Question

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

• A. K+
• B. Rb+
• C. Li+
• D. Na+

Answer 1

Answer: (B)

Rb+

Answer 2

M+ + nH2O $\longrightarrow$ [ M (aq) ]+

hydrated cation

The extent of hydration depends upon the size of the ion, smaller the size of the ion, more highly it is hydrated and thus move slowly because of bigger size of hydrated ions. Hence with bigger atomic size the mobility of hydrated ion is highest and the order of the ionic mobility is, Li+ < Na+ < K+ < Rb+