What are noble gases ?

Why are zero group elements called noble gases or inert gases?

The source of most of the noble gases is:

(A): Electron gain enthalpy of noble gases is very less (R): Atoms of noble gases have completely filled orbitals

Which is not true about noble gases ?

The ease of liquification of noble gases M decreases in the order

The heats of vaporization of noble gases vary in the order

Which statement about noble gases is not correct ?

The correct order of enthalpy of vaporsation of noble gases is