Aug 26, 2022, 16:45 IST
Note: It helium is cooled to 2.2K at 1 – atmospheric pressure, it forms a new form of liquid called helium – II. The viscosity of this liquid is low. Unlike normal liquids, it flows upwards instead of flowing downwards.
Phyiscs Wallah Chemistry Doubts page consist of more questions for reference.
i) Mixed with helium it is used to protect electrical instruments from high voltages.
ii) Neon has a special property of giving an orange red colour in a discharge tube at 2mm of pressure. Hence, it is widely used in filling of glow lamps known as neon tubes for advertising purposes. It produces different colours when mixed with mercury vapour or with argon.
Table: Colours produced by noble gases
Gases filled in tube |
Colour of tube |
Visible colour |
1. Neon + argon + mercury |
Colourless |
Light blue |
2. Neon + argon + mercury |
Grey colour |
Dark blue |
3. Neon + argon + mercury |
Green colour |
Light green |
4. Neon + helium |
Colourless |
White |
5. Neon + helium |
Amber |
Golden yellow |
6. Neon |
Colourless |
Orange red |
7. Neon |
Light colour |
Dark red |
iii) Neon light is also used as signal lights and as becon lights for safe air navigation as the light possess fog, mist and storm – penetrating power.
iv) Neon lamps are also used in botanical gardens and the green houses as it stimulates growth and is effective in the formation of chlorophyll.