What is radioactivity?: OCR GCSE Physics B questions

Every OCR GCSE Physics B exam question on P5.1 What is radioactivity?, 2018–2025, with its mark scheme and examiner’s report.

All 85 questions on What is radioactivity?, as a list

June 2025, Paper 1 Foundation, Q6(a)(i) (1 mark): Why does the activity of a radioactive source decrease? Tick (✓) one box. Half-life decreases. Half-life increases. The number of undecayed nuclei decreases. Th
June 2025, Paper 1 Foundation, Q6(a)(ii) (1 mark): What will the activity of the radium on the notebook be 2500 years from now? Use the graph. Activity = cps [1]
June 2025, Paper 1 Foundation, Q6(a)(iii) (2 marks): Find the half-life of radium. Use the graph. Half-life = years [2]
June 2025, Paper 1 Foundation, Q6(a)(iv) (2 marks): Explain why the statement below is not correct. The radium on the notebook will be much less radioactive in 100 years’ time. [2]
June 2025, Paper 2 Foundation, Q5(a) (2 marks): An alpha particle is a helium-4 nucleus and can be written as: 4 2He How many protons and neutrons are contained in the nucleus of helium-4? Number of protons =
June 2025, Paper 2 Foundation, Q5(b)(i) (1 mark): What is the activity at 15 seconds? Activity = cpm [1]
June 2025, Paper 2 Foundation, Q5(b)(ii) (1 mark): What is the change in the activity between 15 and 30 seconds? Change in activity = cpm [1]
June 2025, Paper 3 Higher, Q5(a) (3 marks): Find the half-life of radium. Use the graph. Half-life = years [3]
June 2025, Paper 3 Higher, Q5(b)(i) (2 marks): The activity of the radium that remains on the notebook will decrease in the future. Calculate the activity of the radium that remains on the notebook after 3 f
June 2025, Paper 3 Higher, Q5(b)(ii) (1 mark): Calculate the fraction of the number of nuclei that will decay in 3 half-lives. Fraction = [1]
June 2025, Paper 4 Higher, Q3(a) (2 marks): Uranium-235 can be written as: 23 5 2U 9 How many protons and neutrons are contained in the nucleus of uranium-235? Number of protons = Number of neutrons = [2]
June 2025, Paper 4 Higher, Q3(b) (1 mark): Uranium-235 undergoes alpha decay. Which of these is the correct equation for this decay? Tick (✓) one box. 23 5 23 1 2U + 4 2U 0He 9 9 23 5 23 1 2U + 4 2U 1He
June 2025, Paper 4 Higher, Q3(c)(i) (1 mark): What is meant by the half-life of a radioactive isotope? Tick (✓) one box. Half of the decrease in activity per second. The number of atoms formed in half a yea
June 2025, Paper 4 Higher, Q3(c)(ii) (1 mark): Find the activity of the sample at 14 × 108 years. Use the graph. Activity at 14 × 108 years = cpm [1]
June 2025, Paper 4 Higher, Q3(c)(iii) (2 marks): The half-life of uranium-235 is 7 × 108 years. Calculate the activity at 21 × 108 years. Activity at 21 × 108 years = cpm [2]
June 2024, Paper 1 Foundation, Q6(a) (2 marks): Complete the nuclear equation to show the decay of radium‑223 (Ra) to radon (Rn). 223 4 88Ra 2α + Rn [2]
June 2024, Paper 1 Foundation, Q6(b)(i) (1 mark): Which of these is the correct definition of half‑life? Tick (3) one box. The activity after half the age of the sample. The time taken for the activity to reach
June 2024, Paper 1 Foundation, Q6(b)(ii) (1 mark): The graph shows the decay of radium‑223. 500 450 400 350 300 Activity (Bq) 250 200 150 100 50 0 0 2 4 6 8 10 12 14 16 18 20 Time (days) Find the half‑life of ra
June 2024, Paper 2 Foundation, Q3(a) (3 marks): Complete the sentences about the Bohr model of an atom. Put a ring around each correct option. The nucleus has an overall negative / neutral / positive charge.
