<p>At 300 K and 1 atm, 15 mL of a gaseoud hydrocarbon requires 375 mL air containing 20%&nbsp;<math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>O</mi><mn>2</mn></msub></math>&nbsp;by volume for complete combustion. After combustion the gases occupy 330 mL. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is:</p>