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
B
Carbon dioxide
C
Nitrogen
D
Water vapour

Solution

The correct option is B Carbon dioxideHint - $$Ca(OH)_2$$ (lime water) gets converted into $$CaCO_3$$  (Calcium carbonate) by removal of water and addition of another gas.Part 1 - Definition: RespirationRespiration 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 - ConclusionFrom 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

0

Similar questions
View More

People also searched for
View More