Ionic mobility of which of the following alkali metal ions is lowest when aqueous solution of their salts are put under an electric field ?

Options

A. `K`
B. `Rb`
C. `Li`
D. `Na`

Answer

C

Explanation

Ionic mobility `prop (1)/("size of hydrated ion")`
Smallar size hydrated ion in aq. Solution `-Rb^(+)(aq)`
Larger size hydrated ion in aq. Solution `-Li^(+)(aq)`
Lowes ionic mobility in aq. Solution `rarr Li^(+)(aq)` due to high hydration.