Question 60: Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :
Assertion A : Helium is used to dilute oxygen in diving apparatus.
Reasons R : Helium has high solubility in \mathrm{O}_{2}.
In the light of the above statements, choose the correct answer from the options given below :
(1) \mathbf{A} is true but \mathbf{R} is false.
(2) \mathbf{A} is false but \mathbf{R} is true.
(3) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is the correct explanation of \mathbf{A}.
(4) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is NOT the correct explantion of \mathbf{A}.
Answer: Option (1)
Explanation:
Helium is used to dilute oxygen in diving apparatus because it is chemically inert
and has very low solubility in blood.
At high pressures under water, gases with higher solubility in blood can
cause decompression sickness due to bubble formation during ascent.
Helium has much lower solubility in blood compared to nitrogen,
so it reduces the risk of such effects and allows safe breathing at greater depths.
The reason given is incorrect because helium does not have high solubility
in \mathrm{O}_{2}; instead, its low solubility is the key factor.
Therefore, Assertion A is true, but Reason R is false.