Uses of helium:
- Helium is not inflammable, and has a very low density. That is why it is used to fill weather balloons and airships. You know that helium has the lowest boiling point among all the elements in group eighteen. It has the lowest boiling point of any element, just 4.2 K. Hence, liquid helium is used as a cryogenic agent to perform experiments at very low temperatures.
- Liquid helium finds use in cryoscopy to obtain the very low temperatures required for superconductivity. Liquid helium is used to cool the superconducting magnets used in nuclear magnetic resonance spectrometers.
- It is used as the cooling gas in gas-cooled nuclear reactors, and as a flow gas in gas-liquid chromatography.
- Helium is used to dilute dioxygen in the cylinders carried by sea divers.
Uses of neon, argon, krypton and xenon:
- Neon is used in small amounts in discharge tubes and fluorescent bulbs that give the familiar red orange glow of "neon" signs.
- Argon is widely used to provide an inert atmosphere in laboratory apparatus, and for metallurgical processes, such as in welding stainless steel, aluminium and magnesium.
- Krypton is used in filament lamps and discharge tubes, while xenon is used in discharge tubes to produce the high-speed flash required for photography.
- Radon finds use in radiotherapy for the treatment of cancer.