Question -
Answer -
Thecolour of a particular coordination compound depends on the magnitude of thecrystal-field splitting energy, Δ. This CFSE in turn depends on the nature ofthe ligand. In case of [Fe(CN)6]4− and[Fe(H2O)6]2+,the colour differs because there is a difference in the CFSE. Now, CN− isa strong field ligand having a higher CFSE value as compared to the CFSE valueof water. This means that the absorption of energy for the intra d-d transitionalso differs. Hence, the transmitted colour also differs.