Question

1. when does a chemical reaction stop? when the excess reactant is used up. chemical reactions never stop. when the lab is finished. when the limiting reactant is used up.

Explanation:

In a chemical reaction, the limiting reactant determines the amount of product formed. Once it is completely consumed, there is no more substance to react further and the reaction stops, even if there is still excess reactant remaining.

Answer:

D. When the limiting reactant is used up.