A precipitate of ……would be obtained on adding HCI to a solution of `As_(2)S_(3)` in yellow ammonium salphide

Options

A. `As_(2)S_(3)`
B. `AsS_(3)`
C. `As_(2)S_(6)`
D. `AsS_(2)`

Answer

To solve the problem step by step, we will analyze the reaction that occurs when hydrochloric acid (HCl) is added to a solution of arsenic trisulfide (As₂S₃) in yellow ammonium sulfide.

### Step 1: Identify the Components
We start with a solution of arsenic trisulfide (As₂S₃) in yellow ammonium sulfide (NH₄)₂S. Yellow ammonium sulfide is a source of sulfide ions (S²⁻) which can react with arsenic species.

**Hint:** Recognize the compounds involved and their states in the solution.

### Step 2: Reaction with Ammonium Sulfide
When As₂S₃ is mixed with yellow ammonium sulfide, a reaction occurs that leads to the formation of a thiosalt. The reaction can be represented as follows:

\[ \text{As}_2\text{S}_3 + 3 \text{(NH}_4)_2\text{S} \rightarrow 2 \text{NH}_4\text{AsS}_4 \]

This thiosalt is ammonium arsenic tetrasulfide (NH₄)₃AsS₄.

**Hint:** Look for the formation of new compounds when reactants are mixed.

### Step 3: Reaction with Hydrochloric Acid
Next, when hydrochloric acid (HCl) is added to the thiosalt (NH₄)₃AsS₄, a precipitate forms. The reaction can be summarized as:

\[ \text{NH}_4\text{AsS}_4 + 6 \text{HCl} \rightarrow \text{As}_2\text{S}_6 + 6 \text{NH}_4\text{Cl} + 3 \text{H}_2\text{S} \]

In this reaction, arsenic hexasulfide (As₂S₆) precipitates out of the solution.

**Hint:** Consider how acids can react with sulfides to form precipitates.

### Step 4: Identify the Precipitate
From the above reaction, we can see that the precipitate formed when HCl is added to the solution is arsenic hexasulfide (As₂S₆).

**Hint:** Focus on the final product of the reaction to determine the precipitate.

### Conclusion
Thus, the precipitate obtained on adding HCl to a solution of As₂S₃ in yellow ammonium sulfide is As₂S₆.

**Final Answer:** The precipitate formed is **As₂S₆**.