The element which forms oxides in all oxidation states ` -1 `

Options

A. `F`
B. `P`
C. `As`
D. `Sb`

Explanation

To determine which element forms oxides in all oxidation states, including -1, we can analyze the given options step by step.

### Step 1: Identify the Elements
The options provided are:
1. Fluorine (F)
2. Phosphorus (P)
3. Arsenic (As)
4. Antimony (Sb)

### Step 2: Understand Oxidation States
Oxidation states refer to the degree of oxidation of an atom in a compound. The question specifically asks for an element that can exhibit an oxidation state of -1.

### Step 3: Analyze Each Element
- **Fluorine (F)**:
- Fluorine is a halogen and typically exhibits an oxidation state of -1 in compounds (e.g., in HF, F is -1).
- It does not have higher oxidation states as it is the most electronegative element.

- **Phosphorus (P)**:
- Phosphorus can exhibit multiple oxidation states, including +1, +3, +5, and -3, but not -1.

- **Arsenic (As)**:
- Arsenic can exhibit oxidation states of +3, +5, and -3, but not -1.

- **Antimony (Sb)**:
- Antimony can exhibit oxidation states of +3, +5, and -3, but not -1.

### Step 4: Conclusion
From the analysis, only fluorine can exhibit the oxidation state of -1. Therefore, the correct answer is:

**Fluorine (F)**, which is option A.

### Final Answer
The element which forms oxides in all oxidation states, including -1, is **Fluorine (F)**.

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