CGPET 2021 Solved Paper

In Fe4[Fe(CN)6]3, the counter ion and complex iron has different oxidation state.Fe4[Fe(CN)6]3⟶4Fe3++3[Fe(CN)6]4−
∴ Counter iron will have +3 oxidation state.
∴ In complex ion,
x+6(CN)=−4
x+6(−1)=−4⇒x=+2
∴ In complex, iron has +2 oxidation state.
∴ Oxidation number of iron in Fe4[Fe(CN)6]3 are+3 and +2 respectively