Q54 / 200 · NEET 2007 · Chemistry

Identify the correct order of the size of the following:

  • Correct answer
    A
    $\mathrm{Ca}^{2+} < \mathrm{K}^{+} < \mathrm{Ar} < \mathrm{Cl}^{-} < \mathrm{S}^{2-}$
  • B
    $\mathrm{Ar} < \mathrm{Ca}^{2+} < \mathrm{K}^{+} \mathrm{Cl}^{-}< < \mathrm{S}^{2-}$
  • C
    $\mathrm{Ca}^{2+} < \mathrm{Ar} < \mathrm{K}^{+} < \mathrm{Cl}^{-} < \mathrm{S}^{2-}$
  • D
    $\mathrm{Ca}^{2+} < \mathrm{K}^{+} < \mathrm{Ar} < \mathrm{S}^{2-} < \mathrm{Cl}^{-}$

Solution

For isoelectronic species, size of anion increases as negative charge increases whereas size of cation decreases with increase in positive charge. Further ionic radii of anions is more than that of cations. $\mathrm{Ca}^{2+} < \mathrm{K}^{+} < \mathrm{Ar} < \mathrm{Cl}^{-} < \mathrm{S}^{2-}$

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

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