If the bond dissociation energies of $XY, X_2 \: and \: Y_2$(all diatomic molecules) are in the ratio of 1:1:0.5 and $ \Delta H_f $ for the formation of XY is -200 kJ/mol. The bond dissociation energy of $X_2$ will be

Question

$\begin {array} {1 1} (A)\;400\: kJ/mol & \quad (B)\;300\: kJ/mol \\ (C)\;200\: kJ/mol & \quad (D)\;None\: of \: these \end {array}$