Which of the following statements is true for physical adsorption?

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

Which of the following is not a characteristic of chemisorption?

The correct statement$(s)$ pertaining to the adsorption of a gas on a solid surface is (are):
$(A)$ Adsorption is always exothermic.
$(B)$ Physisorption may transform into chemisorption at high temperature.
$(C)$ Physisorption increases with increasing temperature but chemisorption decreases with increasing temperature.
$(D)$ Chemisorption is more exothermic than physisorption,however it is very slow due to higher energy of activation.

During the adsorption of a gas on a solid at low temperature,which of the following thermodynamic conditions is correct?

Charcoal is mixed in $500 \ mL$ of $0.5 \ M$ acetic acid solution. After some time,the concentration of the solution becomes $0.3 \ M$. Find the total number of molecules adsorbed on the surface of the charcoal.