d
\(\mathrm{X}^{240} \rightarrow \mathrm{Y}^{120} \rightarrow \mathrm{Z}^{120}\)

given binding energy per nucleon of \(X, Y \& Z\) are

\(7.6\, \mathrm{MeV}, 8.5\, \mathrm{MeV} \,\&\, 8.5\, \mathrm{MeV}\) respectively.

Gain in binding energy is:

\(\mathrm{Q}=\) Binding Energy of products \(-\) Binding energy of reactants

\(=(120 \times 8.5 \times 2)-(240 \times 7.6)\, \mathrm{MeV}\)

\(=216\, \mathrm{MeV}\)