To determine which solution Lila should identify as being a base, she would need to test the pH of each solution. Generally speaking:
- A solution with a pH less than 7 is considered an acid.
- A solution with a pH of exactly 7 is neutral (like pure water).
- A solution with a pH greater than 7 is considered a base.
If Lila tests the pH of the four solutions and finds one with a pH greater than 7, she should identify that solution as being a base. Examples of common bases include sodium hydroxide (NaOH) and ammonia (NH₃), which typically have pH values much greater than 7.