When HCI gas is passed through a saturated solution of common salt, pure NaCI is Precipitated because:

Options

A. `HCl` is higly soluble in water.
B. The ionic product `[Na^(o+)] [Cl^(Theta)]` exceeds its solubility product `(K_(sp))`.
C. The `K_(sp)` of `NaCl` is lowered the presence of `HCl^(Theta)` ions.
D. `HCl` causes precipitation.

Answer

To solve the question regarding the precipitation of pure NaCl when HCl gas is passed through a saturated solution of common salt (NaCl), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Saturated Solution**:
- A saturated solution of NaCl contains Na⁺ and Cl⁻ ions in equilibrium with solid NaCl. The solubility product (Ksp) of NaCl is defined as:
\[ K_{sp} = [Na^+][Cl^-] \]
- In a saturated solution, the ionic product (IP) equals the Ksp.

2. **Effect of Adding HCl**:
- When HCl gas is passed into the solution, it dissolves to form H⁺ and Cl⁻ ions:
\[ HCl \rightarrow H^+ + Cl^- \]
- This increases the concentration of Cl⁻ ions in the solution.

3. **Common Ion Effect**:
- The increase in Cl⁻ concentration due to HCl results in a common ion effect. According to Le Chatelier's principle, if the concentration of one of the ions in a saturated solution increases, the equilibrium will shift to the left to reduce the concentration of that ion.
- This shift causes the formation of more solid NaCl, leading to precipitation.

4. **Ionic Product and Ksp**:
- With the increase in Cl⁻ ions, the product of the ionic concentrations (IP) becomes greater than the Ksp of NaCl:
\[ IP = [Na^+][Cl^-] > K_{sp} \]
- When the ionic product exceeds the solubility product, NaCl precipitates out of the solution.

5. **Conclusion**:
- Therefore, the correct reason for the precipitation of NaCl when HCl gas is passed through a saturated solution of common salt is that the ionic product of Na⁺ and Cl⁻ exceeds its solubility product (Ksp).

### Final Answer:
The correct option is: **The ionic product of Na⁺ and Cl⁻ exceeds its solubility product Ksp.**