$\mathrm{A}_{2}+\mathrm{B}_{2} \rightarrow 2 \mathrm{AB} . \Delta H_{f}^{0}=-200 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$\mathrm{AB}, \mathrm{A}_{2}$ and $\mathrm{B}_{2}$ are diatomic molecules. If the bond enthalpies of $\mathrm{A}_{2}, \mathrm{~B}_{2}$ and $\mathrm{AB}$ are in the ratio $1: 0.5: 1$, then the bond enthalpy of $\mathrm{A}_{2}$ is ____________ $\mathrm{kJ} ~\mathrm{mol}^{-1}$ (Nearest integer)