a) NH3, H2SO4, S, NaOH, N2, Al, Al2O3, F2, HF, Na;
б) C, CH4, HNO3, O2, H2, Mg, HCl, CuO, FeSO4, C
в) H2S, H, SiO2, Fe, Zn, ZnCl2, Na2CO3. Br2, O2, NaCl.