# 9702 P4 Radioactive decay Topic Questions

> CIE IAL 9702 P4: every Radioactive decay topic question from 6 papers (2025), grouped by syllabus point. 19 questions, 40 marks, with direct links into the…

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CIE IAL · Physics · 9702 P4 · A Level

Every 9702 P4 Radioactive decay topic question from the 2025–2027 syllabus, drawn from 6 papers (2025) 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.

- 9702 P4
- 6 subtopics
- 19 topic questions
- 6 papers
- 40 tagged marks
- [Back to Radioactive decay](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/)
- [All paper codes](https://www.examsci.com/topics/)

Core finding

**6 understand the exponential nature of radioactive decay, and sketch… is the most frequently assessed subtopic in Radioactive decay, with 8 topic questions and 22 marks across 3 papers.** 3 define activity and decay constant, and recall and use … follows with 7 topic questions and 15 marks. The topic contains 6 subtopics, 19 topic questions and 40 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

- [6 understand the exponential nature of radioactive decay, and sketch and use the relationship $x = x_0 e^{-\lambda t}$, where x could represent activity, number of undecayed nuclei or received count rate](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/6-understand-the-exponential-nature-of-radioactive-decay-and-sketch-and-use-the/) (3 papers) — 8 · 33.3%
- [3 define activity and decay constant, and recall and use $A = \lambda N$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/3-define-activity-and-decay-constant-and-recall-and-use-a-lambda-n/) (4 papers) — 7 · 29.2%
- [5 use $\lambda = 0.693 / t_{\frac{1}{2}}$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/5-use-lambda-0-693-t-frac-1-2/) (4 papers) — 4 · 16.7%
- [2 understand that radioactive decay is both spontaneous and random](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/2-understand-that-radioactive-decay-is-both-spontaneous-and-random/) (3 papers) — 3 · 12.5%
- [1 understand that fluctuations in count rate provide evidence for the random nature of radioactive decay](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/1-understand-that-fluctuations-in-count-rate-provide-evidence-for-the-random-nature/) (1 papers) — 1 · 4.2%
- [4 define half-life](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/4-define-half-life/) (1 papers) — 1 · 4.2%

### Marks by subtopic

marks

- [6 understand the exponential nature of radioactive decay, and sketch and use the relationship $x = x_0 e^{-\lambda t}$, where x could represent activity, number of undecayed nuclei or received count rate](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/6-understand-the-exponential-nature-of-radioactive-decay-and-sketch-and-use-the/) (3 papers) — 22 · 40.7%
- [3 define activity and decay constant, and recall and use $A = \lambda N$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/3-define-activity-and-decay-constant-and-recall-and-use-a-lambda-n/) (4 papers) — 15 · 27.8%
- [5 use $\lambda = 0.693 / t_{\frac{1}{2}}$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/5-use-lambda-0-693-t-frac-1-2/) (4 papers) — 7 · 13.0%
- [2 understand that radioactive decay is both spontaneous and random](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/2-understand-that-radioactive-decay-is-both-spontaneous-and-random/) (3 papers) — 5 · 9.3%
- [4 define half-life](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/4-define-half-life/) (1 papers) — 3 · 5.6%
- [1 understand that fluctuations in count rate provide evidence for the random nature of radioactive decay](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/1-understand-that-fluctuations-in-count-rate-provide-evidence-for-the-random-nature/) (1 papers) — 2 · 3.7%

## 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 | |
| --- | --- | --- | --- | --- | --- |
| **[1 understand that fluctuations in count rate provide evidence for the random nature of radioactive decay](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/1-understand-that-fluctuations-in-count-rate-provide-evidence-for-the-random-nature/)** | 1 | 1 | 2 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/1-understand-that-fluctuations-in-count-rate-provide-evidence-for-the-random-nature/) |
| **[2 understand that radioactive decay is both spontaneous and random](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/2-understand-that-radioactive-decay-is-both-spontaneous-and-random/)** | 3 | 3 | 5 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/2-understand-that-radioactive-decay-is-both-spontaneous-and-random/) |
| **[3 define activity and decay constant, and recall and use $A = \lambda N$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/3-define-activity-and-decay-constant-and-recall-and-use-a-lambda-n/)** | 7 | 4 | 15 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/3-define-activity-and-decay-constant-and-recall-and-use-a-lambda-n/) |
| **[4 define half-life](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/4-define-half-life/)** | 1 | 1 | 3 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/4-define-half-life/) |
| **[5 use $\lambda = 0.693 / t_{\frac{1}{2}}$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/5-use-lambda-0-693-t-frac-1-2/)** | 4 | 4 | 7 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/5-use-lambda-0-693-t-frac-1-2/) |
| **[6 understand the exponential nature of radioactive decay, and sketch and use the relationship $x = x_0 e^{-\lambda t}$, where x could represent activity, number of undecayed nuclei or received count rate](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/6-understand-the-exponential-nature-of-radioactive-decay-and-sketch-and-use-the/)** | 8 | 3 | 22 | 2025 | [Open topic questions](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/6-understand-the-exponential-nature-of-radioactive-decay-and-sketch-and-use-the/) |

## Browse every topic question

- [1 understand that fluctuations in count rate provide evidence for the random nature of radioactive decay](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/1-understand-that-fluctuations-in-count-rate-provide-evidence-for-the-random-nature/) — 1 question items · 1 papers — 2 marks · 2025
- [2 understand that radioactive decay is both spontaneous and random](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/2-understand-that-radioactive-decay-is-both-spontaneous-and-random/) — 3 question items · 3 papers — 5 marks · 2025
- [3 define activity and decay constant, and recall and use $A = \lambda N$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/3-define-activity-and-decay-constant-and-recall-and-use-a-lambda-n/) — 7 question items · 4 papers — 15 marks · 2025
- [4 define half-life](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/4-define-half-life/) — 1 question items · 1 papers — 3 marks · 2025
- [5 use $\lambda = 0.693 / t_{\frac{1}{2}}$](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/5-use-lambda-0-693-t-frac-1-2/) — 4 question items · 4 papers — 7 marks · 2025
- [6 understand the exponential nature of radioactive decay, and sketch and use the relationship $x = x_0 e^{-\lambda t}$, where x could represent activity, number of undecayed nuclei or received count rate](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/radioactive-decay/6-understand-the-exponential-nature-of-radioactive-decay-and-sketch-and-use-the/) — 8 question items · 3 papers — 22 marks · 2025

## Other topics in 9702 P4

- [Capacitors and capacitance 17 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/capacitors-and-capacitance/)
- [Centripetal acceleration 25 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/centripetal-acceleration/)
- [Characteristics of alternating currents 21 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/characteristics-of-alternating-currents/)
- [Concept of a magnetic field 3 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/concept-of-a-magnetic-field/)
- [Damped and forced oscillations, resonance 7 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/damped-and-forced-oscillations-resonance/)
- [Discharging a capacitor 16 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/discharging-a-capacitor/)
- [Electric field of a point charge 8 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/electric-field-of-a-point-charge/)
- [Electric fields and field lines 7 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/electric-fields-and-field-lines/)
- [Electric force between point charges 12 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/electric-force-between-point-charges/)
- [Electric potential 26 question items](https://www.examsci.com/topics/cie-ial/physics/9702-paper-4/electric-potential/)

## Topic question rules and edge cases

**How many subtopics does Radioactive decay contain?**

This page lists 6 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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