Multiple choice

Consider the following statement about inhaled air and exhaled air:

  1. Exhaled air contains more carbon dioxide than inhaled air.
  2. Exhaled air is cooler than inhaled air.
  3. Inhaled air contains more moisture than exhaled air.
  4. Inhaled air contains more oxygen than exhaled air.
    Which of the above statements are correct?

  1. 1 & 2

  2. 2 & 3

  3. 3 & 4

  4. 1 & 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Inhaled air has about 21% oxygen and 0.04% carbon dioxide. During respiration, oxygen is absorbed and carbon dioxide is released, so exhaled air contains less oxygen (about 16%) and more carbon dioxide (about 4-5%). Exhaled air is warmer (body temperature) and more humid due to moisture from respiratory surfaces, not cooler or drier.

Keep practicing — related questions