Question

Argon,nion,helium etc are called what and why

Answer 1

They are called noble gases. This is so because they do not react with any compound or element. They have their outermost shell of electrons complete due to which they can't gain or lose electron and hence do not react.

Answer 2

these are called Noble gases or imagine gas. they are stable gases, there atoms are widely spread, we may be collected at high pressure.