1. Adsorption isotherms represents the variation of adsorption at constant temperature.
2. When amount f adsorption is plotted versus temperature at constant pressure is called adsorption iso bar
3. In physical adsorption x/m decreases with increase in T. But in chemical adsorption x/m increases with rise in temperature and then decreases. The increase illustrate the requirement of activation of the surface for adsorption is due to the fact that formation of activated complex require certain energy. The decrease at high temperature is due to desorption, as the kinetic energy of the adsorbate increases.