The ion which has the lowest ionic mobility is

Options

A. `Rb^+`
B. `K^(+)`
C. `Na^(+)`
D. `Li^(+)`

Answer

D

Explanation

`Li` ion has the lowest ionic mobility due to the extensive hydration of ion as a result of very high charge density on account of its very small size.
The higher charger density causes `Li` ions to be more highly hydrated by ion-diode interactions than the larger ions. Since a hydrated ion has to drag along a shell of water as it moves through the solution, its mobility in naturally less than that of an unhydrated ion.