A solution that contains an equal number of hydrogen (H+) and hydroxyl (OH-) ions is called a neutral solution.

Here's why:

* pH Scale: The pH scale measures the acidity or alkalinity of a solution.

* Hydrogen Ions: A high concentration of H+ ions indicates an acidic solution (low pH).

* Hydroxyl Ions: A high concentration of OH- ions indicates an alkaline (basic) solution (high pH).

* Neutral: In a neutral solution, the concentrations of H+ and OH- ions are equal, resulting in a pH of 7.

Examples of neutral solutions:

* Pure water

* Some saline solutions

Let me know if you have any other questions!