18)
In a chemical reaction, the is consumed completely during the reaction.
A) stoichiometry
B) excess reagent
C) ideal compound
D) limiting reactant

The answer is option D, limiting reactant.

Oftentimes in chemistry, there are leftovers of certain chemicals in reactions. When not all of a certain reactant is used up in a reaction, it is known as the excess reactant (since there is an excess of it). The reactant that's completely used up is known as the limiting reactant (since it limits the reaction from going any further)

-T.B.