Which of the following elements does not show disproportionation tendency?

Options

A. Cl
B. Br
C. F
D. I

Explanation

To determine which of the given elements does not show disproportionation tendency, we need to understand what a disproportionation reaction is and analyze each of the options provided.

### Step-by-Step Solution:

1. **Understanding Disproportionation Reaction**:
- A disproportionation reaction is a type of redox reaction in which the same species is both oxidized and reduced. This means that the element involved must have at least three oxidation states to facilitate this process.

2. **Analyzing the Options**:
- We have four elements to consider: Chlorine (Cl), Bromine (Br), Fluorine (F), and Iodine (I).

3. **Oxidation States of Each Element**:
- **Chlorine (Cl)**: Can exhibit oxidation states of -1, 0, +1, +3, +5, and +7. Thus, it can undergo disproportionation.
- **Bromine (Br)**: Can exhibit oxidation states of -1, 0, +1, +3, +5, and +7. Thus, it can also undergo disproportionation.
- **Fluorine (F)**: The most electronegative element, it only shows an oxidation state of -1. It does not have a positive oxidation state and cannot be oxidized. Therefore, it cannot undergo disproportionation.
- **Iodine (I)**: Can exhibit oxidation states of -1, 0, +1, +3, +5, and +7. Thus, it can undergo disproportionation.

4. **Conclusion**:
- Among the given options, Fluorine (F) does not show disproportionation tendency because it cannot be oxidized to a higher oxidation state; it only exists in the -1 oxidation state.

### Final Answer:
**Fluorine (F)** does not show disproportionation tendency.