Answers:

(a) The Hydrocarbons are basically the compounds of Carbon and hydrogen such as Ethane and Methane.

(b) The Hydrocarbons having single bond is known as saturated hydrocarbons such as Ethane and Methane whereas the hydrocarbons with double or triple bonds are known as unsaturated hydrocarbons such as Ethyne and Ethene.

(c) The set of atoms combined in a certain manner, responsible for the characteristic chemical properties of the compound is called as a functional group such as Aldehyde (CHO), Hydroxyl (OH), Carboxylic acid (COOH).