Answer:
addition of a neutron
Explanation:
Nuclear fission is a radioactive decay process in which a heavy nucleus spontaneously disintegrates into lighter ones accompanied by the release of energy.
An atom whose neutron/proton ratio is the same as that of the stability ratio of that atom is said to be stable. When such an atom is bombarded with a neutron particle, the stability ratio is offset. What results is a radioactive decay of such a nucleus. This form of decay is a nuclear fission.
A series of chain reaction is produced though this until the stability ratio is reached.
