(a) Nitrates : Nitrates of alkali metals are of the type MNO3, they are soluble in water and do not undergo hydrolysis. Except LiNO3, other nitrates of this group decompose to nitrites and oxygen upon heating.
2MNO3 → 2MNO2+O2 ↑
Nitrates of alkaline earth metals are of the type M(NO3)2. They are soluble in water and upon heating they decompose into their corresponding oxides with evolution of a mixture of NO2 and oxygen.
2M(NO3)2

Δ

→

2MO + 4NO2+O2 ↑
(b) Carbonates : All alkali metals form carbonates of the type M2CO3. Their carbonates are highly stable towards heat and readily soluble in water. The stability and solubility of the carbonates increases in the same order:
Cs2CO3 > Rb2CO3 > K2CO3 > Na2CO3 > Li2CO3.
Li2CO3 decomposes on heating and is insoluble in water. Carbonates of alkaline earth metals (MCO3) are insoluble in water, they dissolve in water only in presence of CO2 due to the formation of a hydrogen carbonate.
MCO3+H2O+CO2 → M(HCO3)2
Solubility of carbonates decreases as we descend the group and stability increases due to increase in electropositive character of the metal.
(c) Sulphates : Alkali metal sulphates are of the type M2SO4. Except Li2SO4, all other sulphates are soluble in water. Alkaline earth metal sulphates are of the type MSO4. The solubility of sulphates decreases on moving down the group. CaSO4 is sparingly soluble, SrSO4,BaSO4 and RaSO4 are almost insoluble. The solubilities of BeSO4 and MgSO4 are due to high energy of solvation of smaller Be2+ and Mg2+ ions. The order of solubility is :
BaSO4 < SrSO4 < CaSO4 < MgSO4 < BeSO4.
The sulphates decompose on heating to give the corresponding oxide (MO).
2MSO4

Δ

→

2MO + 2SO2+O2.
The stability increases as the basic nature of the metal increases.
SrSO2 > CaSO4 > MgSO4 > BeSO4.