The general formula of three compounds $A, B$ and $C$ is $C_{n}H_{2n}$. $B$ has the highest boiling point and $C$ has the lowest boiling point.
$(i)$ Mention the type of compound $A, B$ and $C$.
$(ii)$ Which of these has the minimum number of carbon atoms?
$(iii)$ Name the homologous series to which $A, B$ and $C$ belong.

(C) $(i)$ Compounds $A, B$ and $C$ are unsaturated hydrocarbons containing a carbon-carbon double bond.
$(ii)$ The boiling point of members of a homologous series increases with an increase in molecular mass (i.e.,an increase in the number of carbon atoms). Since compound $C$ has the lowest boiling point,it must have the minimum number of carbon atoms.
$(iii)$ The general formula $C_{n}H_{2n}$ represents the homologous series of alkenes.