11 Carbon-12 is a stable isotope of carbon. Its nuclide notation is shown in Fig. 11.1. Carbon-14 is an unstable isotope of carbon. Its nuclide notation is shown in Fig. 11.2. 1 6 2C 1 6 4C Fig. 11.1 Fig. 11.2 (a) Determine the numbers of electrons, protons and neutrons in an atom of carbon-12 and the numbers of electrons, protons and neutrons in an atom of carbon-14. Complete Table 11.1. Table 11.1 carbon-12 carbon-14 number of electrons number of protons number of neutrons [3] (b) Fig. 11.3 shows the decay curve for a sample of carbon-14. 0 2 000 5000 10 000 time / years 15 000 20 000 25 000 0 4 000 6 000 8 000 10 000 12 000 14 000 count rate counts / s 16 000 18 000 Fig. 11.3 Use the graph to determine the half-life of carbon-14. half-life = … years [2] [Total: 5]

11(a) carbon-12 carbon-14 number of electrons 6 6 B1 number of protons 6 6 B1 number of neutrons 6 8 B1 3 11(b) any indication on graph of line from 8000 C1 5600 (years) A1

11 (a) The nuclide notation A ZX describes the nucleus of an atom. Draw a line from each symbol to the correct description of the symbol. symbol description half-life value A neutron number nucleon number Z type of radiation proton number [2] (b) The activity of a sample of a radioactive nuclide is measured in June of each year. In June 2004 the activity was 80 000 counts / s. In June 2014 the activity was 20 000 counts / s. (i) Show that the half-life of the nuclide is 5 years. [3] (ii) Determine the year when the activity of the sample was 10 000 counts / s. year = … [2] [Total: 7]

11(a) line from A to middle box: nucleon number B1 line from Z to bottom box: proton number B1 11(b)(i) (from June 2004 to June 2014 =) 10 (years) B1 (decrease in activity from) 80 000 (Bq) to 20 000 (Bq) takes 2 half-lives B1 10 ÷ 2 = (5 years) B1 11(b)(ii) (decrease in activity from) 20 000 (Bq) to 10 000 (Bq) is one half-life C1 so half the time difference = 5 years OR 2019 A1 (a) To earn the first mark, you must draw a line connecting 'A' to 'nucleon number'. To earn the second mark, you must draw a line connecting 'Z' to 'proton number'. (b)(i) To earn the first mark, you must correctly identify the time elapsed as 10 years. To earn the second mark, you must recognize that the activity decreasing from 80 000 Bq to 20 000 Bq represents two half-lives. To earn the third mark, you must divide the total time by the number of half-lives (10 ÷ 2) to show the half-life is 5 years. (b)(ii) To earn the first mark, you must recognize that the activity decreasing from 20 000 Bq to 10 000 Bq represents one half-life. To earn the second mark, you must add one half-life (5 years) to the year 2014 to get the final answer of 2019.

11 (a) A nucleus of nitrogen-13 has the nuclide notation: 13 7N. Determine: (i) the number of protons in one nucleus of nitrogen-13 … [1] (ii) the number of neutrons in one nucleus of nitrogen-13 … [1] (iii) the number of electrons in one neutral atom of nitrogen-13. … [1] (b) Fig. 11.1 shows a counter measuring the radioactivity of a sample of nitrogen-13. sample of nitrogen-13 counter Fig. 11.1 The counter shows the count rate in counts per minute. Table 11.1 shows the count rate every 5 minutes. Table 11.1 time / min count rate due to nitrogen-13 counts / min 0 300 5 212 10 150 15 106 20 75 25 53 Calculate the half-life of nitrogen-13 using information from Table 11.1. half-life of nitrogen-13 = … min [2] [Total: 5]

11(a)(i) 7 B1 11(a)(ii) 6 B1 11(a)(iii) 7 B1 11(b) using a pair of values e.g. 300 and 150 OR 212 and 106 etc. C1 (difference in time is) 10 (min) A1

11 (a) α (alpha)‑particles, β (beta)‑particles and γ (gamma)‑rays have different characteristics. Complete Table 11.1 by indicating the correct type of radiation for each characteristic. The first one is done for you. Table 11.1 characteristic type of radiation α‑particles (alpha‑particles) β‑particles (beta‑particles) γ‑rays (gamma‑rays) largest mass ✓ most ionising most penetrating negatively charged greatest speed [3] (b) A sample of radioactive material contains 80 mg of sodium‑24. The half‑life of sodium‑24 is 15 hours. Calculate the mass of sodium‑24 remaining in the sample after 45 hours. mass remaining = …mg [3] [Total: 6]

11(a) property type of radiation α-particles β-particles γ-rays largest mass   most ionising   most penetrating   negatively charged   greatest speed  B3 11(b) idea of 3 half-lives OR 45 ÷ 15 C1 80 ÷ 8 OR 80 × ½ × ½ × ½ C1 10 (mg) A1 (a) To earn these marks, you must correctly identify alpha particles as most ionising, gamma rays as most penetrating, beta particles as negatively charged, and gamma rays as having the greatest speed. (b) To earn these marks, you must show the idea of 3 half-lives (e.g., 45 ÷ 15), correctly calculate the remaining mass by dividing the initial mass by 8 (or multiplying by 1/2 three times), and state the final answer of 10 mg.

Cambridge IGCSE Physics · 0625

IGCSE Physics (0625) Nuclear physics past paper questions

Nuclear-physics questions cover the nuclear atom, isotopes, radioactive decay, and half-life.

434 free questions from 2016–2025, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Nuclear physics in IGCSE Physics 0625 exams, 2020–2025

Across 2020–2025, Nuclear physics accounted for 447 questions worth 986 marks in Cambridge IGCSE Physics (0625) papers.

By year
Year	Questions	Marks
2020	70	152
2021	76	172
2022	66	160
2023	73	164
2024	83	170
2025	79	168

Most-tested subtopics

5.2 Radioactivity575 marks
5.1 The nuclear model of the atom466 marks

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Paper 1 · 176 qs
Paper 2 · 185 qs
Paper 3 · 41 qs
Paper 4 · 45 qs

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2021 Feb/Mar · Paper 3 · Q11 · 5 marks
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2021 May/Jun · Paper 3 · Q11 · 7 marks
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2021 May/Jun · Paper 3 · Q11 · 5 marks
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2021 Oct/Nov · Paper 3 · Q11 · 6 marks
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2025 May/Jun · Paper 2 · Q37 · 1 mark
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Mark scheme — 2025 Paper 2 Q37
Answer: C
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