Which of the following cannot be used for the preparation of $H_2$?

Hydrogen has higher ionization energy than alkali metals,due to its

Which of the following elements forms a covalent electron-deficient hydride?

Given below are two statements :
Statement-$I$: Methane and steam passed over a heated $Ni$ catalyst produces hydrogen gas.
Statement-$II$: Sodium nitrite reacts with $NH_4Cl$ to give $H_2O$,$N_2$ and $NaCl$.
In the light of the above statements,choose the most appropriate answer from the options given below :

Consider the following sequence of reactions: $Na + NH_{3(g)} \to [X]$ $\xrightarrow{N_2O} [Y]$ $\xrightarrow{\text{Heat}} [Z] (\text{Gas, Pure})$. Identify $[Z]$ gas.

Which is the poorest reducing agent?