Identify $(a)$ and $(b)$ in the following reaction:
$CH_3CH_2NH_2 + CHCl_3 + 3KOH \rightarrow (a) + (b) + 3H_2O$

The reaction of aniline with excess liquid bromine gives $......$.

Consider the above reaction,the product $A$ and product $B$ respectively are ...

$A$ hydrocarbon $A$ $(C_{4}H_{8})$ on reaction with $HCl$ gives a compound $B$ $(C_{4}H_{9}Cl)$ which on reaction with $1 \ mol$ of $NH_{3}$ gives compound $C$ $(C_{4}H_{11}N)$. On reacting with $NaNO_{2}$ and $HCl$ followed by treatment with water,compound $C$ yields an optically active compound $D$. The compound $D$ is

Azo-dyes are prepared from

The correct order of basic strength is: