According to the Freundlich isotherm, thevariation of extent of adsorption $(\mathrm{x}/\mathrm{m})$ with pressure $\left(\mathrm{P}\right)$ was given mathematically by Freundlich.Where $\mathrm{n}$ can take any whole number value which depends uponthe nature of adsorbate and adsorbent. The above relationship is
also called Freundlich’s adsorption isotherm.

$\frac{\mathrm{x}}{\mathrm{m}}={\mathrm{kP}}^{\frac{1}{\mathrm{n}}}$

At very high pressure, $\frac{\mathrm{x}}{\mathrm{m}}=\mathrm{k}$, it is independent of the pressure.

Physical adsorption (i.e. physisorption) :-

When the particles of the adsorbate are held to the surface of the adsorbent by the physical forces such as van der Waal’s forces, the adsorption is called physical adsorption or vanderwaals adsorption. Physical adsorption is non-selective. It is reversible and occur rapidly. It has the $∆\mathrm{H}<0$.
Chemical adsorption (i.e. chemisorption) :-
When the molecules of the adsorbate are held to the surface of the adsorbent by the chemical forces, the adsorption is called chemical adsorption. It is irreversible and occur slowly. It has the $∆\mathrm{H}<0$.

Hence, the statements $\left(\mathrm{i}\right),\left(\mathrm{ii}\right)\&\left(\mathrm{iii}\right)\mathrm{only}$ are correct.