Ferrous ion (Fe2+) changes to ferric ion Fe3+ on reacting with acidified H2O2 as 2K4[Fe(CN)6]+H2SO4+H2O2→ 2K3[Fe(CN)6]+K2SO4+2H2O Electronic configuration of Fe3+= 1s2,2s2,2p6,3s2,3p6,3d5 Number of d electrons =5 Magnetic moment =√n(n+2) =√5(5+2)=5.92BM