(a) Adsorption may or may not involve the formation of bond between adsorbent and adsorbate.
(b) At high pressure, the Freundlich isotherm acquires a form $\frac{x}{m} \propto p$
(c) Physisorption involves formation of multimolecular layers.
(d) Adsorption involves the concentration of one substance over the surface of other.
