The correct sequence of ionic mobility in aqueous solution of Rb+,k+,Cs+,Na+ is?

ionic mobility decrases with increase in atomic size

in alkali metal in aaqueos solution size order reverse

so order of ionic mobility order is

cs+ > rb+ >k+ >na+

The alkali metal ion exist as hydrated ions M+(H2O)n in the aqueous solution. The degree of hydration, decreases with ionic size as we go down the group. Hence Li+ ion is mostly hydrated e.g. [Li(H2O)6]+. Since the mobility of ions is inversely proportional to the size of the their hydrated ions, hence the increasing order of ionic mobility isLi+

Reverse order is ssen in case of alkali metals so begin with ce then rb then k then na and lastly li will be present due to reac5ivity