Final answer:
The conversion of a violet solution of vanadium(II) ions to a green solution of vanadium(III) ions signifies that vanadium(II) has undergone oxidation, as it loses an electron and increases its oxidation state from +2 to +3.
Step-by-step explanation:
When a violet solution of vanadium(II) ions, V²⁺(aq), is converted to a green solution of V³⁺(aq), the vanadium(II) ions undergo oxidation.
Oxidation refers to the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. In this case, vanadium(II) ions, which had an initial oxidation state of +2, are oxidized to vanadium(III) ions with an oxidation state of +3, losing one electron in the process.