Question

Extent of physisorption of a gas increases with ___________.
(i) increase in temperature.
(ii) decrease in temperature.
(iii) decrease in surface area of adsorbent.
(iv) decrease in strength of van der Waals forces.


NCERT Class XII
Chemistry - Exemplar Problems

Chapter 5. Surface Chemistry

Answer 1

(ii) decrease in temperature...........is the answer

Answer 2

Answer: (ii) decrease in temperature.

Explanation: Physisorption occurs when a gas is held by the surface of a solid by weak vanderwaals forces without resulting into formation of chemical bond.

Physisorption decreases with increase in temperature as the gas molecules start leaving the surface of adsorbent by gaining kinetic energy.

Decreasing the surface area of adsorbent decreases the amount of gas adsorbed.

Decrease in strength of vanderwaals forces also decrease the extent of physisorption.

Thus extent of physisorption of a gas increases with decrease in temperature.