(i) Homologous Series: It is defined as group of similar organic compounds which contains the similar functional groups and the two adjacent members of the series are differing by a - CH2 group.
Alkanes CnH2n+2
Alkanes CnH2n
Alkanes CnH2n−2
(ii) Functional Groups: It is an atom or group of atoms bonded together in a unique manner which is usually the site of chemical reactivity in an organic molecule. e.g. CH3OH
General Formula of Carboxylic acids: CnH2n+2 COOH
General formula of acid chlorides: RCOCI