# Use the kinetic theory of matter to explain what happens to the particles in a gas when the gas is compressed into a smaller volume at constant temperature.

> WJEC GCSE Physics (Wales) — 1.8 Kinetic theory · Explain · 4 marks

## Mark scheme (4 marks)

1. The gas particles are closer together / the space between particles decreases
2. The particles collide with the walls more frequently / more collisions per second with the walls
3. Because temperature is constant, the average speed / kinetic energy of the particles remains the same
4. Therefore the pressure of the gas increases

## Key terms

- [kinetic theory](https://www.gradenine.co.uk/glossary/kinetic-theory)
- [temperature](https://www.gradenine.co.uk/glossary/temperature)
- [particles](https://www.gradenine.co.uk/glossary/particles)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" 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/use-the-kinetic-theory-of-matter-ca6801ec) · Published by Druglandscape Ltd.