General Knowledge - General Science - Discussion

Since Helium is a inert gas and makes no reaction.

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.

All given option exept helium having lower diffusion rate and hence can not be used.

Because nitrogen gas cause a disease called BENT which can also cause death. That's helium is used.

Helium is nontoxic & no adverse effect in veins.

Why Krypton or Xenon not use they are also inert gases ?

What is the chemical formula of krypton ?

But why inert gas is mixed with oxygen during deep sea diving?

Well, oxygen does not dissolve directly into blood under high pressure existing in the deep sea, hence inert gas like helium is mixed with oxygen during deep sea diving. I hope its clear.