Write structures of different isomers corresponding to the molecular formula $C_{3}H_{9}N$. Write $IUPAC$ names of the isomers which will liberate nitrogen gas on treatment with nitrous acid.

(A) The isomers for $C_{3}H_{9}N$ are:
$(a)$ $CH_{3}CH_{2}CH_{2}NH_{2}$: $\text{Propan-1-amine} (1^{\circ})$
$(b)$ $CH_{3}CH(NH_{2})CH_{3}$: $\text{Propan-2-amine} (1^{\circ})$
$(c)$ $CH_{3}NHCH_{2}CH_{3}$: $N\text{-methylethanamine} (2^{\circ})$
$(d)$ $CH_{3}N(CH_{3})_{2}$: $N,N\text{-dimethylmethanamine} (3^{\circ})$
Primary $(1^{\circ})$ aliphatic amines react with nitrous acid $(HNO_{2})$ to form unstable diazonium salts which decompose to evolve $N_{2}$ gas.
Therefore,$\text{Propan-1-amine}$ and $\text{Propan-2-amine}$ will liberate nitrogen gas.
$CH_{3}CH_{2}CH_{2}NH_{2} + HNO_{2} \to CH_{3}CH_{2}CH_{2}OH + N_{2} + H_{2}O$
$CH_{3}CH(NH_{2})CH_{3} + HNO_{2} \to CH_{3}CH(OH)CH_{3} + N_{2} + H_{2}O$