# Natural gas, coal and petroleum are all fossil fuels. Describe how fossil fuels are formed and explain why they are described as non-renewable.

> Cambridge International IGCSE Chemistry (0620) — 11.3 Fuels · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. Fossil fuels formed from the remains of ancient plants and/or animals (organisms)
2. Over millions of years, buried under layers of rock/sediment, subjected to heat and pressure
3. Fossil fuels take millions of years to form
4. They are being used/burned faster than they can be replaced/reformed, so stocks will eventually run out

## Key terms

- [fossil fuel](https://www.gradenine.co.uk/glossary/fossil-fuel)
- [non-renewable](https://www.gradenine.co.uk/glossary/non-renewable)
- [petroleum](https://www.gradenine.co.uk/glossary/petroleum)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](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/natural-gas-coal-and-petroleum-are-90ea89f5) · Published by Druglandscape Ltd.