Q61 / 180 · AIIMS 2011 · Chemistry

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

  • Correct answer
    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.

Solution

A mixture of $2 \% \mathrm{O}_2$ and $98 \%$ He is used in diving apparatus which gives the same partial pressure of $\mathrm{O}_2$ as in normal air at $1 \mathrm{~atm}$. Due to high partial pressure and greater solubility, $\mathrm{N}_2$ gets dissolved in blood and form bubbles (bends or decompression sickness). Hence, $\mathrm{N}_2$ is replaced by helium which is much less soluble in biological fluids.

Hence, the correct answer is option: 'A'.

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