Problem (IIT JEE 2008):
Assume that the nuclear binding energy per nucleon $(B/A)$ versus mass number $(A)$ is as shown in the figure. Use this plot to choose the correct choice(s) given below,
Solution: If $B/A$ of the products is more than that of the reactants than energy is released in the reaction. Fusion of two nuclei with mass number in $1 < A < 50$ produces a nuclei with mass number in $1 < A < 100$. The $B/A$ of product is equal to that of reactants, hence no energy is released.
Fusion of two nuclei with mass number in $51 < A < 100$ produces a nuclei with mass number in $100 < A < 200$. The $B/A$ of product is more than that of reactants, hence energy is released.
The fission of nucleus with mass number $100 < A < 200$ produces products with mass number lying in $1 < A < 200$. The $B/A$ of products is less than or equal to that of reactants hence no energy is released. The fission of nucleus with mass number $200 < A < 260$ produces products with mass number lying in $100 < A < 200$. The $B/A$ of products is more than that of the reactants, hence energy is released.