Answer:
H₂(g) = oxidized
N₂(g) = reduced
Explanation:
Oxidized substances lose electrons and increase in oxidation number. Reduced substances gain electrons and decrease in oxidation number.
Lone elements always have an oxidation number of 0. So, N₂(g) and H₂(g) have oxidation numbers of 0.
Within compounds, hydrogen generally always have an oxidation of +1. Therefore, the hydrogen in NH₃(g) has an oxidation number of +1. In order to make the overall compound neutral, the nitrogen in NH₃(g) must have an oxidation number of -3 (to balance the +3 from the 3 hydrogens).
Since H₂(s) is losing electrons (goes from 0 to +1), it is being oxidized. Since N₂(g) is gaining electrons (goes from 0 to -3), it is being reduced.
