Adsorption is a surface phenomenon and it differs feom adsorption which occurs throughout the body of the substance which absorbs. In physisorption, the attractive forces are mainly van der Waals' forces while in chemisorption actual bonding occurs between the particles of adsorbent and adsorbente. Generally, easily liquefying gases are adsorbed more easily on the surface of a solid as compared to teh gases whihc are liquefied with difficult. Adsorption increases with the increases in pressure and decreases as the temperature is increases.
Freunlich adsorption isotherm gives a straight line on plotting :