June 2024, Paper 2 Foundation, Q3(b) (2 marks): Fig. 3.2 shows the Bohr model of two isotopes of the same element. Fig. 3.2 Isotope A Isotope B Neutron – – – – – – Proton Electron Describe the similarities an
June 2024, Paper 2 Foundation, Q3(c) (2 marks): Which two statements describe why the model of the atom has changed over time? Tick (✓) two boxes. Atoms have changed. Experiments have provided new evidence. N
June 2024, Paper 3 Higher, Q10(a) (2 marks): Neutrons are involved in beta decay. Explain why the atomic mass number does not change when a nucleus emits a beta particle. [2]
June 2024, Paper 3 Higher, Q10(b)(i) (2 marks): Complete the equation for beryllium-13 when it decays. 13 + 1 4Be 0n 4 [2]
June 2024, Paper 3 Higher, Q10(b)(ii) (1 mark): The half-life of beryllium-13 is 3 × 10–21 seconds. Describe what is meant by half-life. [1]
June 2024, Paper 3 Higher, Q10(c)(iv) (2 marks): When boron-10 absorbs a neutron, it decays to become stable lithium-7 by emitting alpha and gamma radiation. Show that total mass is conserved in the decay of b
June 2024, Paper 4 Higher, Q3(a) (2 marks): State two reasons why the model of the atom has changed over time. 1 2 [2]
June 2024, Paper 4 Higher, Q3(b) (3 marks): Describe the structure of the nuclear model of the atom. [3]
June 2023, Paper 1 Foundation, Q8(a) (2 marks): Complete the sentences about radioactive substances. Put a ring around each correct option. Atoms in radioactive substances have balanced / stable / unstable nu
June 2023, Paper 1 Foundation, Q8(b) (1 mark): The nuclear equation shows the radioactive decay of a sulfur nucleus to a chlorine nucleus. 35 35 –1e– 0 16S 17Cl + Identify the radioactive decay in the nuclea
June 2023, Paper 1 Foundation, Q8(c) (1 mark): Which statement explains why sulfur and chlorine are different elements? Tick (3) one box. They have different numbers of electrons. They have different numbers
June 2023, Paper 2 Foundation, Q6(a)(i) (1 mark): What is particle X? Put a ring around the correct option. 0e 4 1 2He 0n –1 [1]
June 2023, Paper 2 Foundation, Q6(a)(ii) (2 marks): Complete the sentences about the decay equation. Put a ring around the correct options. 1. When a nucleus of radon-222 decays the mass number reduces by 4 / 2 /
June 2023, Paper 2 Foundation, Q6(b) (1 mark): Half-life is used to measure the length of time of decay. Define the term half-life. [1]
June 2023, Paper 2 Foundation, Q6(c)(i) (1 mark): Ling says that some of the measurements do not lie exactly on the expected decay curve because of experimental errors. Give one other reason why some readings d
June 2023, Paper 3 Higher, Q9(a) (1 mark): What is the typical diameter of an atom? Tick (3) one box. 1 × 103 m 1 × 10–3 m 1 × 10–6 m 1 × 10–10 m [1]
June 2023, Paper 3 Higher, Q9(b) (1 mark): Which example gives the best estimate for the ratio of the relative diameters of the atom and its nucleus? The values in brackets are estimates for the diameter
June 2023, Paper 3 Higher, Q9(c) (1 mark): Ideas about the model of the atom have developed over the last 200 years. Write the numbers 2, 3 and 4 to show the correct historical order. The earliest idea h
June 2023, Paper 3 Higher, Q10(a)(i) (2 marks): Complete the balanced nuclear equation. 35 35 16S Cl + e [2]
June 2023, Paper 3 Higher, Q10(a)(ii) (3 marks): Compare and contrast the composition of the sulfur and chlorine nuclei to explain where the beta particle has come from. [3]
June 2023, Paper 3 Higher, Q10(b)(i) (2 marks): Explain how chlorine nuclei can have differing nuclear masses. [2]
June 2023, Paper 3 Higher, Q10(b)(ii) (2 marks): Calculate the mean nuclear mass. Mean nuclear mass = [2]
