Normal arterial pH range is:

• A. 7.30–7.40
• B. 7.35–7.45
• C. 7.45–7.55
• D. 7.50–7.60

Answer: (B)

Arterial pH is kept within a very narrow window because enzyme function and many cellular processes depend on a precise hydrogen ion concentration. The normal arterial pH is about 7.35 to 7.45, which is the range clinicians use as the reference for arterial blood. Values below this range indicate acidosis, while values above indicate alkalosis. Among the options, the 7.35–7.45 range matches the standard arterial reference, whereas 7.30–7.40 skews toward acidosis, and the higher ranges exceed what is normally seen in arterial blood. The body maintains this balance through buffering, plus rapid respiratory regulation of CO2 and renal regulation of bicarbonate.