Give the name 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 cheap compound having a high melting point used in a furnace is

The main constituent of enamel on the surface of teeth is:

$BaSO_4$ and carbon on heating react to produce:

The correct sequence of increasing melting points of $BeCl_2$,$MgCl_2$,$CaCl_2$,$SrCl_2$,and $BaCl_2$ is: