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

the answer will be c

Answer 2

At first nitrogen was used but since it dissolves in the blood when the pressure is high and becomes toxic, so helium is used as it does not dissolve in the blood and is non toxic.

Helium is the substitute for Nitrogen in the deep sea divers their oxygen cylinders contains oxygen with Helium when they were using Nitrogen in the cylinders they found that the divers when they come to the land because of difference in pressure theirs veins get bursted and they used to get bends in their legs and hands.With helium it is not observed as the rate of diffusion of He is greater than nitrogen along with it's non poisonous nature make it suitable to use.

so your answer is option no a ; helium is much less soluble in blood than nitrogen