GKFix MCQ Question

Why do the complexes [Fe(CN)6]^4- and [Fe(CN)6]^3- have different colors in solution?

• A. Because CN- is a ligand.
• B. Because Fe has different oxidation states.
• C. Because they are both iron complexes.
• D. Because the different charges on the complexes ([Fe(CN)6]^4- vs [Fe(CN)6]^3-) lead to slightly different ligand field environments and crystal field splitting energies, absorbing different wavelengths of light.