Question

Which of the following statements is incorrect regarding physisorption?

• A. It occurs because of van der Waals forces
• B. Liquefiable gases are adsorbed more easily
• C. Enthalpy of adsorption $\left(\Delta H_{adsorption}\right)$ is high and negative
  
• D. Enthalpy of adsorption $\left(\Delta H_{adsorption}\right)$ is low and positive

Answer 1

Answer: (C), (D)

The correct options are
C Enthalpy of adsorption $\left(\Delta H_{adsorption}\right)$ is high and negative
D Enthalpy of adsorption $\left(\Delta H_{adsorption}\right)$ is low and positive

For physisorption, the enthalpy of adsorption $\left(\Delta H_{adsorption}\right)$ is low and negative.
Its value is -20 to -40 kJ/mol.

Note:
Physisorption occurs because of the presence of van der Waals forces between adsorbent and adsorbate molecules.

Liquefiable gases are adsorbed more easily as they have strong intermolecular attractive forces.

Hence, the correct answers are $\text{C}$ and $\text{D}$