Which of the following bases contains which ion characteristic?

The correct answer is based on the nature of bases in chemistry. A base is defined as a substance that can accept protons (H+ ions) or donate electron pairs in a chemical reaction. One of the most common characteristics of bases is their ability to produce hydroxide ions (OH-) in solution.

The presence of hydroxide ions is a hallmark of basic substances. For example, when sodium hydroxide (NaOH) is dissolved in water, it dissociates to produce Na+ and OH- ions. The hydroxide ion is essentially the reason why a substance exhibits basic properties, such as a slippery feel and the ability to turn pH indicators like phenolphthalein pink.

In contrast, the other ions mentioned do not represent the defining characteristic of bases. The H+ ion is associated with acids, while Cl- and Na+ are typically associated with neutral compounds and do not directly contribute to the basicity of a solution. Thus, the identification of OH- as the ion that characterizes bases is fundamental to understanding acid-base chemistry.