Question

Which of the following alkali metal ions has lowest ionic mobility in aqueous solutions?

• A. $ Rb^{+} $
• B. $ Cs^{+} $
• C. $ Li^{+} $
• D. $ Na^{+}$

Answer 1

Answer: (C)

Smaller ions are hydrated to greater extent.
As a result they had largest size and least mobility.
$\because L i^{+}$is smallest cation among
$L i^{+}, N a^{+}, C s^{+}$and $R b^{+}$.
It is most extensively hydrated.
Has least mobility in aqueous solution.