Among the sulphates of alkaline earth metals,the solubilities of $BeSO_4$ and $MgSO_4$ in water,respectively,are

Give a brief explanation of the carbonate,sulphate,and nitrate compounds of alkaline earth metal elements.

Give two uses of beryllium and magnesium.

$s-$block element which cannot be qualitatively confirmed by the flame test is ..... .

Give two uses of Plaster of Paris.

How would you explain the following observations?
$(i)$ $BeO$ is almost insoluble but $BeSO_4$ is soluble in water,
$(ii)$ $BaO$ is soluble but $BaSO_4$ is insoluble in water,
$(iii)$ $LiI$ is more soluble than $KI$ in ethanol.