Unknown salt + $\mathrm{Al}$-powder + $\mathrm{NaOH}$(conc.) $\to$

Gas comes out which turns Nessler's reagent brown. The salt may be :

Gas comes out which turns Nessler's reagent brown. The salt may be :

${\mathrm{K}}_2{\mathrm{HgI}}_4+{\mathrm{NH}}_3⟶\underset{\mathrm{Brown} \mathrm{ppt}.}{\mathrm{HgO}\cdot {\mathrm{Hg}}_{\searrow \mathrm{I}}^{\nearrow {\mathrm{NH}}_2}}+{\mathrm{I}}^{-}+{\mathrm{H}}_2\mathrm{O}$

${\mathrm{NaNO}}_2+\mathrm{Al}+\mathrm{NaOH}\to {\mathrm{NaAl}}_2+{\mathrm{NH}}_3\uparrow$

${\mathrm{NaNO}}_3+\mathrm{Al}+\mathrm{NaOH}\to {\mathrm{NaAlO}}_2+{\mathrm{NH}}_3\uparrow$

$N{H}_4\mathrm{Cl}+\mathrm{NaOH}⟶{\mathrm{NH}}_3+\mathrm{NaCl}+{\mathrm{H}}_2\mathrm{O}$

${\mathrm{NH}}_4{\mathrm{HCO}}_3+\mathrm{NaOH}⟶{\mathrm{NH}}_3+{\mathrm{N}}_2\mathrm{O}+{\mathrm{NaHCO}}_3$

Hence, the correct options a, b, c, d.