Which halogen does not show variable oxidation state?

Options

A. `F_(2)`
B. `CL_(2)`
C. `Br_(2)`
D. `I_(2)`

Explanation

To determine which halogen does not show a variable oxidation state, we will analyze the halogens: fluorine, chlorine, bromine, and iodine.

### Step-by-Step Solution:

1. **Identify the Halogens**: The halogens are fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

2. **Understand Oxidation States**: The oxidation states of elements indicate the degree of oxidation (loss of electrons) or reduction (gain of electrons) that an atom can undergo.

3. **Examine Fluorine**:
- Fluorine has the electronic configuration of 1s² 2s² 2p⁵.
- It has 7 valence electrons and needs 1 more electron to complete its octet.
- Due to its high electronegativity, fluorine readily accepts 1 electron, resulting in a stable negative oxidation state of -1.
- Fluorine does not have a positive oxidation state because it cannot lose electrons easily; its ionization energy is very high.

4. **Examine Other Halogens**:
- **Chlorine (Cl)**: Can exhibit oxidation states of -1, +1, +3, +5, and +7.
- **Bromine (Br)**: Can exhibit oxidation states of -1, +1, +3, +5, and +7.
- **Iodine (I)**: Can exhibit oxidation states of -1, +1, +3, +5, and +7.

5. **Conclusion**: Among the halogens, only fluorine does not show a variable oxidation state. It primarily exists in the -1 oxidation state due to its high electronegativity and inability to lose electrons.

### Final Answer:
The halogen that does not show a variable oxidation state is **Fluorine (F)**.

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