Give reason for the existence of the large number of organic compounds.

Carbon shows unique properties of tetravalency and catenation. Due to this unique nature of carbon atoms, they form single, double and triple covalent bonds with other carbon atoms and a variety of other elements. Carbon atoms have the ability to form stable bonds with other atoms resulting in the formation of long chains, branched structures, and cyclic compounds. These properties of carbon atom gives rise to the formation of a large number of compounds.