Chemical Bonding And Molecular Structure

Bond enthalpies of \(A_2, B_2\) and \(A B\) are in the ratio \(2: 1: 2\). If bond enthalpy of formation of \(A B\) is \(-100 \mathrm{~kJ} \mathrm{~mol}^{-1}\). The bond enthalpy of \(B_2\) is