What measure reflects how acidic or basic an aqueous solution is?

• A. A measure of temperature stability.
• B. The concentration of solute in a solvent.
• C. A measure of the amount of solvent in a solution.
• D. A measure of how acidic or basic an aqueous solution is; Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic or alkaline.

Answer: (D)

pH is the measure of how acidic or basic an aqueous solution is. It ties directly to hydrogen ion concentration—the more hydrogen ions present, the more acidic the solution and the lower the pH; fewer hydrogen ions (or more hydroxide ions) raise the pH and make the solution basic. On the usual scale at room temperature, 7 is neutral; values below 7 indicate acidity and values above 7 indicate basicity or alkalinity. This description precisely captures what pH measures. Options describing temperature stability, solute concentration, or the amount of solvent don’t tell you how acidic or basic the solution is.