Fission is a process in which the nucleus splits into two parts that are roughly the same size of the original nucleus. In fusion, two nuclei fuse, or combine, to form one nucleus. These reactions seem to be opposite to each other and yet both release large amounts of energy. Explain why this is not a contradiction.
The fission and fusion both works on the principle of mass energy equivalence. According to this the mass and energy are equivalent. Mass and energy may be converted in to each other ...
This explains how energy is liberated in both fusion and fission.