What percentage of atmospheric air is carbon dioxide?

  1. 0.04%
  2. 21%
  3. 4%
  4. 78%
Answer

A) 0.04%

Air is about 0.04% CO₂. O Level Biology · Topic 9 Human Gas Exchange · 9.1 Human gas exchange

Biology MCQ · More O Level Biology: Human Gas Exchange MCQs · Practise