Question -
Answer -
(i) Nitrates
Thermal stability
Nitrates of alkali metals, except LiNO3, decompose on strongheating to form nitrites.
LiNO3, on decomposition, givesoxide.
Similarto lithium nitrate, alkaline earth metal nitrates also decompose to giveoxides.
Aswe move down group 1 and group 2, the thermal stability of nitrate increases.
Solubility
Nitratesof both group 1 and group 2 metals are soluble in water.
(ii) Carbonates
Thermal stability
Thecarbonates of alkali metals are stable towards heat. However, carbonate oflithium, when heated, decomposes to form lithium oxide. The carbonates ofalkaline earth metals also decompose on heating to form oxide and carbondioxide.
Carbonates of alkali metals are soluble inwater with the exception of Li2CO3. Also, the solubilityincreases as we move down the group.
Carbonatesof alkaline earth metals are insoluble in water.
(iii) Sulphates
Thermal stability
Sulphatesof both group 1 and group 2 metals are stable towards heat.
Solubility
Sulphatesof alkali metals are soluble in water. However, sulphates of alkaline earthmetals show varied trends.
BeSO4 Fairly soluble
MgSO4 Soluble
CaSO4 Sparingly soluble
SrSO4 Insoluble
BaSO4 Insoluble
Inother words, while moving down the alkaline earth metals, the solubility oftheir sulphates decreases.