Select the correct answer from each drop-down menu. Why do some transition metals have multiple oxidation states?

Transition metals have multiple oxidation states because of their (a. completely filled b. partially filled c. empty) (s, p, d, or f) sublevel.

because of energy difference between (n1)d and ns orbitals (sub levels) and involvement of both orbital in bond formation

Explaination:

the reason is that there is a difference in energy of orbitals of an atom of transition metal, so there (n1)d orbitals and there ns orbitals both make a bond and for this purpose they lose an electron that is why both sublevels shows different oxidation state.  

Hope this helped you

Transition metals have multiple oxidation states because of their  

[ partially filled ] [ d ] sublevel.

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).