Which type of substance releases OH⁻ ions in water?

The correct answer is based on the fundamental properties of acids, bases, and other types of substances in solution. When a substance is classified as a base, it has the ability to dissociate in water to produce hydroxide ions (OH⁻). This behavior is characteristic of bases, which are substances that can accept protons (H⁺) or donate pairs of valence electrons to form bonds.

In an aqueous environment, bases increase the concentration of OH⁻ ions, resulting in a basic (or alkaline) solution. Common examples of bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH), both of which dissociate in water to release OH⁻ ions.

Other classifications, like neutral solutions, acids, and organic compounds, do not exhibit this property. Neutral solutions maintain a balance of H⁺ and OH⁻ ions, resulting in a pH of approximately 7. Acids, on the other hand, release H⁺ ions in solution, which leads to a decrease in pH and does not contribute to the increase of OH⁻ ions. Organic compounds can have a diverse range of behaviors, but they do not typically have the property of releasing OH⁻ ions when dissolved in water.