(a) Nitrates : Nitrates of alkali metals are of the type $\mathrm{MNO}_3$, they are soluble in water and do not undergo hydrolysis. Except $\mathrm{LiNO}_3$, other nitrates of this group decompose to nitrites and oxygen upon heating. $2\mathrm{MNO}_3$ → $2\mathrm{MNO}_2+\mathrm{O}_2$ ↑ Nitrates of alkaline earth metals are of the type $\mathrm{M}(\mathrm{NO}_3)_2$. They are soluble in water and upon heating they decompose into their corresponding oxides with evolution of a mixture of $\mathrm{NO}_2$ and oxygen. $2\mathrm{M}(\mathrm{NO}_3)_2$ $\xrightarrow[]{{\Delta}}$ 2MO + $4\mathrm{NO}_2+\mathrm{O}_2$ ↑ (b) Carbonates : All alkali metals form carbonates of the type $\mathrm{M}_2\mathrm{CO}_3$. Their carbonates are highly stable towards heat and readily soluble in water. The stability and solubility of the carbonates increases in the same order: $\mathrm{Cs}_2\mathrm{CO}_3$ > $\mathrm{Rb}_2\mathrm{CO}_3$ > $\mathrm{K}_2\mathrm{CO}_3$ > $\mathrm{Na}_2\mathrm{CO}_3$ > $\mathrm{Li}_2\mathrm{CO}_3$. $\mathrm{Li}_2\mathrm{CO}_3$ decomposes on heating and is insoluble in water. Carbonates of alkaline earth metals ($\mathrm{MCO}_3$) are insoluble in water, they dissolve in water only in presence of $\mathrm{CO}_2$ due to the formation of a hydrogen carbonate. $\mathrm{MCO}_3+\mathrm{H}_2\mathrm{O}+\mathrm{CO}_2$ → $\mathrm{M}(\mathrm{HCO}_3)_2$ 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 $\mathrm{M}_2\mathrm{SO}_4$. Except $\mathrm{Li}_2\mathrm{SO}_4$, all other sulphates are soluble in water. Alkaline earth metal sulphates are of the type $\mathrm{MSO}_4$. The solubility of sulphates decreases on moving down the group. $\mathrm{CaSO}_4$ is sparingly soluble, $\mathrm{SrSO}_4, \mathrm{BaSO}_4$ and $\mathrm{RaSO}_4$ are almost insoluble. The solubilities of $\mathrm{BeSO}_4$ and $\mathrm{MgSO}_4$ are due to high energy of solvation of smaller $\mathrm{Be}^{2+}$ and $\mathrm{Mg}^{2+}$ ions. The order of solubility is : $\mathrm{BaSO}_4$ < $\mathrm{SrSO}_4$ < $\mathrm{CaSO}_4$ < $\mathrm{MgSO}_4$ < $\mathrm{BeSO}_4$. The sulphates decompose on heating to give the corresponding oxide (MO). $2\mathrm{MSO}_4$ $\xrightarrow[]{{\Delta}}$ 2MO + $2\mathrm{SO}_2+\mathrm{O}_2$. The stability increases as the basic nature of the metal increases. $\mathrm{SrSO}_2$ > $\mathrm{CaSO}_4$ > $\mathrm{MgSO}_4$ > $\mathrm{BeSO}_4$.