H2S is bubbled into 0.2 M NaCN solution which is 0.02 M in each [Cd(CN)4]2– and [Ag(CN)2]–. The H2S — AITS & Test Series Chemistry Question

Question

H2S is bubbled into 0.2 M NaCN solution which is 0.02 M in each [Cd(CN)4]2– and [Ag(CN)2]–. The H2S produces 1 × 10-9 M sulphide ion in the solution. Given: 50 3 28 2 sp 2 sp K Ag S 1 10 M ;K CdS 7.1 10 M          1 2 20 2 18 instability instability 2 4 K Ag CN 1 10 M , K Cd CN 7.8 10 M                Identify the correct statement: (A) Ag2S precipitates first from the solution. (B) CdS precipitates first from the solution. (C) None of them precipitates under the given conditions. (D) Ag2S precipitates at a sulphide concentration 1 × 10+15 M.