how do i solve this?
10cm3 of a gaseous hydrocarbon was mixed with excess oxygen and ignited. The gas volumes were measured at room temperature and pressure before and after combustion and it was found that the total gas volume had contracted by 20 cm3 . Given that combustion was complete, the formula of the hydrocarbon was
A C4 H4
B C4 H6
C C4 H8
D C4 H10