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Physics · 2025 · 2 marks
CBSE 2025 · Region 7 · Set 1 · Q21
Briefly explain how energy is produced in stars, giving two examples of the nuclear reactions involved.
Briefly explain how energy is produced in stars, giving two examples of the nuclear reactions involved.
Marking-scheme solution
Energy is produced in stars due to Nuclear fusion.
Two lighter nuclei fuse to form a heavier nucleus which is more stable, hence energy is released.
Alternatively: Due the difference in masses in reactants and products, mass is converted into energy. Hence energy is released.
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CBSE Class 12 Physics past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.