When a gas is adsorbed on solid surface, it follows the equation below:

ΔG = ΔH –TΔS

Here, change in entropy (ΔS) is negative for adsorption, since after adsorption, molecules of adsorbate get more ordered. So (iii) is not applicable.

Since adsorption is a spontaneous process, so it must be accompanied with decrease in free energy. So in adsorption, ΔG is also negative. Therefore, option (ii) is also not applicable.

Now since both ΔS is negative, so TΔS is positive. So for ΔG to be negative, ΔH must be negative. So option (iv) is also not applicable.

Only option (i) is not applied for the process of adsorption. So (i) is the correct answer here.