Two nuclei combine to form one nucleus in nuclear fission.

The answer is false.

The two main nuclear processes are nuclear fission and nuclear fusion.

In fission, a large nucleus is bombarded with a high energy neutron, resulting in the breakdown of the nucleus and the release of two smaller nuclei along with neutrons and high amounts of energy.

In nuclear fusion on the other hand, two smaller atomic nuclei possessing high amounts of energy to form a larger nucleus, with the possible release of neutrons. This process is also highly exothermic.