Incorrect Statement Regarding Adsorption of Gases on a Solid Surface

Introduction:
Adsorption is a surface phenomenon where a gas or a liquid gets accumulated on the surface of a solid or a liquid respectively. Adsorption is a reversible process where the adsorbate (gas or liquid) gets adsorbed on the surface of the adsorbent (solid or liquid) due to the attractive forces between them.

Enthalpy of Adsorption:
The enthalpy of adsorption is the heat of adsorption which is the amount of heat released or absorbed during the adsorption process. It is negative for physical adsorption and positive for chemical adsorption. Physical adsorption is a weak adsorption process where there are weak van der Waals forces between the adsorbate and the adsorbent. The enthalpy of adsorption is negative in physical adsorption because heat is released during the process which means that the adsorption process is exothermic.

Entropy of Adsorption:
The entropy of adsorption is the measure of the increase in disorder or randomness of the system during the adsorption process. It is negative for physical adsorption and positive for chemical adsorption. The entropy of adsorption is negative in physical adsorption because there is a decrease in the randomness of the system during the adsorption process which means that the adsorption process is not favorable.

Residual Forces on the Surface:
On adsorption, the residual forces on the surface are increased. This is because the adsorbate molecules are attracted to the surface of the adsorbent due to the van der Waals forces between them. The adsorbate molecules get accumulated on the surface of the adsorbent and form a thin layer. This layer of adsorbate molecules exerts a force on the surface of the adsorbent which increases the residual forces on the surface.

Decrease in Surface Energy:
On adsorption, a decrease in surface energy appears as heat. This is because the adsorbate molecules release energy as heat when they get adsorbed on the surface of the adsorbent. This release of energy is due to the formation of new intermolecular forces between the adsorbate and the adsorbent.

Incorrect Statement:
The incorrect statement among the given options is option C which states that on adsorption, the residual forces on the surface are increased. The correct statement is that on adsorption, the residual forces on the surface are decreased because the adsorbate molecules form new intermolecular forces with the surface of the adsorbent which reduces the residual forces on the surface.