Which of the following will be precipitated when dil. HCl is added to their solution.

Options

A. `Pb(NO_(3))_(2)`
B. `CuSO_(4)`
C. `MnCl_(2)`
D. `MgCO_(3)`

Explanation

To determine which compound will be precipitated when dilute HCl is added to their solution, we can analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Compounds**: The question mentions several compounds, including lead nitrate (Pb(NO3)2), copper sulfate (CuSO4), manganese chloride (MnCl2), and magnesium carbonate (MgCO3).

2. **Understanding the Reaction with Dilute HCl**: When dilute HCl is added to a solution containing these compounds, we need to consider the solubility of the resulting products.

3. **Reaction of Lead Nitrate with Dilute HCl**:
- When lead nitrate (Pb(NO3)2) is mixed with dilute HCl, a reaction occurs:
\[ Pb(NO3)2 + 2HCl \rightarrow PbCl2 \downarrow + 2HNO3 \]
- Here, lead chloride (PbCl2) is formed, which is insoluble in water and will precipitate out as a white solid.

4. **Reaction of Copper Sulfate with Dilute HCl**:
- Copper sulfate (CuSO4) does not precipitate when mixed with dilute HCl. Instead, it remains in solution.

5. **Reaction of Manganese Chloride with Dilute HCl**:
- Manganese chloride (MnCl2) is already soluble in water, and adding dilute HCl will not cause any precipitation.

6. **Reaction of Magnesium Carbonate with Dilute HCl**:
- Magnesium carbonate (MgCO3) reacts with dilute HCl to produce magnesium chloride (MgCl2), carbon dioxide (CO2), and water (H2O):
\[ MgCO3 + 2HCl \rightarrow MgCl2 + CO2 \uparrow + H2O \]
- This reaction also does not result in a precipitate, as magnesium chloride is soluble.

7. **Conclusion**: Among the compounds analyzed, only lead nitrate (Pb(NO3)2) produces a precipitate (PbCl2) when dilute HCl is added. Therefore, the correct answer is option 1, lead nitrate.

### Final Answer:
**Lead Nitrate (Pb(NO3)2) will be precipitated when dilute HCl is added to the solution.**

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