# A sealed container holds a fixed quantity of gas at constant temperature. Describe and explain what happens to the pressure of the gas when the volume of the container is reduced.

> WJEC A-Level Physics (Wales) — 2.3 Capacitance (A-Level only) · Describe and explain · 5 marks

## Mark scheme (5 marks)

1. The pressure of the gas increases (when volume is reduced)
2. The gas particles collide with the walls of the container more frequently
3. Because the same number of particles are now in a smaller volume / the particles are closer together
4. Pressure is the perpendicular force per unit area on the walls of the container
5. This is consistent with the pressure-volume relationship: pressure is inversely proportional to volume at constant temperature

## Key terms

- [pressure](https://www.gradenine.co.uk/glossary/pressure)
- [volume](https://www.gradenine.co.uk/glossary/volume)

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-container-holds-a-fixed-62ea2ea0) · Published by Druglandscape Ltd.