# Compare nuclear fission and nuclear fusion in terms of the nuclei involved and the conditions required for each process to occur.

> Eduqas GCSE Physics — 9.4 Nuclear fission and fusion · Compare · 4 marks

## Mark scheme (4 marks)

1. Fission involves a large/heavy nucleus splitting into two smaller nuclei (fragments), whereas fusion involves two small/light nuclei joining together.
2. Fission requires a neutron to be absorbed by the heavy nucleus (to trigger the split).
3. Fusion requires extremely high temperatures (and/or pressures) to occur.
4. High temperatures are needed for fusion because the nuclei must overcome the electrostatic/repulsive force between them (so they can get close enough to fuse).

## Key terms

- [nuclear fission](https://www.gradenine.co.uk/glossary/nuclear-fission)
- [nuclear fusion](https://www.gradenine.co.uk/glossary/nuclear-fusion)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Compare" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/compare-nuclear-fission-and-nuclear-fusion-39bd16fe) · Published by Druglandscape Ltd.