\( \mathrm{A_2} + \mathrm{B_2} \rightarrow 2\mathrm{AB} \). \( \Delta H^{0}_f = -200 \, \text{kJ mol}^{-1} \)
AB, \( \mathrm{A_2} \) and \( \mathrm{B_2} \) are diatomic molecules. If the bond enthalpies of \( \mathrm{A_2} \), \( \mathrm{B_2} \) and AB are in the ratio \( 1 : 0.5 : 1 \), then the bond enthalpy of \( \mathrm{A_2} \) is _____ \( \text{kJ mol}^{-1} \). (Nearest integer)
