An element that never has a positive oxidation state in any of its compounds is

Options

A. Boron
B. Oxygen
C. Chlorine
D. Fluorine

Explanation

To determine which element never has a positive oxidation state in any of its compounds, we can analyze the oxidation states of the given elements: boron, oxygen, chlorine, and fluorine.

### Step-by-Step Solution:

1. **Understanding Oxidation States**:
- Oxidation state refers to the degree of oxidation of an atom in a compound. It can be positive, negative, or zero.
- Elements can exhibit different oxidation states depending on the compounds they form.

2. **Analyzing Boron**:
- Boron can have oxidation states of +3 (in boron trifluoride, BF3) and -3 (in borides).
- Therefore, boron can show positive oxidation states.

3. **Analyzing Oxygen**:
- Oxygen typically has an oxidation state of -2 in most compounds (like water, H2O).
- However, it can also exhibit positive oxidation states, such as +1 (in peroxides) and +2 (in compounds with fluorine).
- Thus, oxygen can show positive oxidation states.

4. **Analyzing Chlorine**:
- Chlorine can have oxidation states ranging from -1 (in chlorides) to +7 (in compounds like ClO4-).
- Hence, chlorine can also exhibit positive oxidation states.

5. **Analyzing Fluorine**:
- Fluorine is unique among the halogens. It always has an oxidation state of -1 in its compounds (like HF).
- Fluorine does not exhibit any positive oxidation states in any of its compounds.

6. **Conclusion**:
- Among the elements analyzed, fluorine is the only element that never has a positive oxidation state in any of its compounds.

### Final Answer:
The element that never has a positive oxidation state in any of its compounds is **Fluorine**.