Compound $A$ from the following reaction sequence is:

The major product of the reaction shown below is:

Aniline reacts with mixed acid (conc. $HNO_3$ and conc. $H_2SO_4$) at $288 \ K$ to give $P$ $(51 \%)$,$Q$ $(47 \%)$ and $R$ $(2 \%)$. The major product$(s)$ of the following reaction sequence is (are):
$R$ $\xrightarrow[2) Br_2, CH_3CO_2H]{1) Ac_2O, \text{pyridine}}$ $\xrightarrow{3) H_3O^+}$ $\xrightarrow{4) NaNO_2, HCl / 273-278 \ K}$ $\xrightarrow{5) EtOH, \Delta}$ $\xrightarrow{6) Sn/HCl}$ $\xrightarrow{7) Br_2/H_2O \text{ (excess)}} \text{Major Product}$

Which of the following has the highest value of $pK_b$?

Which among the following reactions represents the Carbylamine reaction?

In the following sequence $CH_3CH_2Cl$ $\xrightarrow{NaCN} (i)$ $\xrightarrow{Ni/H_2} (ii)$ $\xrightarrow{\text{acetic anhydride}} (iii)$,Product $(iii)$ is