Compared to alkaline earth metals,what do alkali metals exhibit?

Sodium hydroxide is produced on a large scale:

When a small amount of sodium metal is dissolved in liquid ammonia at low temperature,which of the following does $NOT$ occur?

Which of the following is Indian saltpetre?

Identify the correct statements from the following :
$I$. Tendency to form halide hydrates gradually increases from $Be$ to $Ba$ down the group.
$II$. Tendency to form stable superoxides increases from $Li$ to $Cs$ down the group.
$III$. Low solubility of $LiF$ is due to its high lattice energy.
$IV$. Solubility of carbonates of group-$2$ elements increases down the group.

Sodium is heated in air at $300^{\circ} C$ to form $X$. $X$ absorbs $CO_2$ and forms $Na_2CO_3$ and $Y$. Which of the following is $Y$?