Question

Which of the following gases will substitute $O_2$ from adsorbed charcoal?

• A. $C{l}_2$
• B. $N_2$
• C. $C{H}_4$
• D. All of the above

Answer 1

The correct option is A $C{l}_2$

Adsorption :

The phenomenon of attracting and retaining the molecules of a substance on the surface of a liquid or a solid resulting into a higher concentration of the molecules on the surface is called adsorption. As a result of adsorption, there is a decrease of surface energy. The process of removal of an adsorbed substance from the surface on which it is adsorbed is called desorption. It is the reverse of adsorption and can be brought about by heating or by reducing the pressure.

Adsorption of a gas by charcoal :

Finely divided activated charcoal has a tendency to adsorb a number of gases like ammonia, sulphur dioxide,chlorine, phosgene, etc. In this case, charcoal acts as an adsorbent while gas molecules act as adsorbate.

Activated powdered charcoal used in the gas mask which is exposed to the atmospheric air so that gases and water vapours in air are adsorbed on its surface.
In general, easily liquifable gases such as $C{O}_2,N{H}_3,C{l}_2$, and $S{O}_2$ are adsorbed to a greater extent than the elemental gases. For example: $H_2,N_2,O_2,He$ etc.

Hence,
when the mask is exposed to chlorine atmosphere, the gases are displaced by chlorine.