Radioactive decay: past paper questions
Real questions on radioactive decay
The newest 20 of 45 written questions. Open one to see it on the real paper.
- 0625/32 · May/June 2026 · Q9c[2]
The isotope radium-223 is radioactive and has a half-life of 11 days. Calculate the fraction of a sample of radium-223 that remains after 33 days. fraction remaining =
See it on the paper → - 0625/41 · May/June 2026 · Q10b[3]
Complete the following sentences: In a nuclear reactor, a slow‑moving hits a uranium nucleus. This causes the uranium nucleus to split into smaller . This reaction is called nuclear . The reaction releases a large amount of energy. This energy heats to drive a turbine which turns a
See it on the paper → - 0625/42 · May/June 2026 · Q9a(ii)[3]
When a tree dies, no new carbon-14 is absorbed by the tree. A tree contains 16 μg of carbon-14 when it dies. Carbon-14 has a half-life of 5700 years. On Figure 9.1, sketch a graph to show how the mass of carbon-14 in the tree decreases during the first 15 000 years after the tree dies. Show your working and label the a...
See it on the paper → - 0625/42 · May/June 2026 · Q10a(i)[3]
Describe the process which occurs when heavy nuclei undergo fission in a power station.
See it on the paper → - 0625/42 · May/June 2026 · Q10a(ii)[2]
Complete the sentences to describe how energy is used to generate electricity in a nuclear power station. Thermal energy is used to heat to produce at high pressure. This drives a
See it on the paper → - 0625/42 · May/June 2026 · Q10a(iii)[2]
State one advantage and one disadvantage of the use of nuclear energy to generate electricity compared with the use of light from the Sun (solar cells). advantage disadvantage
See it on the paper → - 0625/43 · October/November 2025 · Q8c[2]
Curium‑242 is a radioactive isotope. It emits alpha particles. It has a half‑life of 160 days. After 480 days, the mass of curium‑242 in a sample is 2.4 × 10 –3 g. Calculate the initial mass of curium‑242 in the sample. initial mass of curium‑242 =
See it on the paper → - 0625/41 · May/June 2025 · Q9a(ii)[2]
Complete the nuclide equation for the decay of strontium-90 to yttrium. 90 38 Sr Y + β
See it on the paper → - 0625/41 · May/June 2025 · Q9b(i)[3]
Use Fig. 9.1 to determine the half-life of yttrium. Show your working. half-life = h
See it on the paper → - 0625/41 · May/June 2025 · Q9b(ii)[1]
Explain the difference between the count rate in Table 9.1 and the count rate due to yttrium plotted on the graph in Fig. 9.1.
See it on the paper → - 0625/42 · May/June 2025 · Q9b(i)[2]
Complete the nuclide equation for this decay. 223 88 Ra Rn + α (i)
See it on the paper → - 0625/42 · May/June 2025 · Q9c(i)[1]
Explain why a source of gamma radiation is used.
See it on the paper → - 0625/43 · May/June 2025 · Q11b(i)[3]
Complete the nuclear equation for the decay. 23 4 Pa 9 1
See it on the paper → - 0625/32 · February/March 2025 · Q11c[2]
Compare the penetrating abilities of alpha particles, beta particles and gamma rays.
See it on the paper → - 0625/33 · October/November 2024 · Q10c[2]
Table 10.1 time / s count rate counts / s 0 300 22 200 44 150 66 100 88 75 Use the information in Table 10.1 to determine the half-life of the radioactive sample. half-life = s (c) A teacher provides the data in Table 10.1 about the decay of a radioactive sample.
See it on the paper → - 0625/43 · October/November 2024 · Q8a(ii)[3]
A nucleus of boron (B) contains 5 protons and 5 neutrons. Complete the nuclide equation for this fission reaction. B + 10 n Li + α
See it on the paper → - 0625/33 · May/June 2024 · Q10c(ii)[3]
The teacher obtains data for a decay curve. Fig. 10.1 shows the decay curve for the sample of protactinium‑234m. 1000 count rate count / s 900 800 700 600 500 400 300 200 100 0 0 50 100 150 200 250 300 350 time / s Fig. 10.1 Calculate the half‑life of protactinium‑234m using the information in Fig. 10.1. Clearly show y...
See it on the paper → - 0625/42 · May/June 2024 · Q9a(ii)[2]
Give two reasons why alpha‑emitters are not used as radioactive tracers inside the body.
See it on the paper → - 0625/32 · February/March 2024 · Q10c[2]
An isotope of carbon has a half-life of 5700 years. A sample contains 120 mg of this isotope. Calculate the time taken for this isotope of carbon to decay from 120 mg to 15 mg. time taken = years
See it on the paper → - 0625/42 · February/March 2024 · Q9a(ii)[4]
Some of the alpha particles are deflected through angles less than 90° and a few are deflected through 180°. State and explain two conclusions about the nuclei of atoms from this observation. conclusion explanation conclusion explanation
See it on the paper →
What examiners said
There were many fully correct nuclide equations. Where partial credit was gained, it was usually for correctly inserting the proton number and the nucleon number for the beta particle. Some weaker candidates gave yttrium the same atomic number as strontium.
— Examiner report, May/June 2025, 0625/41 Q9(a)(ii) (Cambridge)
Many candidates gained full credit here, demonstrating confidence in using a decay curve to find the half-life of yttrium. Misreading the time axis led to some candidates gaining only partial credit for otherwise correct methods. Weaker candidates often halved the time rather than the count rate. A few candidates tried to correct the graph for background radiation, not realising that this had alre...
— Examiner report, May/June 2025, 0625/41 Q9(b)(i) (Cambridge)
Stronger candidates realised that the difference between the table and the graph was the presence or absence of background radiation count rate. Weaker candidates often answered by repeating information provided in the question rather than explaining the difference.
— Examiner report, May/June 2025, 0625/41 Q9(b)(ii) (Cambridge)
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