In a reaction of aniline,a coloured product $C$ was obtained as shown below:
$A$ $\xrightarrow{NaNO_2/HCl} B$ $\xrightarrow{N,N-dimethylaniline, \text{cold}} C$
The structure of $C$ would be:

Arrange the following:
$(i)$ In decreasing order of the $pK_{b}$ values:
$C_{2}H_{5}NH_{2}, C_{6}H_{5}NHCH_{3}, (C_{2}H_{5})_{2}NH$ and $C_{6}H_{5}NH_{2}$
$(ii)$ In increasing order of basic strength:
$C_{6}H_{5}NH_{2}, C_{6}H_{5}N(CH_{3})_{2}, (C_{2}H_{5})_{2}NH$ and $CH_{3}NH_{2}$
$(iii)$ In increasing order of basic strength:
$(a)$ Aniline,$p-$nitroaniline and $p-$toluidine
$(b)$ $C_{6}H_{5}NH_{2}, C_{6}H_{5}NHCH_{3}, C_{6}H_{5}CH_{2}NH_{2}$
$(iv)$ In decreasing order of basic strength in gas phase:
$C_{2}H_{5}NH_{2}, (C_{2}H_{5})_{2}NH, (C_{2}H_{5})_{3}N$ and $NH_{3}$
$(v)$ In increasing order of boiling point:
$C_{2}H_{5}OH, (CH_{3})_{2}NH, C_{2}H_{5}NH_{2}$
$(vi)$ In increasing order of solubility in water:
$C_{6}H_{5}NH_{2}, (C_{2}H_{5})_{2}NH, C_{2}H_{5}NH_{2}$

In the hydrolysis of aniline,the reagent used is:

The most reactive amine towards dilute hydrochloric acid is ..........

Consider the following sequence of reactions. Assuming that the reaction proceeds to completion, then $137 \ mg$ of $4-$nitrotoluene will produce . . . . . . $mg$ of $B$. (Given molar mass in $g \ mol^{-1}: H = 1, C = 12, N = 14, O = 16, Br = 80$)

$X \ g$ of ethanamine was subjected to reaction with $NaNO_2 / HCl$ followed by hydrolysis to liberate $N_2$ and $HCl$. The $HCl$ generated was completely neutralized by $0.2 \ mol$ of $NaOH$. $X$ is . . . .