Read the following passage and answer the questions.
Adsorption is surface phenomenon and its differ from absorption, 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 absorbent and absorbate. Generally, easily liquifying gases are absorbed more easily on the surface of a solid as compared to the gases which are liquified with difficulty. Adsorption increases with the increase in pressure and decreases as the temperature is increased.
Is the process of adsorption exothermic or endothermic ?