Question

Which among the following gases is least adsorbed on solid at similar conditions of temperature and pressure?

• A. $\text{Cl}_{2}$
• B. $\text{NH}_{3}$
• C. $\text{SO}_{2}$
• D. $\text{H}_{2}$

Hint:

Adsorption Extent $\propto$ Critical Temperature ($T_c$) $\propto$ Intermolecular Force Strength $\propto$ Ease of Liquefaction. $\text{SO}_2$ and $\text{NH}_3$ are the undisputed champions of adsorption in standard exam questions!

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The extent of adsorption of a gas on a solid depends on the ease of liquefaction of the gas, which is related to its critical temperature ($T_c$).

Step 2: Formula Application:
Ease of liquefaction $\propto$ Critical Temperature $\propto$ Strength of intermolecular forces.

Step 3: Explanation:
Gases like $NH_3$, $Cl_2$, and $SO_2$ are easily liquefiable because they have higher critical temperatures and stronger intermolecular forces. Hydrogen ($H_2$) is a "permanent gas" with a very low critical temperature and very weak van der Waals forces, making it the least adsorbed.

Step 4: Final Answer:
Hydrogen ($H_2$) is the least adsorbed gas.