Question

The ionic mobility of alkali metal ions in aqueous solution is maximum for:

• A. $K^{+}$
• B. $R{b}^{+}$
• C. $L{i}^{+}$
• D. $N{a}^{+}$

Answer 1

The correct option is B $R{b}^{+}$

As smaller the size of cation greater will be hydration of the metal cation.

In case of $K^{+},R{b}^{+},L{i}^{+},N{a}^{+}$

As $R{b}^{+}$ has larger size than other cations, so it will be less hydrated compared to others. So less number of $H_{2}O$ molecule will cover the $R{b}^{+}$ cation and more ease will be for movement of $R{b}^{+}$ cation in solution as compared to other cations.

Hence, ionic mobility of alkali metal ions in aqueous solution is maximum for $R{b}^{+}$.