The energies of activation for forward and reverse reactions for A2 + B2 ⇋ 2AB are 180kJ mol–1 and 200kJ mol–1 respectively. The presence of a catalyst lowers the activation energy of both (forward and reverse) reactions by 100kJ mol–1. The enthalpy change of the reaction (A2 + B2 → 2AB) in the presence of a catalyst will be (in kJ mol–1 )
(a) 20
(b) 300
(c) 120
(d) 280.