HCl was passed through a solution of `CaCl_2, MgCl_2 and NaCl` Which of the following compound(s) crystallise(s) ?

Options

A. Both`MgCl_2 and CaCl_2`
B. only NaCl
C. only `MgCl_2`
D. NaCl,`MgCl_2 and CaCl_2`

Answer

To determine which compound crystallizes when HCl is passed through a solution of CaCl₂, MgCl₂, and NaCl, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Compounds**: We have three compounds in solution: Calcium chloride (CaCl₂), Magnesium chloride (MgCl₂), and Sodium chloride (NaCl).

2. **Understand the Effect of HCl**: When HCl is added to the solution, it increases the concentration of Cl⁻ ions in the solution.

3. **Solubility of Compounds**:
- **Calcium Chloride (CaCl₂)**: This compound is highly soluble in water and will remain dissolved even when HCl is added.
- **Magnesium Chloride (MgCl₂)**: Similar to CaCl₂, MgCl₂ is also highly soluble and will not precipitate out of the solution upon the addition of HCl.
- **Sodium Chloride (NaCl)**: NaCl is also soluble in water, but the increase in Cl⁻ concentration from HCl can lead to a situation where the solubility limit of NaCl is exceeded.

4. **Precipitation of NaCl**: As HCl is added, the concentration of Cl⁻ ions increases. This can cause NaCl to precipitate out of the solution because the solubility product (Ksp) of NaCl may be exceeded, leading to crystallization.

5. **Conclusion**: Only NaCl will crystallize from the solution when HCl is passed through it, while CaCl₂ and MgCl₂ remain dissolved.

### Final Answer:
**NaCl crystallizes when HCl is passed through the solution of CaCl₂, MgCl₂, and NaCl.**