Question

The curve in the figure shows the binding energy per nucleon versus mass number for four nuclei W, X, Y and Z. The process that would release energy is

(1) Y→2Z

(2) W→X+Z

(3) W→2Y

(4) X→Y+Z

Answer 1

(3) W→2Y

We know that energy is released when the total binding energy of products is more than the rectants. 

In option (3) we find that. 

Binding energy of reactants = 120x7.5 = 900 MeV 

Binding energy of products = 260x8.5 = 1020 MeV 

Thus 1020 MeV > 900 MeV and this process would release energy. 

In option 1 

B.E of reactants = 60x7.5 = 450 

B.E of products = 2 (30x50) = 300 

Not possible Similar is the case for process (2) and (4).