a, 10FeCl2+6KMnO4+24H2SO4→5Fe2(SO4)3+10Cl2+3K2SO4+6MnSO4+ 24H2O
b, 13Mg+32HNO3→13Mg(NO3)2+1N2+1N2O+1NH4NO3+14H2O
x 13 Mg0 → Mg+2 + 2e-
x 1 5N+5 + 26e-→ N20 + N2+1 + N-3
c, (5x-2y)Fe3O4+(46x-18y)HNO3→(15x-6y)Fe(NO3)3+1NxOy+(23x-9y)H2O
x (5x-2y) 3Fe+8/3 → 3Fe+3 + 1e-
x 1 xN+5 + (5x-2y)e- → xN+2y/x