In which of the following groups all the three members are of the alkaline earth metals family?

$A$ compound $(A)$ is used in the preparation of washing soda to recover ammonia in the Solvay process. When $CO_2$ is bubbled through an aqueous solution of $(A)$,the solution turns milky. It is used in whitewashing due to its disinfectant nature. What is the chemical formula of $(A)$?

Match the compounds given in Column-$I$ with their uses mentioned in Column-$II$:

Column-$I$	Column-$II$
$A$. $CaCO_3$	$1$. Dentistry,ornamental work
$B$. $Ca(OH)_2$	$2$. Manufacture of sodium carbonate from caustic soda
$C$. $CaO$	$3$. Manufacture of high quality paper
$D$. $CaSO_4$	$4$. Used in white washing

The compounds of alkaline earth metals have the following magnetic nature:

Alloys of $......$ metal are light and strong and so are used in the manufacture of aeroplane parts.

Discuss the diagonal relationship between beryllium and aluminum metals.