An aqueous solution contain either `Hg_2^(2+) " or " Hg^(2+)` the given solution given green ppt with `KI` solution . About the given aqueous solution which of the following is incorrect ?

Options

A. It contain `Hg_2^(2+)`
B. It contain `Hg^(2+)`
C. with `NH_3` solution it gives black precipitate
D. With NaCl solution it gives white precipitate

Answer

To solve the problem, we need to analyze the information given about the aqueous solution containing either \( \text{Hg}_2^{2+} \) or \( \text{Hg}^{2+} \) and the reaction with potassium iodide (KI) that results in a green precipitate.

### Step-by-Step Solution:

1. **Identify the ions in the solution**: The solution can contain either \( \text{Hg}_2^{2+} \) (dimercury ion) or \( \text{Hg}^{2+} \) (mercury ion).

2. **Reaction with Potassium Iodide (KI)**: When either of these ions is treated with KI, a precipitate is formed. The green precipitate indicates the formation of \( \text{Hg}_2I_2 \) (mercury(I) iodide), which is associated with the presence of \( \text{Hg}_2^{2+} \).

3. **Confirming the presence of \( \text{Hg}_2^{2+} \)**: The formation of the green precipitate specifically indicates that \( \text{Hg}_2^{2+} \) is present in the solution, as \( \text{Hg}^{2+} \) would not produce a green precipitate with KI.

4. **Evaluating the statements**:
- **Statement 1**: The solution contains \( \text{Hg}_2^{2+} \). This statement is correct.
- **Statement 2**: The solution contains \( \text{Hg}^{2+} \). This statement is incorrect because the presence of the green precipitate confirms that \( \text{Hg}_2^{2+} \) is present, not \( \text{Hg}^{2+} \).
- **Statement 3**: With ammonium solution, it gives a black precipitate. This is true as \( \text{Hg}_2^{2+} \) reacts with ammonia to form elemental mercury, which is black.
- **Statement 4**: With NaCl solution, it gives a white precipitate. This is also true as \( \text{Hg}_2^{2+} \) reacts with NaCl to form \( \text{Hg}_2Cl_2 \), which is white.

5. **Conclusion**: The only incorrect statement is that the solution contains \( \text{Hg}^{2+} \).

### Final Answer:
The incorrect statement about the given aqueous solution is that it contains \( \text{Hg}^{2+} \).