配平下列化学方程式:(1)______NH3+______Cl2═______ N2+______ NH4Cl(2)______FeS2+______O2═______ Fe2O3+______ SO2(3)______C3H8+______O2═______CO2+______ H2O(4)______N2O3+______Fe═______ Fe3O4+______ N2.