Which of the following reactions does not take place?

Options

A. `F_(2) + 2Cl^(-) to 2F^(-) + Cl_(2)`
B. `Br_(2) + 2I^(-) to 2Br^(-) + I_(2)`
C. `Cl_(2) + 2Br^(-) to 2Cl^(-) + Br_(2)`
D. `Cl_(2) + 2F^(-) to 2Cl^(-) + F_(2)`

Answer

To determine which of the following reactions does not take place, we need to analyze the halogen reactivity based on their atomic numbers.

### Step-by-step Solution:

1. **Understanding Halogen Reactivity**:
- Halogens are elements in Group 17 of the periodic table. They include Fluorine (F), Chlorine (Cl), Bromine (Br), and Iodine (I).
- The reactivity of halogens decreases as you move down the group. This means that a halogen with a lower atomic number can oxidize a halide ion of a halogen with a higher atomic number.

2. **Identify the Halogens**:
- In the given reaction, we have Cl2 (Chlorine) and F- (Fluoride ion).
- Chlorine (Cl) has an atomic number of 17, while Fluorine (F) has an atomic number of 9.

3. **Analyzing the Reaction**:
- The reaction in question is:
\[ Cl_2 + 2F^- \rightarrow 2Cl^- + F_2 \]
- Here, Cl2 is trying to oxidize F- to form F2.

4. **Applying the Reactivity Rule**:
- According to the reactivity rule, since Fluorine has a lower atomic number than Chlorine, it cannot be oxidized by Chlorine. Therefore, the proposed reaction cannot occur.

5. **Conclusion**:
- The reaction Cl2 + 2F- → 2Cl- + F2 does not take place because Cl2 cannot oxidize F- to form F2.

### Final Answer:
The reaction that does not take place is:
**Option D: Cl2 + 2F- → 2Cl- + F2**