Answer.
• All members of a series can be represented by a general formula for example, general formula of alkane, alkenes and alkynes are CnH2n +2, CnH2n and CnH2n -2 respectively.
• Successive members of the series differ by one unit of -CH2- and a mass of 14 amu.
• They have similar chemical properties because they contain the same functional group.
• There is a regular change in their physical properties; the melting and boiling points increase gradually with the increase of molecular masses.
• They can be prepared by similar general methods.
Hydrocarbons are regarded as parent organic compounds. All other compounds are considered to be derived from them by substituting one or more hydrogen atoms of a hydrocarbon by one more reactive atom or group of atoms.