why does Li+  ions has the largest size in aqueous solution?

 Li⁺  have larger size in aq. solution due to the presence of the water molecules present inside the solution surrounds easily and become the solution to be more hydrated compairing to the corresponding elements present in the aq. solution.

As Li+ has smallest size so extent of hydration is highest& easily hydrated by more water molecules. So size is maximum.

Is sunflower a flower?

It has largest size in aqueous solution due to its greater hydration enthalpy . It decrease down the group. So lithium ion surrounds by greater water molecules due to its small size and hydration enthalpy