Why might it be handy to know the colors associated with different oxidation states of certain ions?

although scandium is a member of the d block, its ion (Sc3+) hasn't got any d electrons left to move around. This is no different from an ion based on Mg2+ or Al3+. Scandium(III) complexes are colourless because no visible light is absorbed.In the zinc case, the 3d level is completely full - there aren't any gaps to promote an electron in to. Zinc complexes are also colourless.So thats why it be handy to know the colors associated with different oxidation states of certain ions

shield volcanos are angry and get mad over the smallest things so much that there heads erupt   pahoehoe and a'a lava. a composite volcano is the poller opposite of a shield volcano. its   peaceful thing and knows how to control its emotions.      

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.