Final answer:
In aqueous solutions, H3O+ is the strongest acid and OH- is the strongest base that can exist in equilibrium with water.
Step-by-step explanation:
In aqueous solutions, H3O+ is the strongest acid and OH- is the strongest base that can exist in equilibrium with water. The reaction of a Brønsted-Lowry base with water results in the formation of a hydroxide ion. The leveling effect applies to solutions of strong bases, where any base stronger than OH- is leveled to the strength of OH- because it is the strongest base that can exist in equilibrium with water.