When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of

(A) oxygen

(B) carbon dioxide

(C) nitrogen

(D) water vapour



  • Lime water [Ca(OH) 2 ] is a test for Carbon Dioxide [CO 2 ]. CO 2 turns lime water milky.
  • When we exhale,  carbon dioxide gas is expelled.
  • Upon reacting with lime water, calcium carbonate is formed.
  • Calcium carbonate is insoluble in water and turns it milky .

Test for CO2 - limewater turns milky-01.jpg

So, the correct answer is (b)

  1. Class 10
  2. Chapter 6 Class 10 - Life Processes (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo