Question

is the process of using no₃⁻ to make n₂ a reduction or an oxidation reaction?
reduction
oxidation

Explanation:

Reduction is a gain of electrons or a decrease in oxidation state. In the conversion of $NO_3^-$ to $N_2$, the nitrogen in $NO_3^-$ has an oxidation state of +5 and in $N_2$ it has an oxidation state of 0. There is a decrease in oxidation state, which indicates a gain of electrons. So it is a reduction reaction.

Answer:

Reduction