# WPH15 Nuclear Decay Topic Questions

> Edexcel IAL WPH15: every Nuclear Decay topic question from 20 papers (2020–2026), grouped by syllabus point. 178 questions, 455 marks, with direct links…

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Edexcel IAL · Physics · WPH15 · A Level

Every WPH15 Nuclear Decay topic question from the 2018–current syllabus, drawn from 20 papers (2020–2026) and grouped by syllabus point. Each row opens a page listing the exact question numbers, marks and a direct link into the paper. These are questions by topic, not full papers, so you can revise one topic at a time.

- WPH15
- 10 subtopics
- 178 topic questions
- 20 papers
- 455 tagged marks
- [Back to Nuclear Decay](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/)
- [All paper codes](https://www.examsci.com/topics/)

Core finding

**133 understand the concept of nuclear binding energy and be able to… is the most frequently assessed subtopic in Nuclear Decay, with 38 topic questions and 122 marks across 20 papers.** 142 be able to determine the half-lives of radioactive… follows with 38 topic questions and 119 marks. The topic contains 10 subtopics, 178 topic questions and 455 marks in total. Rows count only the parts tagged to that subtopic, keep the same colour in both charts and repeat paper count, tagged marks and year range in the native table.

## Topic question count and mark distribution

Subtopics are on the vertical axis and sorted from highest to lowest. Only the parts whose knowledge graph matches a subtopic are counted for it, and percentages are each row's share of the tagged total in that chart. A part tagged to several subtopics is counted in each bar, so the bars are not a partition of the topic total.

### Questions by subtopic

question items

- [133 understand the concept of nuclear binding energy and be able to use the equation $\Delta E=c^{2}\Delta m$ in calculations of nuclear mass (including mass deficit) and energy](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/133-understand-the-concept-of-nuclear-binding-energy-and-be-able-to-use-the-equation/) (20 papers) — 38 · 18.2%
- [142 be able to determine the half-lives of radioactive isotopes graphically and be able to use the equations for radioactive decay activity $A=\lambda N$, $\frac{dN}{dt}=-\lambda N$, $N=N_{0}e^{-\lambda t}$ and $A=A_{0}e^{-\lambda t}$ and $\lambda=\frac{\ln 2}{t_{\frac{1}{2}}}$ and derive and use the corresponding log equations.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/142-be-able-to-determine-the-half-lives-of-radioactive-isotopes-graphically-and-be/) (20 papers) — 38 · 18.2%
- [139 be able to write and interpret nuclear equations given the relevant particle symbols](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/139-be-able-to-write-and-interpret-nuclear-equations-given-the-relevant-particle/) (20 papers) — 26 · 12.4%
- [135 understand the processes of nuclear fusion and fission with reference to the binding energy per nucleon curve](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/135-understand-the-processes-of-nuclear-fusion-and-fission-with-reference-to-the/) (15 papers) — 23 · 11.0%
- [138 understand the relationships between the nature, penetration, ionising ability and range in different materials of nuclear radiations (alpha, beta and gamma)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/138-understand-the-relationships-between-the-nature-penetration-ionising-ability-and/) (18 papers) — 23 · 11.0%
- [134 use the atomic mass unit (u) to express small masses and convert between this and SI units](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/134-use-the-atomic-mass-unit-u-to-express-small-masses-and-convert-between-this-and/) (16 papers) — 18 · 8.6%
- [140 CORE PRACTICAL 15: Investigate the absorption of gamma radiation by lead](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/140-core-practical-15-investigate-the-absorption-of-gamma-radiation-by-lead/) (11 papers) — 13 · 6.2%
- [136 understand the mechanism of nuclear fusion and the need for very high densities of matter and very high temperatures to bring about and maintain nuclear fusion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/136-understand-the-mechanism-of-nuclear-fusion-and-the-need-for-very-high-densities/) (11 papers) — 12 · 5.7%
- [137 understand that there is background radiation and how to take appropriate account of it in calculations](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/137-understand-that-there-is-background-radiation-and-how-to-take-appropriate-account/) (10 papers) — 10 · 4.8%
- [141 understand the spontaneous and random nature of nuclear decay](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/141-understand-the-spontaneous-and-random-nature-of-nuclear-decay/) (6 papers) — 8 · 3.8%

