The correct order of increasing ionic character among $LiH$,$NaH$,$KH$,$RbH$,$CsH$ is

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

Which of the following salts form hydrates? $CaCl_2$ $(I)$,$NaCl$ $(II)$,$LiCl$ $(III)$,$BaCl_2$ $(IV)$,$KCl$ $(V)$

The element with atomic number $55$ belongs to

Which of the following does not contain $Mg$:

The chemical formulas of $A$,$B$,and $C$ are:
$A + Na_2CO_3 \to B + C$
$A \xrightarrow{CO_2} \text{Milky cloud}, C$