Which from the following amines has the highest $pK_{b}$ value?

The reduction of benzenediazonium chloride to phenylhydrazine can be accomplished by:

Identify $X$ and $Y$ in the following reactions:

$A$ compound of molecular weight $180$ is acetylated to give a compound of molecular weight $390$. The number of amino groups in the initial compound is:

Identify $X$ and $Y$ in the following reactions:
$Nitrobenzene \xrightarrow{Zn/NH_4Cl} X$
$Nitrobenzene \xrightarrow{Zn + KOH/C_2H_5OH} Y$

Aniline in a set of reactions yielded a product $D$. The structure of product $D$ would be:
Aniline $\xrightarrow{NaNO_2/HCl} A$ $\xrightarrow{CuCN} B$ $\xrightarrow{H_2/Ni} C$ $\xrightarrow{HNO_2} D$