What is the main difference between an acid and a base?

The main difference between an acid and a base lies in their behavior in terms of protons in solution. Acids are defined by their ability to donate protons (H⁺ ions) to other substances, which is a fundamental characteristic of acidic behavior. This is described by the Brønsted-Lowry theory of acids and bases. Conversely, bases have the capacity to accept protons. This proton transfer is central to many chemical reactions and helps to distinguish how acids and bases interact with each other.

For example, when hydrochloric acid (HCl) donates a proton, it transforms into its conjugate base (Cl⁻), while a base, such as ammonia (NH₃), can accept that proton to form its conjugate acid (NH₄⁺). This transfer of protons is essential for understanding acid-base chemistry and various chemical reactions in both organic and inorganic chemistry.

The other choices do not accurately portray the fundamental characteristics that define acids and bases. The notion that acids are always liquids and bases are solids is incorrect, as both can exist in various states. Additionally, the idea that acids taste sweet and bases salty is misleading, as many acids and bases can be hazardous and should not be tasted. Lastly,