Which one of the following methods is most suitable for preparing deionized water?

Li⁺ has the highest hydration enthalpy.

Hence it is most hydrated

Therefore, Correct order of hydrated radii is Cs⁺ < Rb⁺ < K⁺ < Na⁺ < Li⁺

Sodium carbonate is a white crystalline solid which exists as a decahydrate,  This is also called washing soda.

Suspension of slaked lime in water is known as milk of lime

Crude sodium chloride obtained by crystallisation of brine solution contains CaSO₄, Na₂SO₄ and MgCl₂

Beryllium salts are easily hydrolysed

Gypsum : CaSO₄ * 2H₂O