Question

Marcia is given an incomplete chemical equation that includes the number of nitrogen atoms present in the products of the reaction. How can she conclude that the reaction started with three nitrogen atoms?

Answer 1

If the products contain 3 nitrogen atoms, then so did the reactants since overall mass is conserved in a chemical reaction.

Answer 2

Sample response:

There would have to be three nitrogen atoms in the products. The law of conservation of matter states that the amount of substance before a reaction occurs should be the same as the amount of substance after the reaction.

hope this helps! Have a great one :D