# Explain why a gas fills the entire container it is placed in, whilst a solid keeps its own shape regardless of the container it is placed in.

> OCR GCSE Chemistry A: Gateway Science (J248) — C1.1 The particle model · Explain · 4 marks

> A scientist transfers a fixed amount of a substance, first as a solid block and then as a gas, into differently shaped containers.

## Mark scheme (4 marks)

1. In a gas, particles move randomly in all directions
2. Gas particles are relatively spread out / far apart, so they fill all available space
3. In a solid, particles are held in a regular arrangement
4. Solid particles can only vibrate about fixed positions / cannot move past each other, so the overall shape is maintained

## Key terms

- [gas](https://www.gradenine.co.uk/glossary/gas)
- [solid](https://www.gradenine.co.uk/glossary/solid)

## Related

- [Revision notes for OCR GCSE Chemistry A: Gateway Science (J248)](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/explain-why-a-gas-fills-the-f2a36ce9) · Published by Druglandscape Ltd.