Which of the following reactions does not take place?

Options

A. `F_(2)+2Cl^(-)rarr 2F^(-)+Cl_(2)`
B. `Br_(2)+2l^(-)rarr2Br^(-)+I_(2)`
C. `Cl_(2)+2Br^(-)rarr2Cl^(-)+Br_(2)`
D. `Cl_(2)+2F^(-)rarr2Cl^(-)+F_(2)`

Answer

To determine which of the given reactions does not take place, we need to analyze the electronegativities of the halogens involved in each reaction. The order of electronegativity for halogens is as follows:

**Fluorine (F) > Chlorine (Cl) > Bromine (Br) > Iodine (I)**

Now, let's examine each reaction step by step:

### Step 1: Analyze the First Reaction
**Reaction:** \( F_2 + Cl^- \rightarrow 2F^- + Cl_2 \)

- **Electronegativities:** \( \text{Electronegativity of F} > \text{Electronegativity of Cl} \)
- **Conclusion:** Fluorine will attract the shared electrons from chlorine, leading to the formation of \( F^- \) and \( Cl_2 \). This reaction will occur.

### Step 2: Analyze the Second Reaction
**Reaction:** \( Br_2 + 2I^- \rightarrow 2Br^- + I_2 \)

- **Electronegativities:** \( \text{Electronegativity of Br} > \text{Electronegativity of I} \)
- **Conclusion:** Bromine will attract the shared electrons from iodine, resulting in the formation of \( Br^- \) and \( I_2 \). This reaction will occur.

### Step 3: Analyze the Third Reaction
**Reaction:** \( Cl_2 + 2Br^- \rightarrow 2Cl^- + Br_2 \)

- **Electronegativities:** \( \text{Electronegativity of Cl} > \text{Electronegativity of Br} \)
- **Conclusion:** Chlorine will attract the shared electrons from bromine, leading to the formation of \( Cl^- \) and \( Br_2 \). This reaction will occur.

### Step 4: Analyze the Fourth Reaction
**Reaction:** \( Cl_2 + 2F^- \rightarrow F_2 + 2Cl^- \)

- **Electronegativities:** \( \text{Electronegativity of F} > \text{Electronegativity of Cl} \)
- **Conclusion:** Fluorine has a higher tendency to attract shared electrons and will not give its electrons to chlorine. Therefore, this reaction will **not** occur.

### Final Conclusion
The reaction that does not take place is:
**\( Cl_2 + 2F^- \rightarrow F_2 + 2Cl^- \)**