Which of the alkaline earth metals cation has least hydration enthalpy ?

Be2+ > Mg2+ > Ca2+ > Sr2+ > Ba2+  : Size of isolated M+2  ionsBe2+ > Mg2+ > Ca2+ > Sr2+ > Ba2+ : Degree of hydrationBe2+ > Mg2+ > Ca2+ > Sr2+ > Ba2+ : Hydration EnthalpiesAs the size of M+2 ions [isolated] increases effective nuclear charge on the ion decreases nuclear attractive forces on the water molecules decreases, number of water molecules surrounded around the M+2 ion decreases degree of hydration decreases hydration enthalpy decreases