draw a plot showing the variation of binding energy per nucleon with mass number A. what are the two important conclusions tht can be drawn from this plot??explain with the help of this plot , the release in the processes of nuclear fusion and fission????

Binding energy per  nucleon is practically constant for mass number. (30 <  A  < 170)

Binding energy per nucleon is lower for both light nuclei ( A  < 30) and heavy nuclei ( A > 170). 
 

Importance of Binding energy curve

As we move from heavy nuclei region to the middle region of the plot , there is a gain in the overall binding energy and hence, in the release of energy. This indicates that energy can be released when a heavy nucleus breaks into roughly two equal fragments. This process is called nuclear fission.

When we move from lighter nuclei to heavier nuclei, there will be gain in the overall binding energy and release of energy. This is called nuclear fusion