Give a comparison of properties between lithium and other alkali metals.

(N/A) $i$. Lithium is much harder. Its $m.p.$ and $b.p.$ are higher than the other alkali metals.
$ii$. Lithium is the least reactive but the strongest reducing agent among all the alkali metals. On combustion in air,it forms mainly monoxide,$Li_2O$,and the nitride,$Li_3N$,unlike other alkali metals.
$iii$. $LiCl$ is deliquescent and crystallises as a hydrate,$(LiCl \cdot 2H_2O)$,whereas other alkali metal chlorides do not form hydrates.
$iv$. Lithium hydrogen carbonate is not obtained in the solid form,while all other elements form solid hydrogen carbonates.
$v$. Lithium,unlike other alkali metals,forms no ethynide on reaction with ethyne.
$vi$. Lithium nitrate when heated gives lithium oxide $(Li_2O)$,whereas other alkali metal nitrates decompose to give the corresponding nitrite.
$4LiNO_3 \rightarrow 2Li_2O + 4NO_2 + O_2$
$2NaNO_3 \rightarrow 2NaNO_2 + O_2$
$vii$. $LiF$ and $Li_2O$ are comparatively much less soluble in water than the corresponding compounds of other alkali metals.