### Marks by subtopic

marks

- [133 understand the concept of nuclear binding energy and be able to use the equation $\Delta E=c^{2}\Delta m$ in calculations of nuclear mass (including mass deficit) and energy](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/133-understand-the-concept-of-nuclear-binding-energy-and-be-able-to-use-the-equation/) (20 papers) — 122 · 21.7%
- [142 be able to determine the half-lives of radioactive isotopes graphically and be able to use the equations for radioactive decay activity $A=\lambda N$, $\frac{dN}{dt}=-\lambda N$, $N=N_{0}e^{-\lambda t}$ and $A=A_{0}e^{-\lambda t}$ and $\lambda=\frac{\ln 2}{t_{\frac{1}{2}}}$ and derive and use the corresponding log equations.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/142-be-able-to-determine-the-half-lives-of-radioactive-isotopes-graphically-and-be/) (20 papers) — 119 · 21.2%
- [134 use the atomic mass unit (u) to express small masses and convert between this and SI units](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/134-use-the-atomic-mass-unit-u-to-express-small-masses-and-convert-between-this-and/) (16 papers) — 77 · 13.7%
- [139 be able to write and interpret nuclear equations given the relevant particle symbols](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/139-be-able-to-write-and-interpret-nuclear-equations-given-the-relevant-particle/) (20 papers) — 54 · 9.6%
- [138 understand the relationships between the nature, penetration, ionising ability and range in different materials of nuclear radiations (alpha, beta and gamma)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/138-understand-the-relationships-between-the-nature-penetration-ionising-ability-and/) (18 papers) — 53 · 9.4%
- [135 understand the processes of nuclear fusion and fission with reference to the binding energy per nucleon curve](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/135-understand-the-processes-of-nuclear-fusion-and-fission-with-reference-to-the/) (15 papers) — 42 · 7.5%
- [136 understand the mechanism of nuclear fusion and the need for very high densities of matter and very high temperatures to bring about and maintain nuclear fusion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/136-understand-the-mechanism-of-nuclear-fusion-and-the-need-for-very-high-densities/) (11 papers) — 40 · 7.1%
- [140 CORE PRACTICAL 15: Investigate the absorption of gamma radiation by lead](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/140-core-practical-15-investigate-the-absorption-of-gamma-radiation-by-lead/) (11 papers) — 29 · 5.2%
- [137 understand that there is background radiation and how to take appropriate account of it in calculations](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/137-understand-that-there-is-background-radiation-and-how-to-take-appropriate-account/) (10 papers) — 13 · 2.3%
- [141 understand the spontaneous and random nature of nuclear decay](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/141-understand-the-spontaneous-and-random-nature-of-nuclear-decay/) (6 papers) — 13 · 2.3%

## Subtopic comparison matrix

Curriculum order is by syllabus number, then alphabetically. Every row links to the matching past-paper question list.

| Subtopic | Topic questions | Papers | Marks | Years | |
| --- | --- | --- | --- | --- | --- |
| **[133 understand the concept of nuclear binding energy and be able to use the equation $\Delta E=c^{2}\Delta m$ in calculations of nuclear mass (including mass deficit) and energy](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/133-understand-the-concept-of-nuclear-binding-energy-and-be-able-to-use-the-equation/)** | 38 | 20 | 122 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/133-understand-the-concept-of-nuclear-binding-energy-and-be-able-to-use-the-equation/) |
| **[134 use the atomic mass unit (u) to express small masses and convert between this and SI units](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/134-use-the-atomic-mass-unit-u-to-express-small-masses-and-convert-between-this-and/)** | 18 | 16 | 77 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/134-use-the-atomic-mass-unit-u-to-express-small-masses-and-convert-between-this-and/) |
| **[135 understand the processes of nuclear fusion and fission with reference to the binding energy per nucleon curve](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/135-understand-the-processes-of-nuclear-fusion-and-fission-with-reference-to-the/)** | 23 | 15 | 42 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/135-understand-the-processes-of-nuclear-fusion-and-fission-with-reference-to-the/) |
| **[136 understand the mechanism of nuclear fusion and the need for very high densities of matter and very high temperatures to bring about and maintain nuclear fusion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/136-understand-the-mechanism-of-nuclear-fusion-and-the-need-for-very-high-densities/)** | 12 | 11 | 40 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/136-understand-the-mechanism-of-nuclear-fusion-and-the-need-for-very-high-densities/) |
| **[137 understand that there is background radiation and how to take appropriate account of it in calculations](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/137-understand-that-there-is-background-radiation-and-how-to-take-appropriate-account/)** | 10 | 10 | 13 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/137-understand-that-there-is-background-radiation-and-how-to-take-appropriate-account/) |
| **[138 understand the relationships between the nature, penetration, ionising ability and range in different materials of nuclear radiations (alpha, beta and gamma)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/138-understand-the-relationships-between-the-nature-penetration-ionising-ability-and/)** | 23 | 18 | 53 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/138-understand-the-relationships-between-the-nature-penetration-ionising-ability-and/) |
| **[139 be able to write and interpret nuclear equations given the relevant particle symbols](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/139-be-able-to-write-and-interpret-nuclear-equations-given-the-relevant-particle/)** | 26 | 20 | 54 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/139-be-able-to-write-and-interpret-nuclear-equations-given-the-relevant-particle/) |
| **[140 CORE PRACTICAL 15: Investigate the absorption of gamma radiation by lead](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/140-core-practical-15-investigate-the-absorption-of-gamma-radiation-by-lead/)** | 13 | 11 | 29 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/140-core-practical-15-investigate-the-absorption-of-gamma-radiation-by-lead/) |
| **[141 understand the spontaneous and random nature of nuclear decay](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/141-understand-the-spontaneous-and-random-nature-of-nuclear-decay/)** | 8 | 6 | 13 | 2022–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/141-understand-the-spontaneous-and-random-nature-of-nuclear-decay/) |
| **[142 be able to determine the half-lives of radioactive isotopes graphically and be able to use the equations for radioactive decay activity $A=\lambda N$, $\frac{dN}{dt}=-\lambda N$, $N=N_{0}e^{-\lambda t}$ and $A=A_{0}e^{-\lambda t}$ and $\lambda=\frac{\ln 2}{t_{\frac{1}{2}}}$ and derive and use the corresponding log equations.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/142-be-able-to-determine-the-half-lives-of-radioactive-isotopes-graphically-and-be/)** | 38 | 20 | 119 | 2020–2026 | [Open topic questions](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/142-be-able-to-determine-the-half-lives-of-radioactive-isotopes-graphically-and-be/) |

