It is proposed to use liquefied petroleum gas (lpg) in spark-ignition engines. a typical sample of the fuel on a volume basis consists of: 80% propane c3h8, 10% butane c4h10, 10% propene c3h6 the higher heating values of the fuels are 50.38 mj/kg for propane, 49.56 mj/kg for butane, and 48.95 mj/kg for propene. a) show and balance the overall combustion reaction for stoichiometric combustion of 1 mole of lpg with atmospheric air, and determine the stoichiometric f/a and a/f ratios. b) what are the higher and lower heating values per unit mass of lpg?