Which one of the following elements can show both positive and negative oxidation state ? 

Options

A. `F`
B. `I`
C. Cs
D. `Xe`

Answer

To determine which element among the given options can show both positive and negative oxidation states, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements**: The elements provided are fluorine, iodine, cesium, and xenon.

2. **Understand Oxidation States**:
- Oxidation states can be positive or negative. Positive oxidation states indicate the loss of electrons, while negative oxidation states indicate the gain of electrons.

3. **Analyze Each Element**:
- **Fluorine (F)**: Fluorine is highly electronegative and typically exhibits a -1 oxidation state. It does not show a positive oxidation state.
- **Iodine (I)**: Iodine can exhibit both positive and negative oxidation states. It commonly shows a -1 oxidation state (like other halogens) and can also show positive oxidation states (such as +1, +3, +5, +7) due to its ability to expand its valence shell and utilize empty d orbitals.
- **Cesium (Cs)**: Cesium is an alkali metal and typically shows a +1 oxidation state. It does not exhibit a negative oxidation state.
- **Xenon (Xe)**: Xenon is a noble gas and generally does not form compounds, but it can show positive oxidation states in some compounds (like +2, +4, +6). However, it does not exhibit a negative oxidation state.

4. **Conclusion**: Among the given options, iodine is the only element that can show both positive and negative oxidation states.

### Final Answer:
The element that can show both positive and negative oxidation states is **iodine**.

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