Which of the following is the strongest reducing agent?

Identify the correct statements from the following:
$A$) Among alkali metal ions,$Li^+$ has the highest hydration enthalpy.
$B$) The boiling point of alkali metals increases from $Li$ to $Cs$.
$C$) The density of $K$ is less than that of $Na$ and $Rb$.
$D$) $Li$ has a strong tendency to form superoxide.

Sodium metal can be stored under

The total number of elements among $S$,$P$,$Zn$,$Al$,$Sn$,$Pb$ which produce $H_2$ gas with $NaOH$ is

Which of the following statements is incorrect?

The oxide of an element whose electronic configuration is $1s^{2} 2s^{2} 2p^{6} 3s^{1}$ is