# State two physical properties of noble gases and explain why noble gases are used in filament light bulbs rather than air.

> Cambridge International IGCSE Chemistry (0620) — 8.5 Noble gases · State / Explain · 4 marks

> Filament light bulbs contain a very hot tungsten wire that glows to produce light. Early bulbs used a vacuum, but modern bulbs are filled with a noble gas.

## Mark scheme (4 marks)

1. Noble gases have low boiling points / exist as gases at room temperature
2. Noble gases have low density / are monatomic
3. Noble gases are chemically unreactive / inert, so they do not react with the hot tungsten filament
4. Air contains oxygen / nitrogen which would react with / oxidise the hot filament, causing it to burn away / break

## Key terms

- [noble gases](https://www.gradenine.co.uk/glossary/noble-gases)
- [filament](https://www.gradenine.co.uk/glossary/filament)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "State / 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/state-two-physical-properties-of-noble-e0f2ea76) · Published by Druglandscape Ltd.