Among `N^(-3), O^(-2), F^(-), Na^(+), Mg^(+2) and Al^(+3)`
(b) Arrange them in the increasing ionic radii.

Explanation

Given ions are `N^(-3), O^(-2), F^(-), Na^(+), Mg^(+2) and Al^(+3)`
The increasing order of ionic radii among above ions is
`Al^(+3) lt Mg^(+2) lt Na^(+) lt F^(-) lt O^(-2) lt N^(-3)`
Reason: In case of iso electronic species as the nuclear charge increases ionic radii decreases.