# Describe the life cycle of a star that is similar in size to the Sun, starting from a nebula. Include the names of each stage and the key processes involved.

> Edexcel A-Level Physics (9PH0) — 7.1 Electric fields · Describe · 5 marks

## Mark scheme (5 marks)

1. A nebula (cloud of dust and gas) is pulled together by gravitational attraction to form a protostar
2. The protostar reaches a stable main sequence stage where the outward pressure from fusion balances the inward gravitational force
3. When hydrogen runs out, the star expands to form a red giant, fusing heavier elements
4. Once fusion reactions end, the star contracts and cools to form a white dwarf
5. Correct sequence of all named stages: nebula → protostar → main sequence star → red giant → white dwarf

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-life-cycle-of-a-a8ff94a7) · Published by Druglandscape Ltd.