The ions O^ 2- , F^ - , Na^ + , Mg^ 2+ and Al^ 3+ are isoelectronic. Their ionic radii show:

Correct answer: B. a significant decrease from O^ 2- to Al^ 3+ Ionic radii decrease with the increase in charge on species.

NEET 2003

NEET 2003 · Chemistry · Structure of Atom

The ions O^ 2- , F^ - , Na^ + , Mg^ 2+ and Al^ 3+ are...

The ions

\mathrm{O}^{2-}, \mathrm{F}^{-}, \mathrm{Na}^{+}, \mathrm{Mg}^{2+}

and

\mathrm{Al}^{3+}

are isoelectronic. Their ionic radii show:

Aa significant increase from $\mathrm{O}^{2-}$ to $\mathrm{Al}^{3+}$
Ba significant decrease from $\mathrm{O}^{2-}$ to $\mathrm{Al}^{3+}$
Can increase from $\mathrm{O}^{2-}$ to $\mathrm{F}^{-}$ and then decrease from $\mathrm{Na}^{+}$ to $\mathrm{Al}^{3+}$
Da decrease from $\mathrm{O}^{2-}$ to $\mathrm{F}^{-}$ and then increase from $\mathrm{Na}^{+}$ to $\mathrm{Al}^{3+}$

B. a significant decrease from $\mathrm{O}^{2-}$ to $\mathrm{Al}^{3+}$

Ionic radii decrease with the increase in charge on species.