Which statements among the following are correct? (i) Freundlich isotherm fails at high pressure of the gas. (ii) ΔH < 0 for both physical and chemical adsorption. (iii) Physical adsorption is non-selective. (iv) Chemical adsorption is reversible, where as physical adsorption is irreversible.

Step-by-step solution

According to the Freundlich isotherm, thevariation of extent of adsorption ( x / m ) with pressure ( P ) was given mathematically by Freundlich.Where 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. x m = kP 1 n At very high pressure, x m = 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