June 2023, Paper 4 Higher, Q4(a) (2 marks): Compare the structures of the nuclei of actinium-225 and actinium-227. [2]
June 2023, Paper 4 Higher, Q4(b)(i) (1 mark): State why a nucleus might decay. [1]
June 2023, Paper 4 Higher, Q4(b)(ii) (1 mark): Name the electromagnetic radiation that is emitted in both cases. [1]
June 2023, Paper 4 Higher, Q4(b)(iii) (2 marks): Name one other ionising radiation emitted in each case. Actinium-225: Actinium-227: [2]
June 2022, Paper 1 Foundation, Q2(a)(i) (1 mark): Use a word from the list to complete the sentence. electrons neutrons protons The atom has a positive nucleus surrounded by negative [1]
June 2022, Paper 1 Foundation, Q2(a)(ii) (2 marks): Use words from this list to complete the sentence. charge mass nucleus space volume Almost all of the of the atom is in the [2]
June 2022, Paper 1 Foundation, Q2(b) (1 mark): What is the typical size of an atom? Tick (✓) one box. 1010 m 105 m 10–5 m 10–10 m [1]
June 2022, Paper 1 Foundation, Q2(c)(i) (1 mark): Which statement could be used to describe these atoms? Tick (✓) one box. They are identical They are isotopes They are negative ions They are positive ions [1]
June 2022, Paper 1 Foundation, Q2(c)(ii) (1 mark): One of the atoms is unstable. Which statement can be used to describe this atom? Tick (✓) one box. The neutrons are positively charged. The nucleus may emit a r
June 2022, Paper 2 Foundation, Q8(b) (2 marks): One possible product of the nuclear fission of uranium-235 is strontium-90. Strontium-90 emits beta particles, and decays to yttrium (Yt). Complete the decay eq
June 2022, Paper 2 Foundation, Q8(c)(i) (2 marks): Use the graph to find the half-life of strontium-90. Half-life = years [2]
June 2022, Paper 2 Foundation, Q8(c)(ii) (1 mark): Use the graph to find the percentage activity of strontium-90 after 100 years. Percentage activity = % [1]
June 2022, Paper 2 Foundation, Q8(d)(i) (1 mark): How many protons are there in a strontium-88 nucleus? [1]
June 2022, Paper 2 Foundation, Q8(d)(ii) (1 mark): How many neutrons are there in a strontium-88 nucleus? [1]
November 2021, Paper 1 Foundation, Q11(a) (1 mark): Li comments that there is a problem with Amaya’s experiment. This experiment is not valid. You cannot be confident that the radiation you detect is coming from
November 2020, Paper 1 Foundation, Q13(c) (2 marks): Alpha radiation is also harmful to living organisms. Give two reasons why alpha radiation would not be suitable for disinfecting water. 1 2 [2]
November 2020, Paper 2 Foundation, Q5(a) (1 mark): Complete the two missing values in the table. [1]
November 2020, Paper 2 Foundation, Q5(b) (1 mark): Isotopes of an element are atoms with the same number of protons but a different number of neutrons. Which two atoms are isotopes of the same element? Put a rin
November 2020, Paper 2 Foundation, Q5(c) (1 mark): Carbon-14 is an unstable isotope which decays to nitrogen-14. 1 4C 1 4N + Decay 6 7 particle What is the decay particle emitted when carbon-14 decays? Put a rin
November 2020, Paper 3 Higher, Q3(c) (2 marks): Alpha radiation is also harmful to living organisms. Give two reasons why alpha radiation would not be suitable for disinfecting water. 1 2 [2]
June 2019, Paper 1 Foundation, Q3(a) (1 mark): What is the typical size of an atom? Put a ring around the correct answer. 10–3 m 10–6 m 10–10 m 10–20 m [1]
June 2019, Paper 1 Foundation, Q3(b) (2 marks): Mia finds out about the models of atoms suggested by Dalton and Rutherford. She draws these diagrams. nucleus Dalton model Rutherford model Describe some of the
June 2019, Paper 1 Foundation, Q3(c) (2 marks): Mia finds out more information about the nucleus of the atom on the Internet. Mia ‘The Internet says the nucleus is tiny and negatively charged. It contains pro
