Q51 / 200 · NEET 2023 (Manipur) · Chemistry

Which one of the following represents all isoelectronic species?

  • A
    $\mathrm{Na}^{+}, \mathrm{Mg}^{2+}, \mathrm{O}^{-}, \mathrm{F}^{-}$
  • Correct answer
    B
    $\mathrm{Ca}^{2+}, \mathrm{Ar}, \mathrm{K}^{+}, \mathrm{Cl}^{-}$
  • C
    $\mathrm{Na}^{+}, \mathrm{Cl}^{-}, \mathrm{O}^{-}, \mathrm{NO}^{+}$
  • D
    $\mathrm{N}_2 \mathrm{O}, \mathrm{N}_2 \mathrm{O}_4, \mathrm{NO}^{+}, \mathrm{NO}$

Solution

(2) $\mathrm{Ca}^{2+}=20-2=18 \mathrm{e}^{-}$ $\begin{aligned} & \mathrm{Ar}=18 \mathrm{e}^{-} \\ & \mathrm{K}^{+}=19-1=18 \mathrm{e}^{-} \\ & \mathrm{Cl}^{-}=17+1=18 \mathrm{e}^{-}\end{aligned}$ So, $\mathrm{Ca}^{2+}, \mathrm{Ar}, \mathrm{K}^{+}$and $\mathrm{Cl}^{-}$are isoelectronic species.

Hence, the correct answer is option: 'B'.

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