A solution is 0.0100 M in each of the metal ions in the following table: Metal sulfide KspaFeS 6Ã102NiS 8Ã10â1PbS 3Ã10â7CuS 6Ã10â16

a) HCl is added to the solution so that the H3O+ concentration is 0.300 M. H2S gas is bubbled through the solution to attain a H2S concentration of 0.100 M.

b) The solution remaining from Part A, which contains 0.0100 M Ni2+ and Fe2+ ions, is still saturated with H2S gas, producing a concentration of 0.100 M. A buffer is added to this solution to produce a pH of 2.01 . Which of the following describes correctly the effect of the addition of the buffer?a) Only NiS precipitates. b) Only FeS precipitates. c) Both NiS and FeS precipitate. d) Neither NiS nor FeS precipitate.