Which of the following represents a strong base?

A strong base is a substance that can completely dissociate in solution to produce a high concentration of hydroxide ions (OH-). The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, indicating a balance between hydrogen ions (H+) and hydroxide ions.

In the context of pH values, a pH of 14 represents a very basic (alkaline) solution, which means it has a much higher concentration of hydroxide ions compared to hydrogen ions. This high pH corresponds to substances like sodium hydroxide or potassium hydroxide, which are common strong bases and are capable of significantly increasing the alkalinity of a solution.

On the other hand, a pH of 0 indicates a very strong acid, while a pH of 7 indicates neutrality and does not represent either an acidic or a basic condition. A pH of 5 indicates a weakly acidic solution. Thus, among the choices given, the pH of 14 is the only one that clearly indicates a strong base.