Question

molecules on an acid - base indicator react chemically with ions in a solution, causing the indicator to change color. which ions in the solution cause this reaction?
oxygen ions
water ions
hydrogen ions
nitrogen ions

Explanation:

Acid - base indicators change color based on the concentration of hydrogen ions ($H^+$) in a solution. They react with hydrogen ions to form different colored species. Oxygen, water, and nitrogen ions do not cause the color - change reaction in acid - base indicators.

Answer:

C. Hydrogen ions