Draw a plot of BE/A versus mass numbers

Draw a plot of BE/A versus mass number A for $2\le A\le 170.$ Use this graph to explain the release of energy in the process of nuclear fusion of two light nuclei.
OR
Using the curve for the binding energy per nucleon as a function of mass number A, state clearly how the release in energy in the processes of nuclear fission and nuclear fusion can be explained.

The above curve shows that
(i) when a heavy nucleus breaks into two medium sized nuclei (in nuclear fission), the BE / nucleon increases resulting in the release of energy.
(ii) when two small nuclei combine to form a relatively bigger nucleus in nuclear fusion, BE i nucleon increases,resulting in the release of energy.aa
OR
The constancy of the binding energy in the range 30 < A < 170 is a consequence of the fact that the nuclear force is short-ranged. If a nucleon can have a maximum of p neighbours within the range of nuclear force, its binding energy would be proportional to p. If we increase A by adding nucleons, they will not change the binding energv of a nucleon inside. Since most of the nucleons in a large nucleus reside inside it and not on the surface, the change in binding energy per nucleon would be small. Hence, the binding energy per nucleon is a constant, [saturation property of nuclear force.]