① Cu+HNO3﹣ Cu(NO3)2+ NO↑+H2O
②KMnO4+K2SO3+H2O﹣MnO2+K2SO4+KOH
③Fe(OH)3+NaOH+Cl2﹣Na2FeO4+NaCl+H2O
④H2O2+Cr2(SO4)3+﹣K2SO4+K2CrO4+H2O.