H2S H(I) S(II)
Fe2O3 Fe(III) O(II)
N2O5 N(V) O(II)
NH3 N(III) H(I)
Cl2O7 Cl(VII) O(II)
OF2 O(II) F(I)
MgO Mg(II) O(II)
а) CH3OH + CuO = Cu + H2O + HCOH
а) HCl + NaOH ==> NaCl + <span>H2O</span>