Passing H2S gas info a mixture of Mn+2, Ni+2,Cu+2, and Hg+2 ions in an acidified aqueous solution precipitates________?

The solubility product of Cu+2 and Hg+2 is less than that of Mn+2 and Ni+2 as the former pair belongs to second group. This is the reason, relatively lesser concentration of sulfide ions are required for the precipitation of the former pair. That is why acid is used to suppress the dissociation of H2S to obtain the desired concentration of sulfide ions to achieve the precipitation of the CuS and HgS .