Does Fusion absorb energy?

Hint: In order to solve this question, we should know that nuclear processes are those where nuclei of atoms either collide or split into other larger or smaller nuclei and thus produce energy which is called nuclear energy, here we will discuss nuclear fusion.

Complete answer:
There are mainly two types of nuclear process Nuclear fission and Nuclear Fusion, Nuclear fission is those where unstable heavy atomic nuclei split into smaller nuclei and due to a reduction in mass of the product with respect to parental nuclei, a large amount of energy is released so Nuclear Fission always release energy.

Nuclear Fusion is the process when two or more light nuclei collide with each other and form a heavy nucleus thus due to the difference between the mass of the reactants and product, a large amount of energy is released or absorbed depending upon the atomic nucleus. In nuclear Fusion reactions when the nucleus is lighter than iron participates then there is always a release of a large amount of energy whereas when the nucleus heavier than iron takes part in the reaction, there is the absorption of energy that takes place to the product nucleus.

Hence, the Nuclear Fusion reactions release energy for the nucleus lighter than iron and absorb energy from the nucleus heavier than iron.

Note: It should be remembered that a large amount of energy is released during nuclear reactions due to the mass-energy relation such that even a very small amount of mass can produce a large amount of energy and this energy is given by the relation between energy E, mass m and velocity of light c as $E = m{c^2}.$