Sodium hydroxide (a base) reacts with hydrochloric acid. After the reaction is complete, a pH indicator is added to the solution. The solution turns blue, indicating that the solution is basic. What is the limiting reactant?

hydrochloric acid

Explanation:

The hydrochloric acid in this reaction is the limiting reactant. A limiting reactant is the reactant that is used up in a chemical reaction. It determines the extent of the reaction.

Since the solution indicates a basic one after the end of the reaction, this suggests that more of the sodium hydroxide is still left unreacted with.

The reactant in excess supply here is the sodium hydroxide and the bulk of it is till left in solution.