Identify the reagent $R$ used in the reaction stated below.
$C_6H_5N_2Cl + R \rightarrow C_6H_6$

Consider the following four compounds $I, II, III,$ and $IV$.
Choose the correct statement$(s)$.
$(A)$ The order of basicity is $II > I > III > IV$.
$(B)$ The magnitude of $pK_b$ difference between $I$ and $II$ is more than that between $III$ and $IV$.
$(C)$ Resonance effect is more in $III$ than in $IV$.
$(D)$ Steric effect makes compound $IV$ more basic than $III$.

Phenyl isocyanide is prepared by which of the following reactions?

Reaction of nitrous acid with aliphatic primary amine in the cold gives

Which of the following is the strongest base?

Ethyl amine undergoes oxidation in the presence of $KMnO_4$ to form