In night the city roads and shops have a different types of light advertising.This different light is called neon gas lights.
But indeed this all lights are not just neon gas lights. In this light different other gases are included for example: Helium,Argon,krypton,xenon.
When electricity is passed on this gases every gas can produce different lights.Neon gas produce reddish orange light,Argon produce reddish blue light and helium produce white,yellow light (depends on voltage of electricity).Krypton produce yellow,green or dark yellow light and xenon produce blue or bluish green light.
Basically,electricity is passed on neon gas,this electricity in the form of energy, energy is separated the electrons from its atom then electron is again enter an atom because atom is unstable without electron entering of electron in an atom energy is released in the form of light.
All these gases are noble gases.All these gases are chemically unreactive.They not burn in usual conditions and not form chemical compounds.all these gases are diamagnetic in nature.all noble gases have complete outermost shell with the exception of helium.
All these gases are extract from air except helium.helium is extract from natural gass and these gases are combined with nitrogen,oxygen & carbon dioxide present in air.
For extraction of these noble gases air is cooled down when gases change into liquid and then boil it gases are expelled and collect it then passed electricity into it they produce light.