Which of the following will precipitate in dil. HCl
Answer Details
Among the given options, only CuS will precipitate in dilute HCl.
CuS is insoluble in dilute HCl, and hence it will precipitate when added to dilute HCl. However, the other options will dissolve in dilute HCl, and hence they will not precipitate.
ZnS will dissolve in dilute HCl to form ZnCl2 and H2S.
Na2S will react with dilute HCl to produce H2S and NaCl.
FeS will dissolve in dilute HCl to form FeCl2 and H2S.
Therefore, the correct answer is (4) CuS.