Correct order of mobility in fused state
Li+ > K+ > Na+ > Rb+
Li+ > Na+ > K+ > Rb+
Rb+ > K+ > Na+ > Li+
Rb+ > Na+ >K+ > Li+
In fused state, ionic size of Li+ < Na+ < K+ < Rb+ < Cs+ ∴mobility of Li+ > Na+ > K+ > Rb+ > Cs+ In aqueous solution : Hydration enthalpy α1size of ion