Question

Write the molecular formula of the 2^nd and the 3^rd member of the homologous series whose first member is methane.

Answer 1

The general formula for the homologous series whose first member is methane is C_nH_2n+2.

The two consecutive members (2nd and 3rd) of this series are: 

a. CH₃CH₃ (Ethane); where n is 2 

b. CH₃CH₂CH₃(Propane); where n is 3

The molecular formulae are C₂H₆ and C₃H₈ respectively.