MCQ
Consider the isoelectronic species, $ {Na}^{+}, {Mg}^{2+}, {F}^{-}$and ${O}^{2-}$. The correct order of increasing length of their radii is _____________.
  • A
    $\text{F}^{-}<\text{O}^{2-}<\text{mg}^{2+}<\text{Na}^{+}$
  • $\text{Mg}^{2+}<\text{Na}^{+}<\text{F}^{-}<\text{O}^{2-}$
  • C
    $\text{O}^{2-}<\text{F}^{-}<\text{Na}^{+}<\text{mg}^{2+}$
  • D
    $\text{O}^{2-}<\text{F}^{-}<\text{Mg}^{2+}<\text{Na}^{+}$

Answer

Correct option: B.
$\text{Mg}^{2+}<\text{Na}^{+}<\text{F}^{-}<\text{O}^{2-}$
Consider the isoelectronic species, $ {Na}^{+}, {Mg}^{2+}, {F}^{-}$and ${O}^{2-}$. The correct order of increasing length of their radii is $\text{Mg}^{2+}<\text{Na}^{+}<\text{F}^{-}<\text{O}^{2-}$ Explanation: Amongst isoelectronic ions, ionic radii decrease with increase in nuclear charge. $\text{Mg}^{2+}(12)<\text{Na}^{+}(11)<\text{F}{(10)}<\text{O}^{2-}(8)$

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