Compare the solubility and thermal stability of the following compounds of the alkali metals with those of the alkaline earth metals: $(i)$ Nitrates,$(ii)$ Carbonates,$(iii)$ Sulphates.

(N/A) $(i)$ Nitrates:
Thermal stability: Alkali metal nitrates,except $LiNO_3$,decompose on strong heating to form nitrites $(2MNO_3 \longrightarrow 2MNO_2 + O_2)$. $LiNO_3$ and all alkaline earth metal nitrates decompose to form oxides $(2M(NO_3)_2 \longrightarrow 2MO + 4NO_2 + O_2)$. Thermal stability increases down both groups.
Solubility: Nitrates of both group $1$ and group $2$ metals are generally soluble in water.
$(ii)$ Carbonates:
Thermal stability: Alkali metal carbonates (except $Li_2CO_3$) are stable towards heat. $Li_2CO_3$ and all alkaline earth metal carbonates decompose on heating to form oxides and $CO_2$ $(MCO_3 \longrightarrow MO + CO_2)$.
Solubility: Alkali metal carbonates are soluble in water (except $Li_2CO_3$),and solubility increases down the group. Alkaline earth metal carbonates are generally insoluble in water.
$(iii)$ Sulphates:
Thermal stability: Sulphates of both group $1$ and group $2$ metals are generally stable towards heat.
Solubility: Alkali metal sulphates are soluble in water. For alkaline earth metals,solubility decreases down the group $(BeSO_4 > MgSO_4 > CaSO_4 > SrSO_4 > BaSO_4)$.