Explain the conversion of aniline to p-toluidine.

Identify $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$ in the following reactions.

${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{N}}_2\mathrm{Cl} \underset{\mathrm{HCN}}{\overset{\mathrm{CuCN}}{\to }} \mathrm{A} \stackrel{{\mathrm{H}}_2\mathrm{O}/{\mathrm{H}}^{+}}{\to } \mathrm{B}$

Identify $\mathrm{A}$ and $\mathrm{B}$ in the following reaction.

${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{N}}_2\mathrm{Cl}\underset{∆}{\overset{\mathrm{HOH}}{\to }} \mathrm{A}\stackrel{{\mathrm{Br}}_2}{\to } \mathrm{B}$

Identify the reagent used in the following conversion:

${\mathrm{C}}_6{\mathrm{H}}_5{\stackrel{+}{\mathrm{N}}}_2\stackrel{-}{\mathrm{Cl}}\stackrel{ ? }{\to }{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CN}+{\mathrm{N}}_2$

Identify the compounds $\mathrm{A}$ and $\mathrm{C}$ in the following reaction:

$\left(\mathrm{A}\right)\underset{273 \mathrm{K}}{\overset{ {\mathrm{NaNO}}_2+\mathrm{HCl} }{\to }}\underset{\left(\mathrm{B}\right)}{{\mathrm{C}}_6{\mathrm{H}}_5{\stackrel{+}{\mathrm{N}}}_2\stackrel{-}{\mathrm{Cl}}}\stackrel{ \mathrm{Cu}/\mathrm{HBr} }{\to }\left(\mathrm{C}\right)+{\mathrm{N}}_2+\mathrm{CuCl}$

Identify $\left[\mathrm{A}\right]$ and $\left[\mathrm{B}\right]$ in the following chemical reactions.

${\mathrm{C}}_6{\mathrm{H}}_5{{\mathrm{N}}_2}^{+}{\mathrm{Cl}}^{-}\underset{{\mathrm{NaNO}}_2}{\overset{\mathrm{Cu}}{\to }}\left[\mathrm{A}\right]\underset{6\left[\mathrm{H}\right]}{\overset{\mathrm{Sn}/\mathrm{HCl}}{\to }}\left[\mathrm{B}\right]$

Which of the following reactions is used to prepare aryl fluorides from diazonium salts and fluoroboric acid?

Identify $\mathrm{A}$ and $\mathrm{B}$ in the following reaction:

${\mathrm{C}}_6{\mathrm{H}}_5{\stackrel{+}{\mathrm{N}}}_2\stackrel{-}{\mathrm{Cl}}\underset{△}{\overset{ {\mathrm{H}}_2\mathrm{O} }{\to }}\mathrm{A}\underset{{\mathrm{H}}_2\mathrm{O}}{\overset{ {\mathrm{Br}}_2 }{\to }}\mathrm{B}$