Which gas will be adsorbed to a greater extent on the surface of a solid?

Between water and an $NaCl$ solution,which will have a higher surface tension? (Effect of solute on surface tension)

In the neutralisation of $KI$ by $AgNO_3$,the positive charge on the colloidal particles is due to the adsorption of:

Freundlich adsorption isotherm gives a straight line on plotting :-

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: In expensive scientific instruments,silica gel is kept in watch-glasses or in semipermeable membrane bags.
Reason $(R)$: Silica gel adsorbs moisture from air via adsorption,thus protects the instrument from water corrosion (rusting) and/or prevents malfunctioning.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following is not a characteristic of chemisorption?