Give reasons for the following:
$(a)$ Ions are more stable than atoms.
$(b)$ Noble gases show low reactivity.

(N/A) Ions are more stable than atoms because,except for the atoms of inert gases,the outermost shell of most atoms is incomplete. To achieve a stable electronic configuration (octet),atoms lose,gain,or share electrons to form ions.
$(b)$ The outermost shell of the atoms of noble gases is already complete (stable octet or duplet). Therefore,they have no tendency to lose,gain,or share electrons,resulting in low chemical reactivity.