Consider the following statements. I. $\mathrm{Cs}^{+}$ion is more highly hydrated than other alkali metal…
Consider the following statements.
I. $\mathrm{Cs}^{+}$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 $\mathrm{Li}, \mathrm{Na}, \mathrm{K}, \mathrm{Rb}$, the metal, $\mathrm{Rb}$ has the highest melting point.
IV. Among the alkali metals $\mathrm{Li}, \mathrm{Na}, \mathrm{K}, \mathrm{Rb}$, only $\mathrm{Li}$ forms peroxide when heated with oxygen.
Select the correct statement is.
$I$
$II$
$III$
$IV$
Solution
Li is the only alkali metal which reacts directly with $\mathrm{N}_2$ to give nitride $\left(\mathrm{Li}_3 \mathrm{~N}\right)$
$6 \mathrm{Li}+\mathrm{N}_2 \rightarrow 2 \mathrm{Li}_3 \mathrm{~N}$