Skip to content
Try on iPad

Nuclear decay: WJEC A‑Level Physics questions

Every WJEC A-Level Physics exam question on 3.5 Nuclear decay, 2016–2025, with its mark scheme and examiner’s report.

Find questions1,173
Calculations

1,173 questions

  1. Q3(a)

    Summer 2025 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2025 Unit 3, question 3(a): Elliot states that the nucleus that emits a β– as it decays is nucleus X. Meg states that the nucleus that emits a β– as it decays is nucleus Y. Determine who i

  2. Q3(b)

    Summer 2025 · Unit 3

    1 mark3.5 Nuclear decay
    The whole paper ↗
    Summer 2025 Unit 3, question 3(b): Define the half-life, T1 , of a radioactive substance. [1] 2

  3. Q3(c)

    Summer 2025 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2025 Unit 3, question 3(c): Starting with the equation: A = A0e–λt Show, in clear steps, that: = ln 2 T1 λ [3] 2

  4. Q3(d)

    Summer 2025 · Unit 3

    4 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2025 Unit 3, question 3(d): The activity of a radioactive nuclide drops to 82% of its initial value in 730 years. Calculate its half-life. [4]

  5. Q3(e)

    Summer 2025 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2025 Unit 3, question 3(e): Ella carried out an experiment to model radioactive decay. She used a large number of identical 6-sided dice. All dice had 2 sides painted black. She rolled the

  6. Q3(a)

    Summer 2024 · Unit 3

    6 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2024 Unit 3, question 3(a): Describe an experiment to investigate the variation of intensity of gamma radiation with the distance from a source. Consider the experimental set-up, data coll

  7. Q6(a)

    Summer 2024 · Unit 3

    4 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2024 Unit 3, question 6(a): Estimate the age of the boat. [4]

  8. Q6(b)

    Summer 2024 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2024 Unit 3, question 6(b): Calculate the activity of the after 7000 years as a percentage of its original activity. 6 [3]

  9. Q3(a)

    Summer 2023 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2023 Unit 3, question 3(a): State what is meant by alpha emission. [2]

  10. Q3(b)

    Summer 2023 · Unit 3

    4 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2023 Unit 3, question 3(b): Americium-241 has a half-life of 432 years. Determine the percentage decrease in the activity of the element after 30 years. [4]

  11. Q3(c)

    Summer 2023 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2023 Unit 3, question 3(c): A builder is asked to install a smoke detector. He researches smoke detectors and finds that the radioactive source in the detector emits alpha particles. He de

  12. Q3(d)

    Summer 2023 · Unit 3

    6 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2023 Unit 3, question 3(d): Describe how alpha, beta and gamma radiation can be distinguished: • by using different absorbers • by using an electric field or a magnetic field. [6 QER]

  13. Q1(a)(i)

    Summer 2022 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 1(a)(i): Explain what is meant by the activity of a radioactive source and give its unit. [2]

  14. Q1(a)(ii)

    Summer 2022 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 1(a)(ii): radon to decay to 20 % of its initial activity. [3]

  15. Q1(a)(iii)

    Summer 2022 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 1(a)(iii): Discuss the extent to which alpha particles are a risk to the human body. [3]

  16. Q5(a)(i)

    Summer 2022 · Unit 3

    1 mark3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 5(a)(i): Suggest why a thin aluminium plate is placed near the source. [1]

  17. Q5(a)(ii)

    Summer 2022 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 5(a)(ii): Explain why readings are taken without the source, at the start and at the end of the experiment. [2]

  18. Q5(b)

    Summer 2022 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 5(b): At each distance, r, the counts were measured over one minute intervals three times. The uncertainty in r is ± 0.005 m. The measurements are recorded in the tab

  19. Q5(c)(i)

    Summer 2022 · Unit 3

    2 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 5(c)(i): The student subtracts the mean count without the source from the mean count for each distance to obtain the corrected mean count, N. She also determines the unc

