`X+HNO_(3) to Y+NO_(2)+H_(2)O+S`, Y+Ammonium molybdate`to`yellow ppt. identify X:

Options

A. `As_(2)S_(5)`
B. `Sb_(2)S_(5)`
C. `SnS_(2)`
D. `CdS`

Explanation

To identify the compound X in the given reaction sequence, we can follow these steps:

### Step 1: Understand the Reaction Sequence
The reaction involves a compound X reacting with nitric acid (HNO3) to produce a compound Y, nitrogen dioxide (NO2), water (H2O), and sulfur (S). The second part of the reaction involves compound Y reacting with ammonium molybdate to produce a yellow precipitate.

### Step 2: Analyze the Possible Compounds
The options provided for compound X are:
1. As2S5
2. Sb2S5
3. SnS2
4. Cadmium sulfide (CdS)

### Step 3: Reaction of X with HNO3
Let’s test each compound with nitric acid:

1. **For As2S5**:
- The reaction with HNO3 produces arsenic acid (H3AsO4), nitrogen dioxide (NO2), and sulfur:
\[ 4 \text{As}_2\text{S}_5 + 20 \text{HNO}_3 \rightarrow 8 \text{H}_3\text{AsO}_4 + 10 \text{NO}_2 + 5 \text{S} + 6 \text{H}_2\text{O} \]
- Here, Y = H3AsO4.

2. **For Sb2S5**:
- The reaction produces antimony acid (H3SbO4), nitrogen dioxide, and sulfur:
\[ 2 \text{Sb}_2\text{S}_5 + 12 \text{HNO}_3 \rightarrow 4 \text{H}_3\text{SbO}_4 + 10 \text{NO}_2 + 5 \text{S} + 6 \text{H}_2\text{O} \]
- Here, Y = H3SbO4.

3. **For SnS2**:
- The reaction produces stannic acid (H2SnO3), nitrogen dioxide, and sulfur:
\[ \text{SnS}_2 + 6 \text{HNO}_3 \rightarrow \text{H}_2\text{SnO}_3 + 2 \text{NO}_2 + \text{S} + 2 \text{H}_2\text{O} \]
- Here, Y = H2SnO3.

4. **For Cadmium sulfide (CdS)**:
- The reaction produces cadmium nitrate and sulfur:
\[ \text{CdS} + 4 \text{HNO}_3 \rightarrow \text{Cd(NO}_3\text{)}_2 + \text{S} + 2 \text{NO}_2 + 2 \text{H}_2\text{O} \]
- Here, Y is not an acid.

### Step 4: Reaction of Y with Ammonium Molybdate
Now we need to check which of the Y compounds reacts with ammonium molybdate to form a yellow precipitate:

1. **For H3AsO4**:
- Reacts with ammonium molybdate to form a yellow precipitate of ammonium phosphomolybdate.

2. **For H3SbO4**:
- Also forms a yellow precipitate with ammonium molybdate.

3. **For H2SnO3**:
- Does not form a yellow precipitate.

4. **For Cd(NO3)2**:
- Does not form a yellow precipitate.

### Conclusion
From the analysis, the only compound that fits the criteria for both reactions is As2S5, which produces H3AsO4 (Y) that forms a yellow precipitate with ammonium molybdate.

Thus, the identified compound X is **As2S5**.