Which of the following is insolublein yellow ammonium polysulphide?

Options

A. `CuS`
B. `As_(2)S_(3)`
C. `Sb_(2)S_(3)`
D. `SnS`

Answer

To determine which of the given compounds is insoluble in yellow ammonium polysulfide, we will analyze the solubility of each compound based on the cations they contain.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Copper sulfide (CuS)
- Arsenic sulfide (As2S3)
- Antimony sulfide (Sb2S3)
- Tin sulfide (SnS)

2. **Understand Yellow Ammonium Polysulfide**: Yellow ammonium polysulfide is a reagent used in qualitative analysis to dissolve certain metal sulfides by forming soluble polysulfide complexes.

3. **Check Solubility of Each Compound**:
- **Copper Sulfide (CuS)**: The cation here is Cu²⁺. Copper sulfide is generally insoluble in yellow ammonium polysulfide.
- **Arsenic Sulfide (As2S3)**: The cation here is As³⁺. Sulfides of arsenic (As³⁺ and As⁵⁺) are soluble in yellow ammonium polysulfide.
- **Antimony Sulfide (Sb2S3)**: The cation here is Sb³⁺. Sulfides of antimony (Sb³⁺ and Sb⁵⁺) are also soluble in yellow ammonium polysulfide.
- **Tin Sulfide (SnS)**: The cation here is Sn²⁺. Sulfides of tin (Sn²⁺ and Sn⁴⁺) are soluble in yellow ammonium polysulfide.

4. **Conclusion**: From the analysis, we find that:
- CuS is insoluble in yellow ammonium polysulfide.
- As2S3, Sb2S3, and SnS are all soluble in yellow ammonium polysulfide.

Thus, the compound that is insoluble in yellow ammonium polysulfide is **Copper Sulfide (CuS)**.

### Final Answer:
**Copper sulfide (CuS) is insoluble in yellow ammonium polysulfide.**

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