Neutral pH is 7.

Neutral pH is 7.

• A. 7
• B. 9
• C. 8
• D. 6

Answer: (A)

The key idea is how the pH scale defines acidity, neutrality, and basicity. Neutral pH means equal concentrations of hydrogen ions and hydroxide ions, and on the common 0–14 scale that point is 7. The scale is logarithmic, so each unit change represents a tenfold shift in hydrogen ion concentration; at pH 7 the H+ and OH− levels are both 1×10−7 M. Values below 7 are acidic (more H+), and values above 7 are basic/alkaline (more OH−). Therefore, 7 is the neutral point, making it the correct choice; 9 and 8 are basic, and 6 is acidic.

The key idea is how the pH scale defines acidity, neutrality, and basicity. Neutral pH means equal concentrations of hydrogen ions and hydroxide ions, and on the common 0–14 scale that point is 7. The scale is logarithmic, so each unit change represents a tenfold shift in hydrogen ion concentration; at pH 7 the H+ and OH− levels are both 1×10−7 M. Values below 7 are acidic (more H+), and values above 7 are basic/alkaline (more OH−). Therefore, 7 is the neutral point, making it the correct choice; 9 and 8 are basic, and 6 is acidic.