# A nuclear power station produces radioactive waste. A safety officer states that one sample of waste has an activity of 5 000 000 Bq. State what is meant by the term 'activity' and explain what the unit becquerel (Bq) tells us about this sample.

> Pearson Edexcel International GCSE Physics (4PH1) — 7.1 Units · State · 4 marks

> Radioactive waste from nuclear reactors must be disposed of carefully, usually by burying it in sealed drums deep underground. The activity of a radioactive source decreases over a period of time.

## Mark scheme (4 marks)

1. Activity is the rate at which unstable nuclei decay (accept: number of decays per unit time)
2. One becquerel equals one decay per second (accept: 1 Bq = 1 decay per second)
3. The sample undergoes 5 000 000 decays every second (accept: 5 000 000 nuclei decay per second)
4. The activity of the sample will decrease over time (as the number of unstable nuclei in the sample decreases)

## Key terms

- [activity](https://www.gradenine.co.uk/glossary/activity)
- [becquerel](https://www.gradenine.co.uk/glossary/becquerel)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "State" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-nuclear-power-station-produces-radioactive-aafdd609) · Published by Druglandscape Ltd.