Which of the following act both as oxidant & reductant :-

Options

A. `H_(2)S`
B. `SO_(3)`
C. `H_(2)O_(2)`
D. `F_(2)`

Answer

To determine which of the given substances can act both as an oxidant and a reductant, we need to analyze the oxidation states of each substance and see how they can change during a reaction.

### Step-by-Step Solution:

1. **Understanding Oxidants and Reductants**:
- An **oxidant** (oxidizing agent) is a substance that gains electrons and is reduced in the process.
- A **reductant** (reducing agent) is a substance that loses electrons and is oxidized in the process.

2. **Analyzing Each Substance**:
- **H₂S**:
- Sulfur in H₂S has an oxidation state of -2.
- In SO₃, sulfur has an oxidation state of +6.
- H₂S can only be oxidized to higher oxidation states (0, +2, +4, +6) but cannot be reduced further, thus it cannot act as both.

- **SO₃**:
- Sulfur in SO₃ is +6.
- It can only be reduced to lower oxidation states (0, +4, +2, -2).
- Therefore, it can act only as an oxidizing agent and not as a reducing agent.

- **H₂O₂ (Hydrogen Peroxide)**:
- In H₂O₂, the oxidation state of oxygen is -1.
- It can be oxidized to O₂ (0 oxidation state) or reduced to H₂O (-2 oxidation state).
- This means H₂O₂ can act both as an oxidant (when it is reduced) and as a reductant (when it is oxidized).

- **F₂**:
- Fluorine in F₂ has an oxidation state of 0.
- It can only be reduced to F⁻ (-1 oxidation state).
- Due to its high electronegativity, it cannot exhibit positive oxidation states, thus it can only act as an oxidizing agent.

3. **Conclusion**:
- The only substance that can act both as an oxidant and a reductant is **H₂O₂ (Hydrogen Peroxide)**.

### Final Answer:
**H₂O₂ (Hydrogen Peroxide)** is the substance that acts both as an oxidant and a reductant.

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