Explain Activity 6.4 NCERT class 10 science Life processes

 

Activity 6.4 NCERT class 10 science chapter 6 Life processes

Brief procedure: Activity 6.4 asks us to blow air from the mouth into a solution of lime water and compare the result with air blown using syringe or pichkari.

Observation:

When we blow Air through mouth it turns lime water milky instantaneously. While when we blow air through syringe or pichkari, it takes a lot of time and effort to turn the lime water milky.

Explanation: 

Our body cells produce carbon dioxide through oxidation of food. This gas is exhaled outside through the lungs. Lime water reacts with CO₂ to form an insoluble precipitate. This turns lime water milky.

Ca(OH)₂(aq)       +     CO₂(g)   ——–> CaCO₃(s)

(Lime)                                             (Insoluble Precipitate)

When syringe or pichkari is used, atmospheric air is pushed through the lime water. Atmospheric air contains very less amount of CO₂. As a result lime water do not turn milky or takes a lot of effort.

Inference:

This experiment demonstrates that our lung exhales carbon dioxide..

For more details, you can visit the related article from Education.com.

Next: Experiment to demonstrate yeast produces carbon dioxide. Activity 6.5.

See also: Experiment to see the effect of saliva on starch: Activity 6.3.