A gaseous hydrocarbon gives upon combustion 0.72 g of water and 3.08 g of CO2. The empirical formula of the hydrocarbon is:
General equation for combustion of hydrocarbon :
Number if moles of CO2 produced = 3.08 / 4 = 0.07
Number of moles of H2O produced = 0.72 / 18 = 0.04
So,
The formula of hydrocarbon is C7H8.