Explain why hexacayano complexe of metals in their +2 oxidation state are usually yellow , but the corresponding hexa aqua compounds are often blue or green .

Options

A. hexacyano complexes absorb orange or red light thus appear yellow while hexaaqua complexes absorb indigo thus appear yellow
B. hexacyano complexes absorb indigo thus appearing yellow while hexaaqua complexes absorb orange or red light thus appear blue or green
C. hexacyano complexes absorb yellow light while hexaaqua complexes absorb blue light
D. `CN^(-)` ions are yellow in colour while aqua ions are blue or green in colour .

Answer

D