Which of the following can act as oxidising as well as reducing agent?

Options

A. `H_(2)O_(2)`
B. `SO_(3)`
C. `H_(2)SO_(4)`
D. `HNO_(3)`

Answer

To determine which of the given compounds can act as both an oxidizing agent and a reducing agent, we need to analyze the oxidation states of the elements in each compound.

### Step-by-step Solution:

1. **Understanding Oxidizing and Reducing Agents**:
- An oxidizing agent is a substance that gains electrons and is reduced in a chemical reaction.
- A reducing agent is a substance that loses electrons and is oxidized in a chemical reaction.
- A compound can act as both if it is not in its highest or lowest oxidation state.

2. **Analyzing the Options**:
- The options given are: H2O2, SO3, H2SO4, and HNO3.

3. **Analyzing H2O2 (Hydrogen Peroxide)**:
- In H2O2, the oxidation state of oxygen is -1 (since H is +1).
- Oxygen can exist in different oxidation states:
- It can be -2 (as in H2O),
- 0 (as in O2),
- and -1 (as in H2O2).
- Therefore, oxygen in H2O2 can act as both an oxidizing agent (by going from -1 to 0) and a reducing agent (by going from -1 to -2).
- **Conclusion**: H2O2 can act as both an oxidizing and reducing agent.

4. **Analyzing SO3 (Sulfur Trioxide)**:
- In SO3, the oxidation state of sulfur is +6.
- This is the highest oxidation state for sulfur, meaning it can only act as an oxidizing agent (it cannot gain more electrons).
- **Conclusion**: SO3 cannot act as a reducing agent.

5. **Analyzing H2SO4 (Sulfuric Acid)**:
- In H2SO4, sulfur also has an oxidation state of +6.
- Similar to SO3, this is the highest oxidation state for sulfur, so it can only act as an oxidizing agent.
- **Conclusion**: H2SO4 cannot act as a reducing agent.

6. **Analyzing HNO3 (Nitric Acid)**:
- In HNO3, nitrogen has an oxidation state of +5.
- This is the highest oxidation state for nitrogen, meaning it can only act as an oxidizing agent.
- **Conclusion**: HNO3 cannot act as a reducing agent.

7. **Final Answer**:
- Among the options provided, only H2O2 can act as both an oxidizing agent and a reducing agent.