Answer;
They are reactants
Explanation;
-In any chemical reactions there exists reactants and products; Reactants undergo chemical reaction to form products, they are chemical species which reacts. Reactants on the other hand are the species formed due to the reaction of reactants.
Therefore; in the reaction;
N2 + 3H2→ 2NH3
Nitrogen gas (N2) and (H2) are the reactants which reacts to form ammonia (NH3) gas which is the product.