Question

Which of the following statements is incorrect with respect to physisorption?

• A. The forces involved are van der Waal's forces
• B. More easily liquifiable gases are adsorbed easily
• C. Under high pressure it results into multi-molecular layer on adsorbent surface
• D. $\Delta H_{adsorption}$ is low and $+$ve

Answer 1

The correct option is D $\Delta H_{adsorption}$ is low and $+$ve

Adsorption is always exothermic therefore $\Delta H$ is always negative.

Physical adsorption is an exothermic process $(i.e.,\Delta H=–ve)$ but its value is quite low because the attraction of gas molecules and solid surface is weak van der Waals forces.

Hence, option D is an incorrect statement.