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Q.
The main source of sun's energy is:
AFMCAFMC 2003
Solution:
When two lighter nuclei moving at very high speeds fuse together to from a single heavier nucleus, then this phenomenon is called nuclear fusion. The source of huge solar energy is the fusion of lighter nuclei. About $90 \%$ of the solar mass is composed of hydrogen and helium and the rest $10 \%$ contains other elements, most of which are light elements.
The estimated temperature of the interior of the sun is about $2 \times 10^{7} K$. At such a high temperature the atoms of all elements present in the sun are completely ionised to form a hot plasma. Fusion of hydrogen nuclei into helium nuclei is continuously taking place in this plasma, with the continuous liberation of energy.