Which of the following products is a Schiff base?
$C_2H_5NH_2 \xrightarrow{HNO_2} a$
$C_2H_5NH_2 \xrightarrow{C_6H_5CHO} b$
$C_2H_5NH_2 \xrightarrow{NOCl} c$
$C_2H_5NH_2 \xrightarrow{C_6H_5SO_2Cl} d$

Among the following,the weakest base is:

Aniline $\xrightarrow[{{0^{\circ}}C - {5^{\circ}}C}]{{NaNO_2/HCl}}A$ $\xrightarrow{{Ph-N(CH_3)_2}}B$
What is $B$?

Identify the product obtained when benzamide is treated with bromine and aqueous sodium hydroxide.

What is obtained when nitrobenzene is treated sequentially with $(i)$ $NH_4Cl / Zn$ dust and $(ii)$ $H_2SO_4 / Na_2Cr_2O_7$?

$A$ 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