# A sealed metal container holds a fixed quantity of gas. The container is placed in a freezer and left until the gas cools to a much lower temperature. Explain what happens to the pressure of the gas inside the container as it cools, using ideas about particles.

> WJEC GCSE Physics (Wales) — 2.3 Forces and motion · Explain · 4 marks

## Mark scheme (4 marks)

1. The temperature of the gas decreases, so the average kinetic energy of the particles decreases.
2. The particles move more slowly / with less speed.
3. The particles collide with the walls of the container with less force.
4. Therefore the pressure of the gas decreases.

## Key terms

- [pressure](https://www.gradenine.co.uk/glossary/pressure)
- [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/a-sealed-metal-container-holds-a-cee8a9c8) · Published by Druglandscape Ltd.