Use of Noble Gases:-
Helium
(i)          Being non inflammable and very light, helium is extensively used in filling balloons and inflating airplane tyres.
(ii)         Helium- oxygen mixture is used by divers and in the treatment of asthama.
(iii)        Liquid belium is used to produce low temperatures.
(iv)       Being inert, helium is used in vacuum tubes, radio tubes, signal lamps etc.
Neon
(i)          Neon emits a characteristic orange-red glow when subjected to electric discharge at very low pressure. For the attractive glow and its visibility even in mists and fogs, neon lights are used for advertising signs and as beacon light for pilots.
Argon
(i)          In incandescent lamps, checks volatilization of tungsten filament and enhances the life of lamp.
(ii)         To provide inert atmosphere in welding and metallurgical processes.
(iii)        Argon is mainly used in incandescent, fluorescent and discharge lamps.
Krypton & Xenon
(i)          Krypton is better for filling tubes and valves than Ar but is very costly.
(ii)         Xenon is used in electrical flash bulbs for high speed photography.
Radon: - In radiotherapy of cancer.