A substance with an equal number of hydrogen ions (H+) and hydroxide ions (OH-) is considered neutral. This means it has a pH of 7.

Here are some examples:

* Pure water: While water can ionize slightly, the concentration of H+ and OH- ions is equal, making it neutral.

* Salt solutions: Many salts, when dissolved in water, do not significantly alter the balance of H+ and OH- ions, resulting in a neutral solution.

It's important to note that a solution can become acidic or basic if there is an imbalance between H+ and OH- ions.