The substance used to decolourise and purify oils is

The rate of physical adsorption:

For the adsorption of a gas on a solid,the plot of $\log(x/m)$ versus $\log P$ is linear with slope equal to

Which one of the following statements is correct?

Assertion $(A)$: Adsorption is an exothermic process.
Reason $(R)$: Physisorption of a gas on a solid surface is normally reversible.

Assertion $(A)$: van der Waals' forces are responsible for chemisorption.
Reason $(R)$: High temperature is favourable for chemisorption.
The correct answer is