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Railways PYQCBT 1 2016

RRB NTPC · Question 74

In humans, exhaled air contains oxygen about ________.

  1. 40%

  2. 44%

  3. 16%

  4. 64%

Show answer & explanation

Answer: (C) 16%

Explanation

Inhaled air has about 21% oxygen. The body absorbs only part of it, so exhaled air still contains about 16% oxygen, along with about 4% carbon dioxide; this is why mouth-to-mouth resuscitation works.