 Solution

$B$ removes more blue-green light and appears orange-red; $C$ removes shorter-wavelength blue light and appears yellow. The observed color is the combined transmitted part of the visible spectrum, approximately complementary to the absorbed band, rather than the color corresponding to the absorption maximum itself. The longer-wavelength band of the O-bound nitrito ligand complex therefore shifts the transmitted balance toward orange/red compared with the N-bound nitro ligand complex. Band width, other absorption bands, concentration and optical path length affect the shade and darkness; a single maximum does not quantitatively determine the perceived color.