Question

what is nuclear fusion​

Answer 1

Nuclear fusion is a reaction in which two or more atomic nuclei are combine to form one or more different nuclei atomic and subatomic particles. The difference in mass between the reactants and products us manifested as either the release or absorption if energy.
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Answer 2

Answer:

$\huge\mathcal{Nuclear\:fusion}$

Nuclear fusion can be defined as a nuclear reaction in which lighter nuclei are combined together to form heavier product nuclie with the release of enormous amount of energy.

Lighter nuclei such as Helium and Lithium when combined together form a heavier nucleus .The mass of the heavier nucleus is less than initial reacting nuclie i.e,that is usually enormious rather than mass.Therefore the law of conservation of energy is satisfied....