Q82 / 200 · NEET 2012 (Screening) · Chemistry

The ease of adsorption of the hydrated alkali metal ions on an ion-exchange resins follows the order

  • A
    $\mathrm{Li}^{+} < \mathrm{K}^{+} < \mathrm{Na}^{+} < \mathrm{Rb}^{+}$
  • Correct answer
    B
    $\mathrm{Rb}^{+} < \mathrm{K}^{+} < \mathrm{Na}^{+} < \mathrm{Li}^{+}$
  • C
    $\mathrm{K}^{+} < \mathrm{Na}^{+} < \mathrm{Rb}^{+} < \mathrm{Li}^{+}$
  • D
    $\mathrm{Na}^{+} < \mathrm{Li}^{+} < \mathrm{K}^{+} < \mathrm{Rb}^{+}$

Solution

Ease of adsorption of the hydrated alkali metal ions on an ion-exchange resins decreases as the size of alkali metal ions increases. Since, the order of size of alkali metal ions $\mathrm{Li}^{+} < \mathrm{Na}^{+} < \mathrm{K}^{+} < \mathrm{Rb}^{+}$ Thus, the ease of adsorption follows the order $\mathrm{Rb}^{+} < \mathrm{K}^{+} < \mathrm{Na}^{+} < \mathrm{Li}^{+}$

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

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