What are addition reaction? What are catalysts? Illustrate with an example.

Explanation

Reactions which involve addition of two reactants to form a single product aren called addition reactions. Catalysts are the substances which can change, usually increase the speed of a chemical reaction without being used up in that reaction.
For example, vegetable oils having long unsaturated carbon chains are converted into vegetable ghee by heating them in presence of Nickel, platinum or palladium metals used as catalysts.
`underset("(Liquid)")("Vegetable oil"+ H_2) overset("Nickel 48 K")to underset("Solid")("Vegetable Ghee")`