Define adsorption with an example. Why is adsorption exothermic in nature? Write the types of adsorption based on the nature of forces between adsorbate and adsorbent.

Adsorption is the accumulation of molecular species on the surface of a solid or a liquid. Eg: When a chalk piece is dipped in ink,the molecules of ink are adsorbed on the surface of the chalk.
Adsorption unbalanced residual forces.This causes a decrease in surface energy and thus,adsorption is exothermic.
Types of adsorption based on nature of forces between adsorbent and adsorbate:
Physisorption: Force acting b/w adsorbent and adsorbate is weak vanderwaals force.
Chemisorption:  Force acting b/w adsorbent and adsorbate is strong force,ie,chemical bond.