## Browse every topic question

- [133 understand the concept of nuclear binding energy and be able to use the equation $\Delta E=c^{2}\Delta m$ in calculations of nuclear mass (including mass deficit) and energy](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/133-understand-the-concept-of-nuclear-binding-energy-and-be-able-to-use-the-equation/) — 38 question items · 20 papers — 122 marks · 2020–2026
- [134 use the atomic mass unit (u) to express small masses and convert between this and SI units](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/134-use-the-atomic-mass-unit-u-to-express-small-masses-and-convert-between-this-and/) — 18 question items · 16 papers — 77 marks · 2020–2026
- [135 understand the processes of nuclear fusion and fission with reference to the binding energy per nucleon curve](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/135-understand-the-processes-of-nuclear-fusion-and-fission-with-reference-to-the/) — 23 question items · 15 papers — 42 marks · 2020–2026
- [136 understand the mechanism of nuclear fusion and the need for very high densities of matter and very high temperatures to bring about and maintain nuclear fusion](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/136-understand-the-mechanism-of-nuclear-fusion-and-the-need-for-very-high-densities/) — 12 question items · 11 papers — 40 marks · 2020–2026
- [137 understand that there is background radiation and how to take appropriate account of it in calculations](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/137-understand-that-there-is-background-radiation-and-how-to-take-appropriate-account/) — 10 question items · 10 papers — 13 marks · 2020–2026
- [138 understand the relationships between the nature, penetration, ionising ability and range in different materials of nuclear radiations (alpha, beta and gamma)](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/138-understand-the-relationships-between-the-nature-penetration-ionising-ability-and/) — 23 question items · 18 papers — 53 marks · 2020–2026
- [139 be able to write and interpret nuclear equations given the relevant particle symbols](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/139-be-able-to-write-and-interpret-nuclear-equations-given-the-relevant-particle/) — 26 question items · 20 papers — 54 marks · 2020–2026
- [140 CORE PRACTICAL 15: Investigate the absorption of gamma radiation by lead](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/140-core-practical-15-investigate-the-absorption-of-gamma-radiation-by-lead/) — 13 question items · 11 papers — 29 marks · 2020–2026
- [141 understand the spontaneous and random nature of nuclear decay](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/141-understand-the-spontaneous-and-random-nature-of-nuclear-decay/) — 8 question items · 6 papers — 13 marks · 2022–2026
- [142 be able to determine the half-lives of radioactive isotopes graphically and be able to use the equations for radioactive decay activity $A=\lambda N$, $\frac{dN}{dt}=-\lambda N$, $N=N_{0}e^{-\lambda t}$ and $A=A_{0}e^{-\lambda t}$ and $\lambda=\frac{\ln 2}{t_{\frac{1}{2}}}$ and derive and use the corresponding log equations.](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/nuclear-decay/142-be-able-to-determine-the-half-lives-of-radioactive-isotopes-graphically-and-be/) — 38 question items · 20 papers — 119 marks · 2020–2026

## Other topics in WPH15

- [Astrophysics and Cosmology 303 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/astrophysics-and-cosmology/)
- [Oscillations 145 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/oscillations/)
- [Thermodynamics 111 question items](https://www.examsci.com/topics/edexcel-ial/physics/physics-unit-5-wph15/thermodynamics/)

## Topic question rules and edge cases

**How many subtopics does Nuclear Decay contain?**

This page lists 10 subtopics tagged to the current syllabus. They are ordered by syllabus number, then alphabetically, and each row opens a page of matching past-paper questions.

**How are the subtopic question and mark totals calculated?**

A multiple-choice question contributes one item and its marks to every subtopic it is tagged with. A structured question contributes one item per tagged part, and that part’s marks; untagged parts of the same question are not counted here. A part tagged to several subtopics therefore appears under each of them.

**Why do some subtopics have no numbered prefix?**

Practical-skills statements and some syllabus bullets are unnumbered. Numbered statements come first; unnumbered statements and ties are sorted alphabetically.

**Is the LaTeX rendered without JavaScript?**

Yes. Subtopics that contain formulas are converted to static KaTeX HTML during the build, and the KaTeX stylesheet is served from the same site.

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