + Cl2(g) + 2H2O(l) Explain why this can b
  20. Summer 2017, Unit 3, Q10(a) (1 mark): Show that this is a redox reaction. [1]
  21. Summer 2017, AS Unit 1, Q8(a)(i) (1 mark): Balance the equation above. [1]
  22. Summer 2017, AS Unit 1, Q8(a)(iv) (3 marks): During the smelting Cu2S is produced. This is collected and blown with air to produce copper. Cu2S + O2 2Cu + SO2 This is classified as a redox reaction. Use ox
  23. Summer 2017, AS Unit 1, Q9(c)(i) (1 mark): Write the ionic equation, including state symbols, for this precipitation reaction. [1]
  24. Summer 2017, AS Unit 1, Q9(c)(ii) (1 mark): State why the aqueous barium chloride was added in excess. [1]
  25. Summer 2016, AS Unit 1, Q2 (1 mark): 2–. 2 Give the oxidation number of molybdenum in the ion MoO4 [1]
  26. Summer 2016, AS Unit 1, Q8(a) (2 marks): Iron(III) oxide, Fe2O3, and carbon monoxide react to give iron and carbon dioxide. Give the equation for this reaction. Explain why it is described as a redox p
  27. Summer 2016, AS Unit 1, Q9(a)(i) (1 mark): Balance the equation. [1] C12H22O11 + [O] (COOH)2 + H2O
  28. Summer 2016, AS Unit 1, Q9(c)(i) (2 marks): Suggest how Gareth would know when enough calcium chloride solution had been added to react with all of the potassium oxalate present. [2]

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