Which statement about pH is true?

Which statement about pH is true?

• A. pH measures the amount of dissolved oxygen in water.
• B. Acids have pH greater than 7.
• C. A solution with pH 7 is neutral.
• D. Bases have pH less than 7.

Answer: (C)

pH shows how acidic or basic a solution is by measuring hydrogen ion concentration. At room temperature, a neutral solution has equal amounts of H+ and OH−, giving pH 7. Lower pH means more H+ (acidic), higher pH means more OH− (basic). So a solution with pH 7 is neutral because [H+] = [OH−] and there is no overall excess of acidity or basicity. The other statements are not correct: pH does not measure dissolved oxygen, acids have pH less than 7, and bases have pH greater than 7.

pH shows how acidic or basic a solution is by measuring hydrogen ion concentration. At room temperature, a neutral solution has equal amounts of H+ and OH−, giving pH 7. Lower pH means more H+ (acidic), higher pH means more OH− (basic). So a solution with pH 7 is neutral because [H+] = [OH−] and there is no overall excess of acidity or basicity. The other statements are not correct: pH does not measure dissolved oxygen, acids have pH less than 7, and bases have pH greater than 7.