K2Cr2O7 2(+1)+2x+7(−2)=0 In K2Cr2O7 , Transition metal (Cr) present in +6 oxidation state. KMnO4 (+1)+y+4(−2)=0 x=+7 In KMnO4, transition metal (Mn) present in +7 oxidation state K2FeO4 2(+1)+z+4(−2)=0 x=+6 In K2FeO4, transition metal (Fe) present in +6oxidation state So, x=+6 y=+7 z=+6 ───────── x+y+z=19