Activity – To show that exhaled air has carbon dioxide
i) Take some freshly prepared lime water in a test tube.
ii) Blow air through this lime water.
iii) Note how long it takes for the lime water to turn milky.
iv) Use a syringe or pichkari to pass air through some fresh lime water taken in another test tube (Fig.).
v) Note how long it takes for this lime water to turn milky.
vi ) What does this tell us about the amount of carbon dioxide in the air that we breathe out?