Question

Which one of the following is/are correct statement(s) for physisorption?

• A. It is a reversible process
• B. It requires less heat of adsorption
• C. It requires activation energy
• D. It takes place at low temperature

Answer 1

Answer: (A), (B), (D)

The correct options are
A It is a reversible process
B It requires less heat of adsorption
D It takes place at low temperature

Physical adsorption is the adsorption in which the forces of attraction between the molecules of the adsorbate and the adsorbent are of the weak van der Waals' type. Physical adsorption is multilayer, non-directional, and non-specific.

Since the forces of attraction are weak, the process of physisorption
can be easily reversed (solvent may be adsorbed in preference to the solute on the surface of the adsorbent) by heating or decreasing the pressure of the adsorbate (as in the case of gases).

Physical adsorption usually takes place at low temperature and decreases with increase in temperature.
Chemical adsorption decreases with increase in temperature.

Physisorption does not require activtion energy.

Hence,C is incorrect.

Thus option A,B and D are correct.