The correct statement(s) pertaining to the adsorption of a gas on a solid surface is (are)

Options

A. a. Adsorption is always exothermic
B. b. Physisorption may transform into chemisorption at high temperature
C. c. Physisorption increases with increasing temperature but chemisorption decreases with increasing temperature
D. d. Chemisorption is more exothemic than plıysisorption, however, it is very slow due to higher energy of activation.

Answer

A, B, D

Explanation

A,B,D
A) Adsorption is an exothemic process.
B) For example, dihydrogen is first adsorbed on Ni by van der Waals forces. At high temperature, molecules of hydrogen then dissociate to form Hatoms, which are held on the surface by chemisorption.
C) Chemisorption increases with increase of temperature.
D) Energy of adsorption is high-in chemisorption `(80-240 kJ mol^(-1))` as compared to physisorption `(20-40 kJ mot^(-1))`.