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

The halides of alkaline earth metals form hydrates such as $MgCl_2 \cdot 6H_2O$,$CaCl_2 \cdot 6H_2O$,$BaCl_2 \cdot 2H_2O$,and $SrCl_2 \cdot 2H_2O$. What does this indicate about the halides of group $2$ elements?

The halides of alkaline earth metals form hydrates such as $MgCl_2 \cdot 6H_2O$,$CaCl_2 \cdot 6H_2O$,$BaCl_2 \cdot 2H_2O$,and $SrCl_2 \cdot 2H_2O$. This indicates that the halides of group $2$ elements are:

The correct order of density of $Be$,$Mg$,$Ca$,$Sr$ is

$BaSO_4$ and carbon on heating react to produce:

$CO_2$ is passed through lime water. Initially,the solution turns milky and then becomes clear upon continued bubbling of $CO_2$. The clear solution is due to the formation of: