The pH scale ranges from which values?

• A. 0 to 14
• B. 1 to 14
• C. 7 to 14
• D. 0 to 10

Answer: (A)

pH is a logarithmic measure of hydrogen ion activity in water-based solutions, indicating acidity or basicity. The value 7 is neutral; values below 7 are acidic and values above 7 are basic (alkaline). The range most commonly used and taught for aqueous solutions is 0 to 14, covering from strong acids to strong bases. Because the scale is logarithmic, each unit change represents a tenfold change in hydrogen ion concentration, so moving from 5 to 4 makes the solution ten times more acidic. While extreme conditions can push pH slightly outside this range, 0–14 is the standard reference for typical contexts, which is why that option is the best choice.