The solution of sodium metal in liquid ammonia is strongly reducing due to the presence of which of the following in the solution?

Metal $M +$ air $\xrightarrow{\Delta } A$ $\xrightarrow{H_2O} B$ $\xrightarrow{HCl}$ White fumes; Metal $M$ can be

Alkali metals .........

Which of the following is $CORRECT$ regarding alkali metals?
$I$. Pure $NaCl$ is hygroscopic
$II$. $(n - 1)d$ subshell is vacant only
$III$. Aqueous $NaHCO_3$ solution is more basic than $Na_2CO_3$ solution
$IV$. Both $Li^{+}$ and $Mg^{2+}$ do not form alums

Match the following:

Compound	Uses
$1$. Soda ash	$a$. In purification of sugar
$2$. Calcium oxide	$b$. As an antacid
$3$. Baking soda	$c$. In paper and textile industries
	$d$. To prepare pure fats and oils

Match the following metals with their oxidizing flame color.

Compound	Flame color
$1$. $Li$	$a$. Crimson red
$2$. $K$	$b$. Violet
$3$. $Cs$	$c$. Blue