Limewater turns milky faster when you breathe out through it because expired air contains

  1. more nitrogen
  2. less water
  3. more carbon dioxide
  4. more oxygen
Answer

C) more carbon dioxide

CO₂ turns limewater milky. O Level Biology · Topic 9 Human Gas Exchange · 9.1 Human gas exchange

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