Sodium gives blue colour with $NH_3$ solution,this blue colour is due to

The reactivity of sodium metal with water is utilized in which of the following processes?

Which of the following is not hygroscopic?

The elements of group $IA$ provide a colour to the flame of a Bunsen burner due to

Consider the following statements.
$I$. $Cs^{+}$ ion is more highly hydrated than other alkali metal ions.
$II$. Among the alkali metals,only lithium forms a stable nitride by direct combination with nitrogen.
$III$. Among the alkali metals $Li, Na, K, Rb$,the metal $Rb$ has the highest melting point.
$IV$. Among the alkali metals $Li, Na, K, Rb$,only $Li$ forms peroxide when heated with oxygen.
Select the correct statement.

$NO_2$ is not obtained on heating: