Which of the following halogen can replace others?

Options

A. `I_2`
B. `Br_2`
C. `F_2`
D. `Cl_2`

Answer

To determine which halogen can replace others, we need to analyze the standard reduction potentials (SRP) of the halogens. The halogens in question are fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

### Step-by-Step Solution:

1. **Understanding the Electrochemical Series**:
- The electrochemical series ranks elements based on their standard reduction potentials (SRP). The higher the SRP, the stronger the oxidizing agent, meaning it can replace other elements in a reaction.

2. **Listing the Halogens and Their SRP**:
- The standard reduction potentials for the halogens are approximately:
- Fluorine (F₂ + 2e⁻ → 2F⁻): +2.87 V
- Chlorine (Cl₂ + 2e⁻ → 2Cl⁻): +1.36 V
- Bromine (Br₂ + 2e⁻ → 2Br⁻): +0.59 V
- Iodine (I₂ + 2e⁻ → 2I⁻): +0.54 V

3. **Analyzing the Replacement Ability**:
- A halogen can replace another halogen if it has a higher SRP.
- Fluorine has the highest SRP (+2.87 V), meaning it can replace chlorine, bromine, and iodine.
- Chlorine can replace bromine and iodine but cannot replace fluorine.
- Bromine can replace iodine but cannot replace chlorine or fluorine.
- Iodine cannot replace any of the other halogens.

4. **Conclusion**:
- The halogen that can replace all others is **Fluorine (F)**.

### Summary:
- Fluorine can replace chlorine, bromine, and iodine.
- Chlorine can replace bromine and iodine.
- Bromine can replace iodine.
- Iodine cannot replace any of the others.