Among the sulphides $\mathrm{CuS}$, $\mathrm{CdS}$, $\mathrm{PbS}$ and $\mathrm{As}{}_2\mathrm{S}{}_3$, the one that dissolves in yellow ammonium sulphide is

$\mathrm{As}{}_2\mathrm{S}{}_3$ is an acidic sulphide and dissolves as a soluble thioarsenate in yellow ammonium sulphide (group IIB). The sulphides of $\mathrm{Cu}$, $\mathrm{Cd}$ and $\mathrm{Pb}$ remain insoluble (group IIA).