Compare the solubility and thermal stability of the given compounds of the alkali metals with those of the alkaline earth metals.
Sulphates.

Explanation

Sulphates: (a) Except `Li_2SO_4`, the remaining sulphates of alkali metals are water soluble. The sulphates of alkaline earth metals are relatively less soluble in water than the corresponding sulphates of alkali metals. Further, their solubilities decrease down the group. (b) The sulphates of alkali metals are stable compounds and do not decompose on heating. On the other hand, alkaline earth metals dissociate on heating to give metal oxides and sulphur trioxide.
`MSO_4 overset(Delta) to MO + SO_3 uarr` (M = Be, Mg, Ca, Sr, Ba)
Thermal stability of the sulphates increases down the group. `Li_2SO_4` dissociate on heating just like `MgSO_4`.
`Li_2SO_4 overset(Delta)to Li_2O + SO_3 uarr`