Question

Helium-oxygen mixture is used by deep sea divers in preference to nitrogen-oxygen mixture because

• A. helium is much less soluble in blood than nitrogen
• B. nitrogen is much less soluble in blood than helium
• C. due to high pressure deep under the sea nitrogen and oxygen react to give poisonous nitric oxide
• D. nitrogen is highly soluble in water

Answer 1

Answer: (A)

$He\text{-}{O}_2$ (80% : 20%) mixture is used by deep sea divers for artificial respiration. Because of low intermolecular forces in He, it is much less soluble in aqueous solutions (as compared to $N_2$ ) such as blood and does not cause caiseion sickness or bends by bubbling out of blood when the worker moves from high pressure (while in deep sea) to atmospheric pressure.