If the bond dissociation energies of the diatomic molecules $XY, X_2$ and $Y_2$ are in the ratio of 1 : 1 : 0.5 and $\Delta_fH$ for the formation of XY is -200 kJ $mol^{-1}$. What is the bond dissociation energy of $X_2$ will be

Question

(a) 100 kJ $mol^{-1}$
(b) 200 kJ $mol^{-1}$
(c) 800 kJ $mol^{-1}$
(d) 400 kJ $mol^{-1}$