KCET 2016 Chemistry Solved Paper

Physisorption is an exothermic process but, its enthalpy ofadsorption is low, because attractive forces between adsorbent and the adsorbate molecules are weak (i.e., van der Waals forces) and therefore, molar enthalpy (ΔH) of adsorption is low and is of the order of 20−40‌kJ‌mol–1.Maximum of gas is adsorbed when pressure is increased as the volume of gas decreases. The gases which are easily liquefied are adsorbed readily, because van der Waals forces are stronger near the critical temperature.