Deep sea divers carry oxygen diluted by helium in cylinders instead of air. Give reasons.

Explanation

In deep sea the pressure is more than the normal tmospheric pressure. Solubility of a gas increases with the increase in pressure. Normal air contains 20% oxygen. Due to increase in solubility in deep sea, only 4% oxygen is required. If `N_(2)` is used to dilute `O_(2)`, it also dissolves in blood due to high pressure. When the diver comes up, the dissolved nitrogen escapes out in the form of bubbles which hinders the flow of blood. This causes painful sensation called E blend. The solubility of helium is the least among all the gases. Hence, He is used for diluting `O_(2)`.