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 given reactions does not take place, we need to analyze the reactions based on the concept of electronegativity. Electronegativity is the tendency of an atom to attract electrons towards itself. In the halogen group, the electronegativity decreases from fluorine to iodine as we move down the group.

### Step-by-Step Solution:

1. **Identify the Electronegativity of Halogens**:
- The order of electronegativity for halogens is:
- Fluorine (F) > Chlorine (Cl) > Bromine (Br) > Iodine (I).

2. **Analyze Each Reaction**:
- **Reaction 1**: \( F_2 + 2Cl \rightarrow 2F^- + Cl_2 \)
- Fluorine is more electronegative than chlorine, so it can attract electrons from chlorine. This reaction is possible.

- **Reaction 2**: \( Br_2 + 2I^- \rightarrow 2Br^- + I_2 \)
- Bromine is more electronegative than iodine, so it can attract electrons from iodine. This reaction is also possible.

- **Reaction 3**: \( Cl_2 + 2Br^- \rightarrow 2Cl^- + Br_2 \)
- Chlorine is more electronegative than bromine, so it can attract electrons from bromine. This reaction is possible as well.

- **Reaction 4**: \( Cl + F \rightarrow Cl^- + F^+ \)
- Here, chlorine is trying to attract electrons from fluorine. Since fluorine is more electronegative than chlorine, this reaction cannot occur. Chlorine cannot oxidize fluorine, making this reaction not possible.

3. **Conclusion**:
- The reaction that does not take place is the fourth one: \( Cl + F \rightarrow Cl^- + F^+ \).

### Final Answer:
The reaction that does not take place is option 4: \( Cl + F \rightarrow Cl^- + F^+ \).

---