• In the viewpoint of thermodynamics, Equilibrium can be explained by the following mathematical equation :

∆G = ∆G^⊖ + RTlnQ which comes down to

∆G = ∆G^⊖ + RTlnK and then to

∆G^⊖ = - RTlnK (as at Equilibrium ∆G is zero and Kc is = Q

Now, for the reaction A ⇋ B, at the stage of half completion of the reaction, the concentration of [A] will be equal to [B] i.e. [A] = [B]

Hence, the value of K becomes equal to = =1

The value of ln1 = 0 ,

Hence ∆G^⊖ = - RTlnK = 0

therefore (i) ∆G^⊖ = 0 is the correct answer.