What is the formula of lithium imide?

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.

How many of the following metals give oxides and nitrides when burnt in air?
$Be, Na, Mg, Ba, Sr, Li, K$

The alkali metals which form normal oxide,peroxide,as well as superoxides are:

Which is most basic in character?

What is the product formed when sodium is heated in a current of dry ammonia?