Which statement best describes a base in chemistry?

• A. Increases Hydrogen Ion Concentration
• B. Neutralizes Acids
• C. Reduces Hydrogen Ion Concentration
• D. Changes Color of Litmus Red

Answer: (C)

Bases reduce the concentration of hydrogen ions in a solution. In water, acids increase H+ (hydronium) ions, making the solution acidic. Bases counter that by either supplying hydroxide ions (OH−) or by accepting protons, so the free H+ ions drop. A classic outcome is that OH− helps form water with H+, lowering the hydrogen ion concentration and raising the pH. That direct effect is why describing a base as reducing hydrogen ion concentration is the best answer. While bases can neutralize acids in a reaction, and litmus tests show basic behavior (blue litmus), the essential characteristic being described here is the lowering of H+ in solution.