Question

# Given that Gas ${{H}_{2}},C{{H}_{4}},C{{O}_{2}},S{{O}_{2}}$Critical temperature (K) 33, 190, 304, 630On the basis of data given above, predict which of the following gases shows least adsorption on a definite amount of charcoal.A. ${{H}_{2}}$ B. $C{{H}_{4}}$ C. $S{{O}_{2}}$ D. $C{{O}_{2}}$

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Hint: In solid the amount of gas that is adsorbed depends upon the nature of the gas. The gas which is easily liquefiable will be easily adsorbed. The extent of adsorption depends upon the value of critical temperature. Lesser will be the value of critical temperature of gases. The value of adsorption will also be less.

Complete step by step solution:
-Adsorption is defined as the process in which molecules are deposited on the surface. Adsorbate are the molecular species that get absorbed onto the surface and adsorbent is known as the surface on which adsorption is taking place. In adsorption molecules (adsorbate) tend to travel from liquid or gas phases and form a monomolecular layer on the liquid or solid condensed phase.
-In adsorption we use activated charcoal which is a form of carbon with small and low volume pores which increases the surface area for the adsorption. Activated charcoal is a good adsorbent because it provides large surface area for the adsorption of contaminants and they are highly porous. Gases or liquids that are passed through this charcoal bind chemically with the exposed carbon through adsorption and fill the active sites.
-In solid the amount of gas that is adsorbed depends upon the nature of the gas. The gas which is easily liquefiable will be easily absorbed by the charcoal. Charcoal has the ability to strongly adsorb those gases which are easily liquefiable.
-The extent of adsorption also depends upon the value of critical temperature. Higher the critical temperature maximum will be the adsorption. Lesser will be the value of critical temperature of gases, the value of adsorption will also be less. In the question the values of critical temperature are given so among them the least critical temperature is of ${{H}_{2}}$ which is 33. Hence it will show least adsorption.

Thus the correct option will be (A).

Note: Adsorption and absorption are two different phenomena. Adsorption is the surface phenomenon whereas absorption is the bulk phenomenon in which the molecules of absorbate enters in the absorbent. Unlike absorption in adsorption molecules of the adsorbate remains on the surface of the adsorbent. Activated charcoal and charcoal are different because activated charcoal is produced at higher temperature and is much porous than charcoal.