arrange the following alkali metal ions in decreasing order of their mobility:

Li+,Na+,K+,Rb+,Cs+

 

The given alkali metal ions can be arranged in order of their decreasing ionic mobilities in the following way.

Cs⁺ > Rb⁺ > K⁺ > Na⁺ > Li⁺

 

 

This can be explained as follows:

 

Li⁺ being smaller in size gets heavily hydrated than other alkali metals. The extent of hydration decreases from Li⁺ to Cs⁺. As a result, the ionic radii in water decrease in the following order:

Therefore, Li⁺ has the lowest mobility in water.

Hence, the ionic mobilities of aqueous solutions of alkali metal decreases in the following order:

Cs⁺ > Rb⁺ > K⁺ > Na⁺ > Li⁺

 

Hope, this answers your question.

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