Which of the following sets have highest hydration enthalpy and highest ionic radiiNa and LiLi and RbK and NaCs and Na

The hydration enthalpy and ionic radii of an ion are dependent on the size of the ion.

1. Hydration enthalpy: It is the amount of energy released when one mole of gaseous ions combines with water to form hydrated ions. Smaller the size of the ion, greater is the hydration enthalpy. This is because smaller ions can get closer to the water molecules and form stronger bonds, releasing more energy. Therefore, among Na and Li, Li has the highest hydration enthalpy because it is smaller in size.

2. Ionic radii: It is the measure of the size of the ion. Larger the size of the ion, greater is the ionic radii. Therefore, among Li and Rb, Rb has the highest ionic radii because it is larger in size.

So, the set with the highest hydration enthalpy is Na and Li (with Li having the highest hydration enthalpy) and the set with the highest ionic radii is Li and Rb (with Rb having the highest ionic radii).