The final product formed when Methyl amine is treated with${\mathrm{NaNO}}_2$ and $\mathrm{HCl}$ is:

Aliphate amines on reacting with ${\mathrm{NaNO}}_2$ and $\mathrm{HCl}$produces an alcohol.

Methylamine produces ${\mathrm{CH}}_3^{+}$ when it combines with ${\mathrm{NaNO}}_2$, and it produces methylalcohol when it mixes with water.

${\mathrm{CH}}_3{\mathrm{NH}}_2+{\mathrm{NaNO}}_2+\mathrm{HCl}\to {\mathrm{CH}}_3\mathrm{OH}+{\mathrm{N}}_2+\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}$