To meet the high demand for petrol and petrochemical feedstocks, heavy fractions of crude oil are cracked at high temperatures. In an industrial refinery process, one molecule of hexadecane, C16H34\text{C}_{16}\text{H}_{34}C16H34, is cracked to produce one molecule of ethene, C2H4\text{C}_2\text{H}_4C2H4, two molecules of propene, C3H6\text{C}_3\text{H}_6C3H6, and one other hydrocarbon molecule XXX.
What is the molecular formula of XXX?
C11H24\text{C}_{11}\text{H}_{24}C11H24
C8H16\text{C}_8\text{H}_{16}C8H16
C11H22\text{C}_{11}\text{H}_{22}C11H22
C8H18\text{C}_8\text{H}_{18}C8H18