A hydrocarbon molecule has 3 carbon atoms. Write down its molecular formulae if it is an

(i) alkane

(ii) alkene

(iii) alkyne

a) The molecular formula of alkane having three carbon atoms is C₃H₈ (Propane) . 
b) The molecular formula of alkene having three carbon atoms is C₃H₆ (Propene) .
c) The molecular formula of alkyne having three carbon atoms is C₃H₄ (Propyne).