(a) Compounds of carbon and hydrogen are called hydrocarbons. Example, methane, ethane etc.
(b) Saturated hydrocarbons contain carbon-
carbon single bonds. Unsaturated
hydrocarbons contain atleast one carbon-
carbon double or triple bond.
(c) Functional group: An atom/group of atoms joined in a specific manner which is responsible for the characteristic chemical properties of the organic compounds. Examples are hydroxyl group (-OH), aldehyde group (—CHO), carboxylic group (—COOH) etc.