Question

the relationship between matter and energy when a nuclear change occurs?

Answer 1

Nuclear changes occur with a simultaneous release of energy. If we could precisely measure the masses of the reactants and the products of a nuclear reaction, we would notice that the amount of mass drops slightly in the conversion from reactants to products.

Answer 2

I think this is where we could apply the famous equation E=mc2 where E is the energy, m is the mass converted and c is the speed of light. So the amount of energy released is very large compared to the mass converted since the speed of light squared is a very large number.