Question

Which of the following order of radii is correct?

• A. $Li<Be<Mg$
• B. $N{a}^{+}>F^{-}>O^{-2}$
• C. $O<F<Ne$
• D. $H^{+}<L{i}^{+}<H^{-}$

Answer 1

The correct option is D $H^{+}<L{i}^{+}<H^{-}$

For $H$:
Cation is smaller than the parent atom while anion is bigger than the parent atom.

$H^{+}\text{and}L{i}^{+}$ are isoelectronic species.

So the $\text{Ionic Size}\propto \frac{1}{\text{Nuclear charge}}$

Hence the correct order is $H^{+}<L{i}^{+}<H^{-}$