а) Цинк2Zn+O2=2ZnOZn(0)-2e=Zn(+2)O2(0)+4e=2O(-2)Zn+S=ZnSZn(0)-2e=Zn(+2)S(0)+2e=S(-2)Zn+2HCl=ZnCl2+H2Zn(0)-2e=Zn(+2)2H(+)+2e=H2(0)Zn+4HNO3=Zn(NO3)2+2NO2+2H2OZn(0)-2e=Zn(+2)N(+5)+1e=N(+4)4Zn+5H2SO4=4ZnSO4+H2S+4H2OZn(0)-2e=Zn(+2)S(+6)+8e=S(-2)Zn+2NaOH+2H2O=Na2[Zn(OH)4]+H2Zn(0)-2e=Zn(+2)2H(+)+2e=H2(0)Zn+FeSO4=ZnSO4+FeZn(0)-2e=Zn(+2)Fe(2+)+2e=Fe(0)б)Медь2Cu+O2=2CuOCu(0)-2e=Cu(+2)O2(0)+4e=2O(-2)Cu+S=CuSCu(0)-2e=Cu(+2)S(0)+2e=S(-2)Cu+4HNO3(конц.) =Cu(NO3)2+2NO2+2H2O Cu(0)-2e=Cu(+2)N(+5)+1e=N(+4)Cu+2H2SO4=CuSO4+SO2+2H2OCu(0)-2e=Cu(+2)S(+6)+2e=S(+4)