Which one on reaction with $NaOH$ solution gives inflammable gas?

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.

In the case of alkali metals,the covalent character decreases in the order

Which of the following properties is not true for an alkali metal?

Select the correct statement.

Which of the following metals produces hydrogen gas on reacting with cold dilute nitric acid?