Question

The inert gas which is substituted for nitrogen in the air, used by deep sea divers for breathing, is:
(A) Helium
(B) Argon
(C) Krypton
(D) Xenon

Answer 1

Helium is one of the inert gas, which is a very light gas and diffused very rapidly. At a low temperature, helium is a good conductor of heat and is less expensive. It is easy to store gas and it has low solubility in fluids even at high pressure.

Complete answer:
When the depth of the dive increases, the ambient pressure increases which result in increasing the diver’s exposure to breathing gases. Because of which it becomes increasingly narcotic, the deeper we move towards the bed of the sea.
To allow the gas mix to be breathed safely on deep dives, helium is added to the breathing mix for reduction of the proportions of nitrogen and oxygen below those of air. At depth, nitrogen present in the air is absorbed into the tissues and the blood. When we come up from the depth and the pressure reduces, thus Nitrogen expands forming the bubbles in the blood known as ‘the bends’. Helium is inert gas. It has smaller molecules than Nitrogen. It is a ‘smart gas’ as it is not used to break down inside the body so that it can provide energy.
On breathing the mixture of helium with oxygen at the depth, the pressure reduces at upwards, the helium escapes from the tissues of the body easily reducing the probability of forming bubbles and causing the bends. Thus nitrogen is required in low quantities which reduce nitrogen narcosis and other effects of the nitrogen gas at depth. The decrease of nitrogen causes a disease named bends.

Note:
When the sea divers dive deep in the sea, because of this there will be an increase in pressure and the large amount of nitrogen dissolves in their blood. Solubility of nitrogen decreases at the surface and separates from the blood and forms small air bubbles and thus, causing a disease named Decompression Sickness (DCS).