What is adsorption,adsorbate,adsorbent and desorption? Explain with appropriate examples.

(N/A) Adsorption: The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed adsorption.
Adsorbate: The molecular species or substance,which concentrates or accumulates at the surface is termed adsorbate. e.g.,particles of colour.
Adsorbent: The material on the surface of which the adsorption takes place is called adsorbent. e.g.,charcoal,silica gel,alumina gel,clay,colloids,metals in finely divided state.
Desorption: The process of removing an adsorbed substance from a surface on which it is adsorbed is called desorption.
It is clear from the above examples that solid surfaces can hold the gas or liquid molecules by virtue of adsorption.
Some examples of adsorption process are as under:
$(i)$ If a gas like $O_2$,$H_2$,$CO$,$Cl_2$,$NH_3$ or $SO_2$ is taken in a closed vessel containing powdered charcoal,it is observed that the pressure of the gas in the enclosed vessel decreases. The gas molecules concentrate at the surface of the charcoal,i.e.,gases are adsorbed at the surface.
$(ii)$ In a solution of an organic dye,say methylene blue,when animal charcoal is added and the solution is well shaken,it is observed that the filtrate turns colourless. The molecules of the dye,thus,accumulate on the surface of charcoal,i.e.,are adsorbed.
$(iii)$ Aqueous solution of raw sugar when passed over beds of animal charcoal becomes colourless as the colouring substances are adsorbed by the charcoal.
$(iv)$ The air becomes dry in the presence of silica gel because the water molecules get adsorbed on the surface of the gel.