Heating the acyl azide in dry toluene under reflux for $3$ hours gives a $90\%$ yield for a heterocyclic product. Identify the product $(A)$.

Which of the following chemicals are responsible for the production of methyl isocyanate,which caused the Bhopal gas tragedy?

Which of the following reactions does $NOT$ yield an amine?

$A$ trinitro compound,$1,3,5$-tris-($4$-nitrophenyl)benzene,on complete reaction with an excess of $Sn/HCl$ gives a major product,which on treatment with an excess of $NaNO_2/HCl$ at $0^{\circ} C$ provides $P$ as the product. $P$,upon treatment with excess of $H_2O$ at room temperature,gives the product $Q$. Bromination of $Q$ in aqueous medium furnishes the product $R$. The compound $P$ upon treatment with an excess of phenol under basic conditions gives the product $S$.
The molar mass difference between compounds $Q$ and $R$ is $474 \ g \ mol^{-1}$ and between compounds $P$ and $S$ is $172.5 \ g \ mol^{-1}$.
$(1)$ The number of heteroatoms present in one molecule of $R$ is . . . . .
[Use: Molar mass (in $g \ mol^{-1}$): $H=1, C=12, N=14, O=16, Br=80, Cl=35.5$
Atoms other than $C$ and $H$ are considered as heteroatoms]
$(2)$ The total number of carbon atoms and heteroatoms present in one molecule of $S$ . . . . . .
[Use: Molar mass in $g \ mol^{-1}$]: $H=1, C=12, N=14, O=16, Br=80, Cl=35.5$
Atoms other than $C$ and $H$ are considered as heteroatoms
Give the answer for question $(1)$ and $(2)$.

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

$A$ nitrile $X$ is treated with $LiAlH_{4}$ to obtain compound $Y$ $(C_{2}H_{7}N)$. In a separate reaction,$X$ is hydrolyzed in an acidic medium to obtain $Z$. The product obtained after mixing $Y$ and $Z$ will be: