Question

A particular adsorption process has the following characteristics : (i) It arises due to van der Waals forces and (ii) it is reversible. Identify the correct statement that describes the above adsorption process :

• A. Adsorption is monolayer
• B. Energy of activation is low
• C. Adsorption increases with increase in temperature
• D. Enthalpy of adsorption is greater than 100 kJ mol${}^{-1}$

Answer 1

Answer: (B)

Energy of activation is low

Physical adsorption process (physisorption) has the following characteristics : (i) It arises due to van der Waals forces and (ii) it is reversible. The correct statement that describes the above adsorption process is option B. Energy of activation for physisorption is low.
Physisorption is multilayer. It decreases with increase in temperature and the enthalpy of physisorption is low $(20-40$ kJ/mol$)$.