Question

Write the molecular formulae of the third and fifth members of homologous series represented by the general formula C_nH_2n−2.

Answer 1

The general formula for unsaturated hydrocarbon alkyne is C_nH_2n−2, where n is the number of carbon atoms in one molecule of the alkyne.
For the third and fifth members of homologous series of alkyne family, n = 4 and n = 6 respectively. The corresponding molecular formulae will be:

n	General Formula CnH2n−2	Molecular Formula
4	C2H2(4)−2	C4H6
6	C2H2(6)−2	C6H10