Multiple choice general knowledge science & technology

Exhaled air has what % of its oxygen left?

  1. 0%

  2. 77%

  3. 70%

  4. 25%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Exhaled air contains approximately 16-17% oxygen, which is about 77-80% of the 21% oxygen in inhaled air. This is because the lungs only extract about 4-5% of oxygen during breathing, leaving most of it unused. 0% is impossible since exhaled air still supports life, while 25% would imply more oxygen extraction than actually occurs.

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