What does the Bronsted-Lowry theory define as a base?

The Bronsted-Lowry theory defines a base specifically as a substance that accepts protons (H+ ions) in a chemical reaction. This approach expands on the traditional definition of acids and bases by focusing on their role in proton transfer. According to this theory, an acid is a proton donor, while a base is a proton acceptor.

By this definition, when a base encounters an acid, it accepts protons, facilitating the chemical reaction by transforming into a conjugate acid. This is foundational to understanding acid-base chemistry, as it illustrates the dynamic nature of proton transfer in various reactions. This definition also allows for a more comprehensive understanding of acid-base behavior in diverse chemical environments, beyond just those that involve hydroxides or other traditional bases.

The other choices reflect different concepts or misunderstandings regarding acids and bases, which further underscores the unique clarity provided by the Bronsted-Lowry definition.