Of the following elements, which one has the same oxidation state in all of its compounds ?

Options

A. Hydrogen
B. Fluorine
C. Carbon
D. Oxygen

Answer

To determine which element has the same oxidation state in all of its compounds from the options provided (hydrogen, chlorine, carbon, and oxygen), we can analyze the oxidation states of each element in various compounds.

### Step-by-Step Solution:

1. **Identify the Elements and Their Common Oxidation States:**
- **Hydrogen (H):** Typically has an oxidation state of +1 when bonded to non-metals and -1 when bonded to metals. Therefore, it does not have a consistent oxidation state across all compounds.
- **Chlorine (Cl):** Chlorine is known to have multiple oxidation states, including -1, +1, +3, +5, and +7. However, in most of its compounds, it predominantly exhibits an oxidation state of -1.
- **Carbon (C):** Carbon can exhibit a wide range of oxidation states, including -4, -2, 0, +2, +4, and +6, depending on the compounds it forms. Thus, it does not have a consistent oxidation state.
- **Oxygen (O):** Oxygen typically has an oxidation state of -2 in most compounds, but it can also exhibit a -1 state in peroxides and a 0 state in O2. Therefore, it does not maintain a single oxidation state.

2. **Analyze the Oxidation States:**
- From the analysis, hydrogen, carbon, and oxygen all show variable oxidation states in different compounds.
- Chlorine, while it can have multiple oxidation states, predominantly shows -1 in most of its compounds.

3. **Conclusion:**
- Among the given options, **chlorine** is the element that predominantly shows the same oxidation state of -1 in most of its compounds, making it the correct answer to the question.

### Final Answer:
**Chlorine (Cl)** is the element that has the same oxidation state (-1) in all of its compounds.