Question

(a) What are inert elements ?

(b) Why do they exist as monoatoms in molecules ?

(c) What are valence electrons ?

Answer 1

(a) The elements present in the 18th group (VIII Group) are called inert gas. They ordinarily do not enter into any reaction.
(b) These exist as mono atoms because molecules of these elements contain only one atom.
(c)
Valency electrons: They have a complete outermost shell, (ns2 np6) = 8 electrons. so the valency electrons = 8 (except He, it has 2).