Normal arterial pCO2 range is:

• A. 30–40 mmHg
• B. 35–45 mmHg
• C. 40–50 mmHg
• D. 45–55 mmHg

Answer: (B)

Normal arterial pCO2 reflects a balance between CO2 production and its removal by the lungs. In healthy adults, the arterial CO2 tension is about 40 mmHg, with a typical reference range of 35–45 mmHg. Values below 35 suggest hyperventilation, while values above 45 indicate hypoventilation. Among the given ranges, 35–45 mmHg matches this standard reference interval, whereas the other ranges extend too low or too high to be considered normal.