All the $s$-block elements of the periodic table are placed in the groups...

Why does lithium show anomalous behavior?

$(a)$ Describe the chemical properties of alkali metals with air,water,dihydrogen,and halogens.
$(b)$ Explain the reduction potential of alkali metal elements.
$(c)$ Which type of solutions are formed on the reaction of alkali metals with liquid ammonia?

Which of the following metals is not found in the free state?

Which of the following elements does not exhibit variable valency?

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.