# Crude oil is described as a finite resource. Explain how crude oil was formed and why it is considered a finite resource.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 4.2 Crude oil · Explain · 4 marks

## Mark scheme (4 marks)

1. Crude oil is the remains of an ancient biomass consisting mainly of plankton
2. The plankton/biomass was buried in mud (over millions of years)
3. Crude oil is finite because it takes millions of years to form / it cannot be replaced within a human timescale
4. It is being used/consumed faster than it is being formed / once used up it cannot be replaced

## Key terms

- [finite resource](https://www.gradenine.co.uk/glossary/finite-resource)
- [crude oil](https://www.gradenine.co.uk/glossary/crude-oil)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](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/crude-oil-is-described-as-a-918c6d2f) · Published by Druglandscape Ltd.