CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

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


A
Oxygen
loader
B
Carbon dioxide
loader
C
Nitrogen
loader
D
Water vapour
loader

Solution

The correct option is B Carbon dioxide
Hint - $$Ca(OH)_2$$ (lime water) gets converted into $$CaCO_3$$  (Calcium carbonate) by removal of water and addition of another gas.

Part 1 - Definition: Respiration
  • Respiration is the process by which a cell uses glucose in the presence of oxygen to produce energy in the form of ATP and carbon dioxide as a by-product.
  • This carbon dioxide ($$CO_2$$) is formed during the respiration process as a by-product is released during the exhalation of air from the lungs.

Part 2 - Experiment to show the production of $$CO_2$$ during respiration process.
  • The exhaled air has a high partial pressure of carbon dioxide gas.
  • When this exhaled air is blown into a test tube containing lime water ($$Ca(OH)_2$$), it converts the lime water into limestone ($$CaCO_3$$).
  • Chemical reaction: $$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$$ 

Part 3 - Conclusion
  • From the above discussion, we can conclude that exhaled air contains a high amount of carbon dioxide gas.
  • This high concentration of carbon dioxide converts the lime water $$Ca(OH)_2$$ into limestone ($$CaCO_3$$).

Final step - In the presence of carbon dioxide, the limewater turns milky.

Biology

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image