Since physisorption arises mainly because of van der Waals forces, it means adsorption is: (pick the incorrect option)

Enthalpy dependent

Physisorption is a type of adsorption in which the adsorbate (the gas or liquid being adsorbed) and the adsorbent (the solid surface) are held together by weak van der Waals forces. Physisorption is a non-specific process, meaning that any gas molecule can be adsorbed on any solid surface. Physisorption is also reversible, meaning that the adsorbate can be easily removed from the adsorbent by increasing the temperature or decreasing the pressure. Physisorption is typically a multimolecular process, meaning that multiple layers of adsorbate molecules can form on the adsorbent surface. The enthalpy of physisorption is typically low, meaning that not much energy is released when the adsorbate physisorbs on the adsorbent.

Therefore, the incorrect option is (4) Enthalpy dependent.

The other options are all correct:

(1) Non-specific in nature

(2) Reversible in nature

(3) Multimolecular in layer

Here is a summary of the characteristics of physisorption:

• Non-specific
• Reversible
• Multimolecular
• Low enthalpy
• Weak van der Waals forces