The volumes of gases $H_2, CH_4, CO_2$ and $NH_3$ adsorbed by $1 \ g$ of charcoal at $288 \ K$ are in the order:

To form a complete monolayer of acetic acid on $1 \ g$ of charcoal,$100 \ mL$ of $0.5 \ M$ acetic acid was used. Some of the acetic acid remained unadsorbed. To neutralize the unadsorbed acetic acid,$40 \ mL$ of $1 \ M$ $NaOH$ solution was required. If each molecule of acetic acid occupies $P \times 10^{-23} \ m^2$ surface area on charcoal,the value of $P$ is $\qquad$
[Use given data : Surface area of charcoal $= 1.5 \times 10^2 \ m^2 \ g^{-1}$; Avogadro's number $(N_A) = 6.0 \times 10^{23} \ mol^{-1}$]

The Freundlich adsorption isotherm gives a straight line on plotting:

Noble gases are adsorbed on

In Langmuir's model of adsorption of a gas on a solid surface:

Why does physical adsorption decrease with an increase in temperature?