Noble gases are considered as Inert because they are unreactive.
Explanation:
Seven noble elments are known to us , they are: helium, neon, argon, krypton, xenon, radon, and oganesson. Noble gases have 8 electrons in their outermost shell and hence their valence shell is complete, they donot need further electrons to complete their octet so they are unreactive. Also they posses following properties.
