Balance each of the following chemical equations. (Use the lowest possible coefficients.) (a) C4H10(g) + O2(g) → CO2(g) + H2O(g) (b) Cr(s) + H2SO4(aq) → Cr2(SO4)3(aq) + H2(g) (c) Cl2O7(g) + Ca(OH)2(aq) → Ca(ClO4)2(aq) + H2O(l) (d) PBr3(l) + H2O(l) → H3PO3(aq) + HBr(g) (e) (NH4)2CO3 + CaSO4 → (NH4)2SO4 + CaCO3 (f) K2SO4(aq) + BaCl2(aq) → BaSO4(s) + KCl(aq) (g) C(s) + Fe2O3(l) → Fe(l) + CO(g) (h) HCl(aq) + FeS(s) → FeCl2(aq) + H2S(g)