Identify the most stable species in the following set of ions giving reasons
(a) `overset(+)(C)H_(3), overset(+)(C)H_(2) Br, overset(+)(C)HBr_(2), overset(+)(C)Br_(3)` (b) `overset(Θ)(C)H_(3), overset(Θ)(C)H_(2)Cl, overset(Θ)(C)HCl_(2), overset(Θ)(C)Cl_(3)`

Explanation

(i) `overset(o+)(C)H_(3)` ion the most stable : Replacement of H atoms in the carbocation with `Br` atoms increases the magnitude of positive charge on the carbocation due to its - I effect and thus, destabilizes the carbocation.
(ii) `overset(Θ)(C)Cl_(2)` is the most stable because the `Cl` atom has a strong - I effect. by replacing H atoms in the carbanion with `Cl` atoms the magnitude of negative charge on the carbon atom is reduced and the anion is stabilised.