Without losing its concentration, `ZnCl_(2)` solution can't be kept in contact with

Options

A. Pb
B. AI
C. Au
D. Ag

Answer

To solve the question "Without losing its concentration, `ZnCl_(2)` solution can't be kept in contact with," we need to analyze the behavior of zinc chloride in the presence of certain metals based on their reduction potentials.

### Step-by-Step Solution:

1. **Understanding Zinc Chloride Solution**:
- Zinc chloride (`ZnCl2`) is a salt that dissociates in solution to give zinc ions (`Zn^2+`) and chloride ions (`Cl^-`). The concentration of `Zn^2+` ions is crucial for the solution's properties.

2. **Identifying the Relevant Metals**:
- We need to determine which metal, when in contact with `ZnCl2`, will affect the concentration of `Zn^2+` ions. Common metals to consider include aluminum, copper, and others.

3. **Reduction Potentials**:
- The electrochemical series lists metals in order of their standard reduction potentials. Metals with lower reduction potentials can reduce the ions of metals with higher reduction potentials.
- For example, the standard reduction potentials are approximately:
- Aluminum (Al): -1.66 V
- Zinc (Zn): -0.76 V
- Copper (Cu): +0.34 V

4. **Comparing Reduction Potentials**:
- Since aluminum has a lower reduction potential (-1.66 V) compared to zinc (-0.76 V), aluminum can reduce zinc ions (`Zn^2+`) back to zinc metal (`Zn`).
- This means that if aluminum is in contact with `ZnCl2`, it will reduce `Zn^2+` ions to zinc metal, thus decreasing the concentration of `Zn^2+` in the solution.

5. **Conclusion**:
- Therefore, the `ZnCl2` solution cannot be kept in contact with aluminum, as it will lead to a reduction of zinc ions and a loss of concentration of the solution.

### Final Answer:
- The `ZnCl2` solution can't be kept in contact with **Aluminum (Al)**.