Answer:
Neutrons, energy
Step-by-step explanation:
Nuclear fission is a process by which the nucleus of a heavy atom is split into two or more daughter nuclei, releasing neutrons and energy.
Hence, nuclear fission involves the breaking up of a heavy nucleus. This breaking up may be induced by bombarding the heavy nucleus with a small particle such as a neutron. This usually leads to a chain reaction as the nucleus fragments into daughter nuclei releasing more neutrons and tremendous energy in the process.