The energies of activation for forward and reverse reaction for  $A_2+B_2\rightleftharpoons 2AB$ are $180 \mathrm{kJ}mo{l}^{-1}$  and $200\mathrm{kJ}{\mathrm{mol}}^{-1}$ respectively. The presence of catalyst lowers the activation energy of both (forward and reverse) reactions by  $100 \mathrm{kJ} mo{l}^{-1}$ . The enthalpy change of the reaction  $\left(A_2+B_2\to 2AB\right)$ in the presence of catalyst will be $\left(in kJ mo{l}^{-1}\right)$