Question

Assertion: Helium is used in diving apparatus.
Reason: Solubility of helium is less in blood.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (A)

A mixture of 2% $O_2$ and 98% He is used in diving apparatus which gives the same partial pressure of $O_2$ as in normal air at 1 atm. Due to high partial pressure and greater solubility, $N_2$ gets dissolved in blood and form bubbles (bends or decompression sickness). Hence, $N_2$ is replaced by helium which is much less soluble in biological fluids.