Question

For $N{a}^{+},M{g}^{2+},F^{-}$ and $O^{2-}$ the correct order of increasing ionic radii is :

• A. $O^{2-}<F^{-}<N{a}^{+}<M{g}^{2+}$
• B. $M{g}^{2+}<N{a}^{+}<F^{-}<O^{2-}$
• C. $M{g}^{2+}<O^{2-}<N{a}^{+}<F^{-}$
• D. $N{a}^{+}<M{g}^{2+}<F^{-}<O^{2-}$

Answer 1

The correct option is B $M{g}^{2+}<N{a}^{+}<F^{-}<O^{2-}$

All the species are iso-electronic $\left(10e^{-}\right)$

For iso-electronic species more the positive change, smaller the ionic radii.

For iso-electronic species more negative change, bigger the ionic radii

Hence the order is $M{g}^{2+}<N{a}^{+}<F^{-}<O^{2-}$

Hence, the correct option is B.