Give the uses of helium .

Explanation

1. Helium and oxygen mixture is used by divers in place of air oxygen mixture. This prevents the painful dangerous condition called bends.
2. Helium is used to provide inert atmosphere is electric arc welding of metals
3. Helium has lowest boiling point hence used in cryogenics (log temperature science).
4. It is much less denser than air the hence used for filling air balloons