Consider the following reversible reaction, A(g) + B(g) ⇌  AB(g). The activation energy of the backward reaction exceeds that of the forward reaction by 2RT (in J mol−1 ). If the pre-exponential factor of the forward reaction is 4 times that of the reverse reaction, the absolute value of ΔGθ (in mol−1) for the reaction at 300K is____(Given ; ln (2) = 0.7, RT = 2500 J mol−1 at 300 K and G is the Gibbs energy)