Statement I : In presence of dilute HCl, Zn2+ is not precipitated by S2– ions.Statement II : The dissociation of H2S is suppressed by addition of dilute HCl.

Solubility of ZnS is relatively higher than the sulphides of group II. So a high concentration of S-2 ions is required to cause the precipitation. If HCl is already present then the dissociation of H2S will be greatly suppresed due to common ion effect. As a result enought S-2 ions are not there to cause the precipitation.