`[Fe(CN)_(6)]^(4-) and [Fe(H_(2)O)_(6)]^(2+)` are of different coloures in dillute solutions. Why ?

Explanation

In both octahedral complexes central metal ion `(Fe^(2+))` has electronic configuration `3d^(2)` i.e., it has 4 unpaired field energies `(Delta_(0))`, and hence the respective complexes absorb different components of the visible light (VIBGYOR) for electronic `d-d` transitions. So the transmitted colour would be different i.e., the colour of the complexes would be different.