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OCR A‑Level Chemistry A questions by topic

Every question from every OCR A-Level Chemistry A paper, 2016–2025, part by part. Filter by topic, paper or year, open the mark scheme under any question, and download a set as a PDF.

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Year 1 · AS

Year 2 · A‑Level only

Calculations

1,820 questions

  1. Q1

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 1: The table shows the number of protons and neutrons in four different atoms. Atom Number of protons Number of neutrons W 17 18 X 18 18 Y 19 18 Z 18 19 Which two

  2. Q2

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 2: 11.895 g of hydrated cobalt(II) chloride, CoCl 2•xH2O, is heated to remove the water of crystallisation. After heating to constant mass, the mass of the anhydro

  3. Q3

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 3: The diagram shows the Born-Haber cycle for sodium oxide, Na2O. 2Na+(g) + O2–(g) 2Na+(g) + O(g) + 2e– 2Na+(g) + O–(g) + e– 2Na(g) + O(g) 2Na(g) + ½O2(g) 2Na(s) +

  4. Q4

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 4: What volume, in cm3, of 0.250 mol dm–3 barium hydroxide solution is required to exactly 4 neutralise 25.0 cm3 of 0.115 mol dm–3 hydrochloric acid? Ba(OH)2(aq) +

  5. Q5

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 5: The graph shows the volume of hydrogen released over time in a chemical reaction. 100 90 80 70 60 Volume of hydrogen 50 / cm3 40 30 20 10 0 0 20 40 60 80 100 Ti

  6. Q6

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 6: Methane reacts with oxygen as shown in the equation: CO2(g) + 2H2O(g) ΔrH = –730 kJ mol–1 CH4(g) + 2O2(g) The table shows some bond enthalpies. Bond O–H O=O C=O

  7. Q7

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 7: The table below shows the boiling points of some hydrogen halides. Hydrogen halide Boiling point / K HCl 188 HBr 206 238 HI What is the best explanation for the

  8. Q8

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 8: The burette readings from an experiment are shown: Final reading / cm3 29.35 Initial reading / cm3 2.60 The burette has an uncertainty of ±0.05 cm3. What is the

  9. Q9

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 9: Hydrogen reacts with iodine monochloride, ICl , as shown in the equation: H2 + 2ICl 2HCl + I2 The mechanism for the reaction is: H2 + ICl HCl + HI slow step HI

  10. Q10

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 10: The overall equation for a hydrogen–oxygen fuel cell is: H2(g) + 1 2O2(g) H2O(l) The half-equation at the negative electrode is: H2(g) + 2OH–(aq) 2H2O(l) + 2e–

  11. Q11

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 11: Two redox systems are shown below. Mg2+(aq) + 2e– E ɵ= – 2.37 V Mg(s) Pb2+(aq) + 2e– E ɵ = – 0.13 V Pb(s) Which species is the strongest reducing agent? Mg2+(aq

  12. Q12

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 12: The rate constant, k, for a first order reaction is 6.19 × 10–3 s–1. What is the half-life, in s, for the reaction? 4.29 × 10–3 A B 49 C 112 D 323 Your answer [

  13. Q13

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 13: A mixture of ethanoic acid and ethanol is left to reach equilibrium. A student determines the amount of ethanoic acid remaining in the equilibrium mixture by ti

  14. Q14

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 14: Barium is in Group 2 of the periodic table. Which statement(s) about barium is / are correct? 1 Its outer shell electrons are in an s-orbital. 2 It reacts more

  15. Q15

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 15: Chromium forms the complex ions [Cr(NH3)6]3+ and [Cr(OH)6]3–. Which statement(s) about the complexes is / are correct? 1 Chromium is in the same oxidation state

  16. Q16(a)(i)

    June 2025 · Paper 1

    2 marks
    The whole paper ↗
    June 2025 Paper 1, question 16(a)(i): Complete the graph to show approximate melting points for P, S, Cl and Ar. [2]

  17. Q16(a)(ii)

    June 2025 · Paper 1

    3 marks
    The whole paper ↗
    June 2025 Paper 1, question 16(a)(ii): Explain why silicon has a higher melting point than aluminium. Use ideas about structure and bonding in your answer. [3]

  18. Q16(b)(i)

    June 2025 · Paper 1

    1 mark
    The whole paper ↗
    June 2025 Paper 1, question 16(b)(i): Write an equation to represent the first ionisation energy of sulfur. Include state symbols. [1]

  19. Q16(b)(ii)

    June 2025 · Paper 1

    2 marks
    The whole paper ↗
    June 2025 Paper 1, question 16(b)(ii): The table shows that there is a general increase in first ionisation energies across Period 3, but that this trend is not followed by phosphorus to sulfur. Expl

  20. Q16(c)

    June 2025 · Paper 1

    3 marks
    The whole paper ↗
    June 2025 Paper 1, question 16(c): A student adds an aqueous solution of bromine, Br2(aq), to two test tubes. The student adds aqueous sodium iodide, NaI(aq), to the Br2(aq) in one test tube, and

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