# Explain why the smell of a perfume sprayed in one corner of a room can eventually be detected throughout the entire room, whilst the glass bottle containing the perfume keeps its own shape on the shelf.

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

> A person sprays perfume in one corner of a room. After a short time, the smell can be detected across the whole room. The glass bottle the perfume came from remains unchanged on the shelf.

## Mark scheme (4 marks)

1. Perfume particles in the gas (vapour) phase move randomly in all directions
2. Gas particles are relatively spread out / have large gaps between them, allowing them to fill the room
3. The particles in a solid (glass bottle) hold a regular arrangement
4. Solid particles have the least amount of energy and cannot move from their fixed positions, so the solid keeps its shape

## 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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