  20. Q5(c)(ii)

    Summer 2022 · Unit 3

    3 marks3.5 Nuclear decay
    The whole paper ↗
    Summer 2022 Unit 3, question 5(c)(ii): Plot a graph of the corrected mean count, N, against distance, r. Error bars are not required. [3] Corrected mean count, N 800 600 400 200 0 0.000 0.200 0.400 0
All 33 questions on Nuclear decay, as a list
  1. Summer 2025, Unit 3, Q3(a) (3 marks): Elliot states that the nucleus that emits a β– as it decays is nucleus X. Meg states that the nucleus that emits a β– as it decays is nucleus Y. Determine who i
  2. Summer 2025, Unit 3, Q3(b) (1 mark): Define the half-life, T1 , of a radioactive substance. [1] 2
  3. Summer 2025, Unit 3, Q3(c) (3 marks): Starting with the equation: A = A0e–λt Show, in clear steps, that: = ln 2 T1 λ [3] 2
  4. Summer 2025, Unit 3, Q3(d) (4 marks): The activity of a radioactive nuclide drops to 82% of its initial value in 730 years. Calculate its half-life. [4]
  5. Summer 2025, Unit 3, Q3(e) (3 marks): Ella carried out an experiment to model radioactive decay. She used a large number of identical 6-sided dice. All dice had 2 sides painted black. She rolled the
  6. Summer 2024, Unit 3, Q3(a) (6 marks): Describe an experiment to investigate the variation of intensity of gamma radiation with the distance from a source. Consider the experimental set-up, data coll
  7. Summer 2024, Unit 3, Q6(a) (4 marks): Estimate the age of the boat. [4]
  8. Summer 2024, Unit 3, Q6(b) (3 marks): Calculate the activity of the after 7000 years as a percentage of its original activity. 6 [3]
  9. Summer 2023, Unit 3, Q3(a) (2 marks): State what is meant by alpha emission. [2]
  10. Summer 2023, Unit 3, Q3(b) (4 marks): Americium-241 has a half-life of 432 years. Determine the percentage decrease in the activity of the element after 30 years. [4]
  11. Summer 2023, Unit 3, Q3(c) (2 marks): A builder is asked to install a smoke detector. He researches smoke detectors and finds that the radioactive source in the detector emits alpha particles. He de
  12. Summer 2023, Unit 3, Q3(d) (6 marks): Describe how alpha, beta and gamma radiation can be distinguished: • by using different absorbers • by using an electric field or a magnetic field. [6 QER]
  13. Summer 2022, Unit 3, Q1(a)(i) (2 marks): Explain what is meant by the activity of a radioactive source and give its unit. [2]
  14. Summer 2022, Unit 3, Q1(a)(ii) (3 marks): radon to decay to 20 % of its initial activity. [3]
  15. Summer 2022, Unit 3, Q1(a)(iii) (3 marks): Discuss the extent to which alpha particles are a risk to the human body. [3]
  16. Summer 2022, Unit 3, Q5(a)(i) (1 mark): Suggest why a thin aluminium plate is placed near the source. [1]
  17. Summer 2022, Unit 3, Q5(a)(ii) (2 marks): Explain why readings are taken without the source, at the start and at the end of the experiment. [2]
  18. Summer 2022, Unit 3, Q5(b) (2 marks): At each distance, r, the counts were measured over one minute intervals three times. The uncertainty in r is ± 0.005 m. The measurements are recorded in the tab
  19. Summer 2022, Unit 3, Q5(c)(i) (2 marks): The student subtracts the mean count without the source from the mean count for each distance to obtain the corrected mean count, N. She also determines the unc
  20. Summer 2022, Unit 3, Q5(c)(ii) (3 marks): Plot a graph of the corrected mean count, N, against distance, r. Error bars are not required. [3] Corrected mean count, N 800 600 400 200 0 0.000 0.200 0.400 0
  21. Summer 2022, Unit 3, Q5(c)(iii) (1 mark): The student claims that error bars may be shown on the graph for the corrected mean count, but not the distance. Justify her claim. Calculations are not require
  22. Summer 2022, Unit 3, Q5(d) (3 marks): Her friend suggests using a logarithmic graph. She calculates the logarithmic values in the table below. ln r ln N Distance, r / m 1.000 0.00 4.63 0.800 –0.22 5
  23. Summer 2022, Unit 3, Q5(e)(i) (3 marks): Starting with intensity: justify how the logarithmic graph can be used to rn determine n. [3]
  24. Summer 2022, Unit 3, Q5(e)(ii) (4 marks): Use the maximum and minimum gradients to determine n and the absolute uncertainty in its value. [4] SECTION B Answer all questions.
  25. Summer 2019, Unit 3, Q6(a)(i) (1 mark): Complete the following decay equations.
  26. Summer 2019, Unit 3, Q6(a)(ii) (1 mark): [1] 38
  27. Summer 2019, Unit 3, Q6(c)(i) (1 mark): If the student throws one of the dice, what is the probability of the tetrahedron landing on the black face? [1]
  28. Summer 2019, Unit 3, Q6(c)(ii) (6 marks): The student then throws all dice and counts and discards those that landed on the black face. The remaining dice are thrown again and the process is repeated mu
  29. Summer 2018, Unit 3, Q5 (8 marks): (a) Radon gas decays by emitting α-particles. It has a half-life of 3.8 days. Calculate the 5 percentage reduction in the activity of a sample of radon after 12
  30. Summer 2017, Unit 3, Q1(a) (4 marks): Describe an experiment that uses various absorbers to identify the type(s) of radiations emitted by a radioactive sample. Justify all steps in the experiment. [
  31. Summer 2017, Unit 3, Q1(b)(i) (2 marks): the decay constant; [2]
  32. Summer 2017, Unit 3, Q1(b)(ii) (2 marks): the activity of the sample after 57.0 days in terms of A0; [2]
  33. Summer 2017, Unit 3, Q1(b)(iii) (3 marks): the percentage decrease in the number of nuclei in the sample after 57.0 days. [3]

Questions, mark schemes and examiner’s reports are © WJEC CBAC Ltd, from their published past papers. Plumi isn’t affiliated with any exam board. Want whole papers? Every WJEC A-Level Physics paper.

Rather write your answers by hand on iPad? Plumi marks them against the same mark schemes.