Which one of the following is not applicable to chemisorption?

Given below are two statements. One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A :$ Activated charcoal adsorbs $SO_{2}$ more efficiently than $CH_{4}$.
Reason $R$ : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In the light of the above statements,choose the correct answer from the options given below.

The principle of $Adsorption$ is used in which of the following purification methods?

Which one is the irreversible adsorption?

If $x$ is the mass of the gas adsorbed on mass $m$ of the adsorbent at pressure $p,$ Freundlich adsorption isotherm gives a straight line on plotting

Which of the following phenomena is exhibited by adsorption?