`HgS darr+HNO_(3)("conc.") to `No dissolution.

Options

A. For precipitate formation formation reaction
B. For precipitate dissolution reaction
C. For precipitate exchange reaction
D. For no reaction

Answer

To solve the question regarding the reaction of HgS with concentrated HNO3, we will analyze the situation step by step.

### Step-by-Step Solution:

1. **Identify the Reactants**:
We have Mercury(II) sulfide (HgS) and concentrated Nitric acid (HNO3) as the reactants.

2. **Understand the Nature of the Reactants**:
- HgS is known to be an insoluble precipitate in water.
- Concentrated HNO3 is a strong oxidizing agent but may not react with all substances.

3. **Consider Possible Reactions**:
We need to evaluate the possible types of reactions that could occur:
- Precipitate formation
- Precipitate dissolution
- Precipitate exchange
- No reaction

4. **Evaluate Each Option**:
- **Option 1: Precipitate Formation Reaction**:
- For a precipitate to form, there must be a reaction that leads to the creation of an insoluble product. Since HgS is already a precipitate and no new precipitate is formed, this option is incorrect.

- **Option 2: Precipitate Dissolution Reaction**:
- This would imply that the HgS is dissolving in HNO3. However, since HgS is insoluble and does not dissolve in concentrated HNO3, this option is also incorrect.

- **Option 3: Precipitate Exchange Reaction**:
- This would require some exchange of ions or compounds leading to a new precipitate. Since there is no formation of a new precipitate or any indication of a reaction, this option is incorrect as well.

- **Option 4: No Reaction**:
- Since HgS does not react with concentrated HNO3 and remains undissolved, this option is correct.

5. **Conclusion**:
The correct answer is that there is no reaction between HgS and concentrated HNO3.

### Final Answer:
There is no dissolution of HgS when reacted with concentrated HNO3.

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