What happens to the atomic mass of a nucleus during fission?

During nuclear fission, the nucleus of a heavy atom splits into two or more smaller nuclei, along with the release of energy. During this process, the total mass of the resulting products is slightly less than the mass of the original nucleus. This decrease in mass occurs due to the conversion of a small amount of mass into energy, as described by Einstein’s equation (E=mc^2).

When the nucleus breaks apart, the binding energy that holds the nucleus together is released. The energy released is related to this mass difference, which is why the atomic mass of the nucleus decreases slightly in the process. Hence, the correct answer reflects this slight reduction in atomic mass due to the dynamics of mass-energy conversion during fission.