Final answer:
Manganese (Mn) exhibits the largest number of oxidation states among the 3d-series transition metals, with possible oxidation states from +2 to +7 due to the removal of s and d orbital electrons.
Step-by-step explanation:
The transition metal from the 3d-series that exhibits the largest number of oxidation states is manganese (Mn). Manganese can have oxidation states ranging from +2 to +7. As a transition metal, manganese has a unique capability to lose electrons from both its s and d orbitals, which contributes to the variety of oxidation states it can exhibit. The d-orbital electrons can be removed more easily in transition metals compared to the s-orbital electrons in alkali and alkaline earth metals.
This means that while alkali metals commonly have an oxidation state of +1 and alkaline earth metals have +2, manganese and other transition metals show a much more complex range of oxidation states. This is due to the variable oxidation state nature of transition metals. Manganese's wide range of oxidation states can be observed in various compounds such as MnO2 (manganese(IV) oxide) and Mn2O7 (manganese(VII) oxide).