plumiRadioactive decay and half-life: Edexcel A‑Level Physics questions
Every Edexcel A-Level Physics exam question on Radioactive decay and half-life (specification points 168–173), 2016–2025, with its mark scheme and examiner’s report.
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Q18(a)
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Q18(b)(i)
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Q18(b)(ii)
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Q4(a)(i)
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Q4(a)(ii)
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Q4(b)
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Q19(a)(i)
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Q19(a)(ii)
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Q19(b)
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Q19(c)(i)
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Q19(c)(ii)
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Q7(a)
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Q7(b)
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Q7(c)(i)
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Q7(c)(ii)
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All 62 questions on Radioactive decay and half-life, as a list
- June 2025, Paper 2, Q8 (1 mark): Some rocks contain polonium. The polonium is radioactive, and decays to a stable isotope of lead. Which of the following graphs shows how the number N of lead a
- June 2025, Paper 2, Q18(a) (2 marks): Complete the following nuclear equation to represent the decay of caesium. (2) 0ν– 137 – + 0 55Cs → .....Ba + .....β ..... ..... ..... ..... e ..... .....
- June 2025, Paper 2, Q18(b)(i) (3 marks): The activity of 137Cs in 1 kg of sediment. Calculate the number of atoms of (3) 137Cs = Number of atoms of
- June 2025, Paper 2, Q18(b)(ii) (2 marks): Calculate the time taken for 10% of the 137Cs atoms to have decayed. (2) Time taken =
- June 2025, Paper 3, Q4(a)(i) (3 marks): Student A set up the apparatus as shown. source GM tube counter d Student B used the same distance d but rotated the GM tube by 90°, as shown below. source GM t
- June 2025, Paper 3, Q4(a)(ii) (4 marks): Explain two modifications to the experimental method which would improve the accuracy of the data. (4)
- June 2025, Paper 3, Q4(b) (2 marks): Student A suggests that the investigation into the inverse square law for a gamma radiation source could be carried out successfully using a radium‑226 source.
- June 2024, Paper 2, Q3 (1 mark): The isotope 221 87Fr undergoes a series of alpha and beta decays before forming 205 81Tl. Which row of the table shows the number of alpha and beta particles em
- June 2024, Paper 2, Q19(a)(i) (2 marks): State what is meant by spontaneous and random in this context. (2)
- June 2024, Paper 2, Q19(a)(ii) (2 marks): Explain why the decay constant of an isotope can be determined even though nuclear decay is random. (2)
- June 2024, Paper 2, Q19(b) (4 marks): A radioactive source used in a school laboratory emits alpha and beta radiation. Describe how the percentage of the activity due to beta radiation may be determ
- June 2024, Paper 2, Q19(c)(i) (3 marks): Determine the percentage of the initial activity that would be expected today for the americium‑241 source. half-life of americium-241 = 432 years (3) Expected
- June 2024, Paper 2, Q19(c)(ii) (3 marks): The decay products of americium are unstable and undergo a series of further decays. The table shows the first three decays in this sequence. Isotope Decay prod
- June 2024, Paper 3, Q7(a) (2 marks): Complete the nuclear equation for the decay of radon. (2) 220 .....α 86Rn → ..... .....Po + ..... ..... ..... ..... ..... ..... ..... ..... .....
