Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Nucleosynthesis Across Stellar Life Cycles
When stars are formed, they contain mostly hydrogen.
Describe how stars produce all other naturally occurring elements.
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Marking points
- 1 Gives a detailed and accurate account of element production by fusion and supernovae.
- 2 Describes hydrogen nuclei fusing to form helium at high temperature.
- 3 Describes later fusion producing heavier elements up to iron.
- 4 Describes massive-star supernovae creating elements heavier than iron.
Full-mark answer
At the very high temperatures in stars, hydrogen nuclei fuse to form helium nuclei. When hydrogen in the core runs low, helium and then other nuclei can fuse to make progressively heavier elements, up to iron. In massive stars, a supernova produces elements heavier than iron.
Why this answer loses marks
Stars make every element by fusing hydrogen.
This misses later fusion stages, the iron limit, and the supernova route for elements beyond iron.