Final answer:
The stable oxidation states for transition elements with electron configurations 3d³, 3d⁵, 3d⁸, and 3d⁴ are generally +3 for 3d³, +2 or +3 for 3d⁵ (due to the stability of half-filled d sublevel), +2 or +3 for 3d⁸, and +2 or +3 for 3d⁴, as transition metals show a broad range of oxidation states.
Step-by-step explanation:
The stable oxidation states of transition elements with electron configurations 3d³, 3d⁵, 3d⁸, and 3d⁴ in their ground state can be deduced from general rules. The transition metals possess multiple oxidation states largely due to the ease with which the d-orbital electrons can be removed. Elements in the beginning of the transition series tend to have higher oxidation states as they can lose both s and d orbital electrons.
For an element with a 3d³ electron configuration, the stable oxidation state might be +3, reflecting the loss of the two 4s and one 3d electrons. A configuration of 3d⁵ is peculiar because half-filled d-sublevels (3d⁵) are particularly stable, so +5 could be possible, but more commonly seen are the +2 and +3 states when the 4s electrons and possibly one 3d electron are removed. For the 3d⁸ configuration, the stable states could be +2 or +3, after losing the 4s electrons and possibly one 3d electron. An atom with a 3d⁴ configuration would likely have a +2 or +3 oxidation state after losing its 4s electrons and one 3d electron, respectively.