- June 2024, Paper 3, Q7(b) (2 marks): Radon is produced in the ground and escapes into the atmosphere. Explain why this is a safety hazard. (2)
- June 2024, Paper 3, Q7(c)(i) (2 marks): Explain why a current is produced in the decay chamber. (2)
- June 2024, Paper 3, Q7(c)(ii) (3 marks): A teacher is demonstrating the operation of the decay chamber to her class. She squeezes the bottle to introduce radon into the chamber. She claims that within
- June 2023, Paper 2, Q7 (1 mark): Carbon‑14 is a radioactive isotope with a decay constant of 1.2 × 10 –4 year –1. The fossil of a plant contains 24% of the amount of carbon‑14 that would have b
- June 2023, Paper 2, Q10 (1 mark): A radioactivity monitoring badge is worn by people who might be exposed to radiation. The badge is made from photographic film wrapped in thin paper and then he
- June 2022, Paper 2, Q10 (1 mark): A student used a Geiger-Müller (GM) tube to determine a value for the background count. He recorded the count for 2 minutes, every 15 minutes, as shown in the t
- June 2022, Paper 2, Q13 (4 marks): Actinium-225 and bismuth-210 are radioactive isotopes. A sample of each isotope is prepared so that each sample has the same number of nuclei initially. Explain
- June 2022, Paper 2, Q21(a) (2 marks): Rubidium decays to strontium via β− decay. Complete the nuclear equation representing the decay. β− + ν– Rb → 87 Sr + 37 e (2)
- June 2022, Paper 2, Q21(b) (5 marks): A sample of Moon rock from the Apollo 11 mission was analysed to determine the age of the rock. When the sample was analysed the number of rubidium atoms was NR
- June 2022, Paper 2, Q21(c) (1 mark): Give a reason why the half-life of the rubidium isotope is hard to determine. (1)
- June 2022, Paper 2, Q21(d) (2 marks): Recent investigations suggest that the half-life of the rubidium isotope may be larger than the traditionally accepted value. Explain how this would affect the
- June 2022, Paper 3, Q8(a) (2 marks): Deduce whether alpha radiation or beta radiation from the inside of the bottle is detected by the GM tube. (2)
- June 2022, Paper 3, Q8(b)(i) (4 marks): Determine the half-life of the protactinium. (4) Half-life of protactinium =
- June 2022, Paper 3, Q8(b)(ii) (2 marks): Explain why the count rate doesn’t reach zero. (2)
- June 2022, Paper 3, Q12(a)(i) (2 marks): Complete the nuclear equation for the decay of caesium-137. 55Cs → Ba + β− + 0 0νe 137 (2)
- June 2022, Paper 3, Q12(a)(ii) (4 marks): An activity of 2.35 × 1012 Bq per m3 of water in the reservoir was measured. It is suggested that a safe level for the activity of all water in the reservoir wo
- June 2022, Paper 3, Q12(b) (6 marks): The most common radionuclide amongst the fission products in the fuel was iodine-131, which decays with a half-life of 8.0 days to form a stable isotope of the
- November 2021, Paper 2, Q20(a)(i) (2 marks): Show that the decay constant for uranium is about 5 × 10−18 s−1 half-life of uranium = 1.41 × 1017 s (2)
- November 2021, Paper 2, Q20(a)(ii) (6 marks): Calculate the percentage of uranium, by mass, in the glass. area of GM tube window = 6.36 × 10−5 m2 surface area of vase = 0.0177 m2 background count rate = 525
- November 2021, Paper 2, Q20(a)(iii) (2 marks): The uranium decays by emitting alpha particles. Criticise the method used to determine the percentage of uranium in the vase. (2)
- November 2021, Paper 3, Q2(a) (3 marks): Criticise the student’s method for determining the count at this position. (3)
- November 2021, Paper 3, Q2(b) (5 marks): From his results the student determined that the activity of the source was 3.0 Bq. Comment on his value for the activity of the source. (5)
- November 2021, Paper 3, Q4(a) (1 mark): State what is meant by spontaneous decay. (1)
- November 2021, Paper 3, Q4(b) (6 marks): Explain why there is an exponential decrease in the rate of decay for a sample containing a large number of unstable nuclei. (6)
- October 2020, Paper 2, Q10 (1 mark): A detector is placed 30 cm from a gamma source, the count rate is 64 counts per minute. The detector is then placed 60 cm from the source. The background rate i
- October 2020, Paper 2, Q16(a)(i) (2 marks): The uranium isotope 238 92U becomes the lead isotope 206 82Pb through a series of radioactive decays. Calculate the number of α particles and the number of β pa
- October 2020, Paper 2, Q16(a)(ii) (3 marks): The half-life of 238 92U is 4.47 × 109 years. The half-lives of the other stages in the decay to 206 82Pb are relatively so short that they can be ignored. Ther
- October 2020, Paper 3, Q4 (6 marks): *4 Radium is a radioactive element. The most common isotope of radium has a half-life of almost two thousand years. A sample of radium can remain at a higher te
- June 2019, Paper 2, Q4 (1 mark): The radium isotope "ggRa is unstable and undergoes a series of a and f emissions until a stable isotope of lead 202Pb is formed. Which of the following nuclear
- June 2019, Paper 2, Q18(a) (2 marks): Give reasons why the sealed plastic bag is suitable for collecting the gas. (2)
- June 2019, Paper 2, Q18(b)(i) (4 marks): Show that the activity of the thorium-230 in the mantle is about 4.0 x 10° Bq. 230 g of thorium-230 contains 6.02 x 1023 atoms half-life of thorium-230 = 75400
- June 2019, Paper 2, Q18(b)(ii) (4 marks): Determine the volume of helium gas that could be collected in a year as a result of alpha emission. Assume that the temperature is 22.0°C and the pressure is 1.
