Adsorption of a gas follows Freundlich adsorption isotherm. If x is the mass of the gas adsorbed on mass m of the adsorbent, the correct plot of x/m versus p is:

Freundlich gave an empirical relationship between the quantity of gas adsorbed by a unit mass of solid adsorbent and pressure at a constant temperature. The Freundlich adsorption isotherm law states that the change in the amount of gas absorbed by unit mass of a solid is directly proportional to the change in the pressure at a given temperature.

Freundlich equation

$\frac{x}{m}=K{P}^{\frac{1}{n}}----------------\left(I\right)$

Where,

x = mass of the adsorbent at pressure P

k = constant

The relationship is generally represented in the form of a curve where mass of the gas adsorbed per gram of the adsorbent is plotted against pressure. These curves indicate that at a fixed pressure, there is a decrease in physical adsorption with increase in temperature. These curves always seem to approach saturation at high pressure.

Therefore, option C is correct.