CnH2n + 1.5nO2 → nCO2 + nH2O
6X1.5n= 27
n= 3
So , the correct answer is (B) : Propene


Read More: Some Basic Concepts of Chemistry
There are two ways of classifying the matter:
Matter can exist in three physical states:
Based upon the composition, matter can be divided into two main types: