What is the normal respiratory rate for an adult?

• A. 12-20/min
• B. 8-12/min
• C. 20-30/min
• D. 30-40/min

Answer: (A)

The main idea is knowing the normal resting breathing rate for a healthy adult. At rest, most adults breathe about 12 to 20 times per minute. This range reflects the balance between the body’s metabolic needs and the ventilation the lungs provide, under the control of the brainstem and chemical sensors that respond to carbon dioxide, oxygen, and pH levels.

Breathing slower than this range can indicate hypoventilation or suppression of the respiratory drive, while breathing faster can occur with fever, anxiety, pain, infection, or respiratory illness. The other options are outside the usual resting range: 8-12 is at the low end or below normal, and 20-30 or 30-40 show tachypnea, often signaling increased demand or distress.