What happens in nuclear fission reactions?

A. release neutrons as a by-product

B. occur gradually

C. release alpha particles as a by-product

D. occur spontaneously

A. release neutrons as a by-product

Explanation:

Nuclear fission: In nuclear fission, an unstable atom splits into two or more smaller pieces that are more stable, and releases energy in the process. The fission process also releases extra neutrons, which can then split additional atoms, resulting in a chain reaction that releases a lot of energy.