Question

In an experiment to check the amount of carbon dioxide, atmospheric air and exhaled air is passed through lime water. If the rate of changing lime water milky in the tube containing exhaled air is 10. What is the approximate rate of changing lime water milky in the tube containing atmospheric air?
A. 30
B. 40
C. 5
D. Lime water doesn't turn milky in this tube

Answer 1

Hint:-Gaseous exchange takes place to ensure that respiration , digestion and removal of waste substances takes place. The best time for determination if carbon dioxide is to pass this gas through the solution of lime water. When limewater turns milky it detects the presence of carbon dioxide gas.

Complete answer:During gaseous exchange two processes usually occurs
Inhalation :-
The inhaled air contains more oxygen that is used to create energy and less carbon dioxide.
Exhalation:-
The exhaled air contains more carbon dioxide and is produced as a waste to be expelled out and less oxygen is produced.
During the gaseous exchange the exhalation and inhalation prevails as a result of diffusion and exchange through alveoli. Now let us see the presence of oxygen and carbon dioxide gas.

Gas	Oxygen
% in inhaled air of oxygen	21
% of oxygen in exhaled air	16

Gas	Carbon dioxide
% of $\mathop {CO}\nolimits_2 $ in inhaled air	0.04
%of $\mathop {CO}\nolimits_2 $ in exhaled air	4

Now let us calculate the rate of changing of lime water in tube
The air of the atmosphere contains 0.04% of carbon dioxide. The air we exhale contains 4% of carbon dioxide.
So, the air we exhaled has 100 times more concentrated.
The rate becomes $\dfrac{{10}}{{100}} = 0.5 = \dfrac{1}{2}$

So the rate of change of lime water will become half.

Note:- The concentration of carbon dioxide is more in exhaled air as it contains more waste from the body and throws it outside the body. The carbon Dioxide is eliminated so the blood gets purified and more oxygenated blood will remain inside the body .