Which among the following represents reagent $A$ in the given reaction?
$C_6H_5N_2^+Cl^- + A \xrightarrow{NaOH} \text{Product (Orange-red dye)}$

All but one of the following compounds react with aniline to give acetanilide. Which one does not?

In the reaction sequence $CH_3CH_2Br$ $\xrightarrow{AgCN} A$ $\xrightarrow{H_3O^+} HCOOH + B; B$ $\xrightarrow{CHCl_3/KOH} A$ $\xrightarrow{Reduction} C$,what are $A, B,$ and $C$ respectively?

$(i)$ Write structures of different isomeric amines corresponding to the molecular formula,$C_{4}H_{11}N$. $(ii)$ Write $IUPAC$ names of all the isomers. $(iii)$ What type of isomerism is exhibited by different pairs of amines?

$A$ hydrocarbon $'A'$ $(C_4H_8)$ on reaction with $HCl$ gives a compound $'B'$ $(C_4H_9Cl)$,which on reaction with $1 \ mol$ of $NH_3$ gives compound $'C'$ $(C_4H_{11}N)$. On reacting with $NaNO_2$ and $HCl$ followed by treatment with water,compound $'C'$ yields an optically active alcohol,$'D'$. Ozonolysis of $'A'$ gives $2 \ mols$ of acetaldehyde. Identify compounds $'A'$ to $'D'$. Explain the reactions involved.

The ammonolysis of alcohol is represented by the reaction $xCH_3OH + yNH_3 \xrightarrow[Al_2O_3/ThO_2]{300-400^{\circ}C} \text{Products}$. The products formed are: