Answer :
An acid is typically defined by its chemical behavior and properties in a solution. The most common definitions used are:
1. Arrhenius Definition: An acid is a substance that increases the concentration of hydrogen ions (H+) when dissolved in water. This results in a solution with a pH less than 7.
2. Brønsted-Lowry Definition: An acid is a substance that can donate a proton (H+) to another substance. This definition expands the concept of acids beyond those substances that can dissolve in water.
3. Lewis Definition: A Lewis acid is defined as an electron pair acceptor. This broader definition encompasses more substances as acids, including those that don't necessarily donate hydrogen ions.
These definitions help classify and understand various substances' behavior in different chemical contexts.
