Which of the following is insoluble in yellow ammonium polysulphide? — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: In systematic qualitative analysis, Group II sulfides are divided into Group IIA (copper group) and Group IIB (arsenic group) using yellow ammonium sulfide (YAS). Step 2: Group IIB sulfides (As2S3, Sb2S3, SnS) dissolve in yellow ammonium sulfide by forming soluble thiosalts (e.g., [AsS4]3-, [SbS4]3-, [SnS3]2-). Step 3: Group IIA sulfides, including copper(II) sulfide (CuS), are completely insoluble in yellow ammonium sulfide, matching option (a).