What is the normal value for arterial blood pH?

• A. 7.50
• B. 7.35-7.45
• C. 7.42
• D. 7.60

Answer: (C)

Arterial pH is a tightly controlled measure of how acidic or basic the blood is, reflecting the balance between acids and bases managed by buffers, respiration, and kidney function. In healthy people, the arterial pH sits within a narrow range of about 7.35 to 7.45. Values outside this window indicate acidemia or alkalemia and signal an imbalance in respiratory or metabolic processes. While the entire interval defines normality, a single representative normal value commonly used in practice is around 7.40, and 7.42 falls squarely within this normal range. By contrast, numbers like 7.50 or 7.60 would be considered alkalemic (above normal), showing that the pH is too high.