Two suitable light nuclei fuse and form a more tightly bound product nucleus while releasing energy. Which change must normally occur for the fusion reaction to be exoergic?
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Question

Two suitable light nuclei fuse and form a more tightly bound product nucleus while releasing energy. Which change must normally occur for the fusion reaction to be exoergic?

G1 Physics · Accepted Answer

For an energy-releasing fusion reaction, the final nucleus is more tightly bound than the initial light nuclei. A useful measure of how tightly nucleons are bound is the binding energy per nucleon. Therefore the products move toward a region of larger binding energy per nucleon. The increase in total binding energy corresponds to a decrease in total rest mass, and the difference appears as released energy. Correct option: B.