$A$ major component of Borsch reagent is obtained by reacting hydrazine hydrate with which of the following?

Identify the products $A$ and $E$ in the following reaction sequence:

"The presence of an electron-withdrawing group $\left( -NO_2 \right)$ at the ortho and para positions in haloarenes increases the reactivity of haloarenes towards nucleophilic substitution reactions." Prove this with an example.

Why does the presence of a $-NO_2$ group at the $o,p$-positions increase the reactivity of haloarenes towards nucleophilic substitution reactions?

If $B$ is the major product,then identify $B$.

Chlorobenzene is: