The correct answer is (d) ΔS > 0
Easiest explanation: Physisorption is reversible as the molecules of the adsorbate are held to the adsorbent by weak Van der Waals forces which can be broken easily. Physisorption is exothermic and so, ΔH is negative. Adsorption is a spontaneous process. In adsorption, the movement of the adsorbed molecule is restricted. As a result the entropy change (ΔS) is negative.