Q3 / 160 · TS EAMCET 2022 (19 Jul Shift 2) · Chemistry

The correct order of ionic radii for the given species is

  • A
    $\mathrm{Na}^{+}>\mathrm{Al}^{3+}>\mathrm{Mg}^{2+}>\mathrm{K}^{+}$
  • Correct answer
    B
    $\mathrm{K}^{+}>\mathrm{Na}^{+}>\mathrm{Mg}^{2+}>\mathrm{Al}^{3+}$
  • C
    $\mathrm{K}^{+}>\mathrm{Na}^{+}>\mathrm{Al}^{3+}>\mathrm{Mg}^{2+}$
  • D
    $\mathrm{Al}^{3+}>\mathrm{Mg}^{2+}>\mathrm{K}^{+}>\mathrm{Na}^{+}$

Solution

Ionic radii of isoelectronic ions decreases with increase in the magnitude of nuclear charge. If the species is positively charged, then it has less ionic radii. Therefore; the correct order of ionic radii is $\mathrm{K}^{+}>\mathrm{Na}^{+}>$ $\mathrm{Mg}^{2+}>\mathrm{Al}^{3+}$

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

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