June 2019, Paper 1 Foundation, Q3(d)(i) (1 mark): What is the total mass of these two nuclei? Put a ring around the correct answer. 12 – 6 10 + 6 20 + 10 20 + 12 [1]
June 2019, Paper 1 Foundation, Q3(d)(ii) (1 mark): What is the difference between the charges of these two nuclei? Put a ring around the correct answer. 10 – 6 12 – 6 20 – 12 20 – 10 [1]
June 2019, Paper 2 Foundation, Q5(d)(i) (2 marks): Use the graph to determine the half-life of the alpha source. Show your working on the graph. Half-life = years [2]
June 2019, Paper 2 Foundation, Q5(d)(ii) (3 marks): The initial activity of the source is 40 000 counts per second. What is the activity of the source after a time equal to 2 half-lives? Activity = counts per sec
June 2019, Paper 2 Foundation, Q5(d)(iii) (3 marks): On the graph axes above, sketch a graph for another sample of the alpha source that has an initial activity of 30 000 counts per second. [3]
June 2019, Paper 3 Higher, Q5(a) (2 marks): Thorium-232 can be represented as: 232 90Th Complete the correct representation of the isotope of radium shown in Fig. 5.1. Ra [2]
June 2019, Paper 3 Higher, Q5(b) (2 marks): State the type of radiation emitted during the decay shown in Fig. 5.1. Give a reason for your answer. Type of radiation Reason [2]
June 2019, Paper 3 Higher, Q5(c) (1 mark): The isotope of radium is also radioactive. It decays by emitting a beta particle. Add an arrow to the graph in Fig. 5.1 to show this decay. [1]
June 2019, Paper 4 Higher, Q11(b)(i) (3 marks): Sketch a graph to show how the activity of the source changes with time. 2.0 × 107 activity (counts per second) 1.0 × 107 0 0 74 148 time (days) [3]
June 2019, Paper 4 Higher, Q11(b)(ii) (3 marks): The initial activity of another iridium-192 source is different from (b)(i). What fraction of the iridium nuclei are left in the new source after 3 half-lives?
June 2018, Paper 1 Foundation, Q8(a)(i) (1 mark): Which is the number of protons in americium-241? Put a ring around the correct answer. [1] 95 241 241 + 95 241 – 95
June 2018, Paper 1 Foundation, Q8(a)(ii) (1 mark): Which is the number of neutrons in americium-241? Put a ring around the correct answer. [1] 95 241 241 + 95 241 – 95
June 2018, Paper 2 Foundation, Q5(a)(i) (2 marks): Complete the radioactive decay equation for plutonium-238. 238 4 94Pu U + 2 a [2]
June 2018, Paper 3 Higher, Q8(a) (2 marks): Complete these nuclear equations to show the production of technetium-99m. 98 99 42 Mo + n 42 Mo 99 99 42 Mo 43 Tc + e [2]
June 2018, Paper 3 Higher, Q8(c)(i) (2 marks): Calculate the percentage of technetium-99m remaining after 24 hours. Percentage remaining = % [2]
June 2018, Paper 4 Higher, Q3(a)(i) (3 marks): Complete the radioactive decay equation for plutonium-238. 23 8 4Pu U + α 9 [3]
June 2018, Paper 4 Higher, Q3(a)(ii) (3 marks): The plutonium emits 1.6 × 1015 alpha particles every second, each with an energy of 9.0 × 10–13 J. The energy released is all transferred to the internal energy
June 2018, Paper 4 Higher, Q8(a) (2 marks): Use the graph to obtain an estimate of the half-life of americium-241. Show your working on the graph. Half-life = years [2]
June 2018, Paper 4 Higher, Q8(c)(i) (1 mark): What does the number of dice remaining at any roll stand for? [1]
June 2018, Paper 4 Higher, Q8(c)(ii) (1 mark): What does the number of sixes taken out in any roll stand for? [1]
June 2018, Paper 4 Higher, Q8(c)(iii) (3 marks): Explain why the data in this table suggest that the half-life is about 4 ‘rolls’ but that it’s not possible to be exact. [3]

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