The reaction of zinc with an excess of aqueous alkali evolves hydrogen gas and gives:

Potassium nitrate is called

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.

When sodium metal is dissolved in liquid ammonia,a blue-coloured solution is formed. The blue colour is due to:

Among alkali metals,which element do you expect to be least electronegative and why?

Which of the following metals is the most reactive?