Multiple choice

Which components of air are present in the air exhaled by humans during breathing?

  1. Only CO2

  2. More CO2 and less O2

  3. N2, CO2, O2 and water vapour

  4. CO2, O2 and water vapour
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Exhaled air contains all the components of inhaled air, but in different proportions: nitrogen remains the largest component, oxygen decreases (some used in respiration), carbon dioxide increases (produced by respiration), and water vapor is added. Therefore all four - N2, CO2, O2, and water vapour - are present.

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