Question

Which of the following is not true about adsorption of gases on solids?

• A. As the critical temperature ($T_c$) of a gas increases, it becomes more difficult to liquify it and easier to adsorb it on to a solid
• B. To increase the adsorbing power of an adsorbent, they are sub-divided into smaller pieces. The surface area increases, and the adsorbing power increases
• C. The extent of adsorption of a gas per unit mass of the adsorbent depends on the pressure of the gas
• D. Physical adsorption decreases continuously with an increase in the temperature

Answer 1

The correct option is A As the critical temperature ($T_c$) of a gas increases, it becomes more difficult to liquify it and easier to adsorb it on to a solid

The critical temperature $T_c$ is the temperature at which gases can't be liquefied no matter what the pressure is. i.e., above critical temperature, increase in pressure would not cause liquefication of gases. As the critical temperature of a gas increases, the Vanderwaals forces between them increases , so it becomes easier to liquify and easier to adsorb on a solid.