- June 2018, Paper 2, Q5 (1 mark): Select the row of the table that describes the relative ionisation and relative penetration of nuclear radiations. Most ionising Most penetrating A Į Į B Į Ȗ C
- June 2018, Paper 2, Q7 (1 mark): A nucleus of protactinium, 91 231PaGHFD\VE\HPLWWLQJDQĮSDUWLFOH The nucleus formed is A 233Am 95 B 235 Np 93 C 227Ac 89 D 229Fr 87
- June 2018, Paper 2, Q18(a)(i) (3 marks): In a sample of 1.0 g of phosphogypsum, the activity of radium-226 is 1.3 Bq. Calculate the number of nuclei of radium-226 in this sample. (3) Number of nuclei =
- June 2018, Paper 2, Q18(a)(ii) (3 marks): Calculate the time in years it would take before this sample reached the permitted level of decay rate. (3) Time = years
- June 2017, Paper 2, Q19(a) (2 marks): Potassium‑40 undergoes β– decay, producing a stable isotope of calcium. Complete the nuclear equation for this decay. (2) 19K → ....Ca + ....β 40 .... .... ....
- June 2017, Paper 2, Q19(b)(i) (2 marks): The potassium chloride sample has a mass of 300 mg. Show that the number of nuclei of potassium‑40 in the sample is about 3 × 1017. number of potassium nuclei i
- June 2017, Paper 2, Q19(b)(ii) (3 marks): Show that the activity of this sample is about 5 Bq. half‑life of potassium‑40 = 1.25 × 109 years (3)
- June 2017, Paper 2, Q19(b)(iii) (3 marks): With no sample in front of the Geiger‑Müller tube, a count rate of 15 counts per minute is recorded. When the potassium chloride test sample is placed next to t
- June 2017, Paper 2, Q19(b)(iv) (2 marks): Explain a possible reason why only a low proportion of the decays are detected. (2)
- June 2017, Paper 2, Q19(c) (1 mark): The science department also has a sample of strontium‑90. This undergoes beta decay with a half‑life of 29 years. State why the half‑life of potassium-40 makes
- June 2017, Paper 3, Q10(a) (2 marks): Describe how to determine the corrected count rate from the source. (2)
- June 2017, Paper 3, Q10(b)(i) (2 marks): Explain why this arrangement could lead to more accurate data. (2)
- June 2017, Paper 3, Q10(b)(ii) (2 marks): Explain another modification to the experimental method which would improve the accuracy of the data. (2)
- June 2017, Paper 3, Q10(c)(i) (1 mark): Draw a line of best fit on the graph. (1)
- June 2017, Paper 3, Q10(c)(ii) (4 marks): The student concluded that the graph was consistent with the gamma radiation intensity obeying an inverse square law. Discuss the extent to which the data obtai
- June 2017, Paper 3, Q10(d) (2 marks): It is suggested that the investigation into the way in which gamma radiation spreads out from a source, using the apparatus as shown in (b), could be carried ou
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