We know that,

∆G = ∆G° + RTln K… eq (1)

• ∆G = Gibbs free energy

• ∆G° = Standard Gibbs free energy (1atm pressure and 298k)

• T = temperature (in kelvin)

• R = Gas constant

• K = Equilibrium constant

• At Equilibrium, ∆G = 0

∆G° + RTln K = 0

So, RTln K = -∆G°...eq (2)

From the eq (2) we get smaller the magnitude of -∆G°, the higher the rate constant K will be and the faster the reaction.

(i) Equilibrium - (c) ∆G = 0

Explanation: When ∆G is equal to zero and K =1, it means Solution that at Equilibrium, the products and the reactants are equally favoured.

(ii) Spontaneous reaction - (d) ∆G < 0, K >1

Explanation: when ΔG<0, then K >1 i.e. reaction will move in the forward direction and can be used to do some useful work.

(iii) Non spontaneous reaction - (a) ∆G > 0, K < 1

Explanation: when ΔG>0, then K <1 i.e. reaction will move in the backward direction and we need external energy if we want to do some useful work.