What does acidity/pH indicate?

• A. The amount of dissolved oxygen.
• B. How acidic or basic water is; pH below 7 is acidic.
• C. The color of water.
• D. The temperature of water.

Answer: (B)

Acidity/pH tells you how acidic or basic water is, based on hydrogen ion activity. A pH below 7 means the water is acidic, pH 7 is neutral, and pH above 7 indicates basic (alkaline) conditions. The scale runs roughly 0 to 14, with each unit representing a tenfold change in hydrogen ion concentration. This matters because pH influences how metals in pipes may corrode, how taste and odor are perceived, and how effectively disinfectants like chlorine work. The other options describe different water quality attributes (dissolved oxygen, color, temperature) that aren’t determined by pH.