At equilibrium, in adsorption process, the change in free energy ΔG= 0.

We know, ΔG= ΔH – TΔS

So for ΔG= 0, ΔH= TΔS

Therefore, (ii) is correct.

In options (iii) and (iv), ΔH is not equal to TΔS. So both are wrong options.

Adsorption process at equilibrium is not accompanied with an increase in enthalpy. So (i) is not correct.