Final answer:
The element being oxidized in the redox reaction provided is not explicitly indicated, but based on common redox reactions involving manganese and ammonia, it is reasonable to conclude that NH₄⁺ (ammonium) is the species being oxidized as it would be losing electrons.
Step-by-step explanation:
The element being oxidized in the given redox reaction Mn₂+(aq) + NH₄ +(aq) → Mn(s) + NO₃ - (aq) is not explicitly stated in the provided chemical equation.
However, based on the information provided about different redox reactions, we can deduce that Mn (manganese) is typically reduced rather than oxidized when it goes from a higher oxidation state to a lower one, such as from MnO₄ (permanganate) to Mn²+ (manganese (II) ion).
As such, it is likely that in the given scenario, NH₄⁺ (ammonium) is the species being oxidized, as it would be the substance losing electrons (especially if it ends up as NO₃⁻ (nitrate) in the products).
It is important to look at the oxidation states of all the elements in both reactants and products to accurately determine which species is being oxidized and which is being reduced.
The reductant gets oxidized and the oxidant gets reduced in a redox reaction. Since ammonia (NH₄⁺) can lose electrons to form nitrate (NO₃⁻), it is reasonable to conclude that ammonia is the element being oxidized in this case.