Which of the following is not a reducing agent ?

Options

A. `SO_(2)`
B. `H_(2)O_(2)`
C. `CO_(2)`
D. `NO_(2)`

Explanation

To determine which of the following substances is not a reducing agent, we need to analyze the oxidation states of the elements in each compound and see if they can increase their oxidation state by losing electrons. A reducing agent is a substance that can donate electrons to another substance, thereby reducing it while itself being oxidized.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze are SO2, H2O2, CO2, and NO2.

2. **Analyze SO2**:
- In SO2, sulfur (S) has an oxidation state of +4.
- It can increase its oxidation state to +6 (as in SO3) by losing electrons.
- Therefore, SO2 can act as a reducing agent.

3. **Analyze H2O2**:
- In H2O2, the oxidation state of oxygen (O) is -1.
- Oxygen can increase its oxidation state to 0 (as in O2) by losing electrons.
- Therefore, H2O2 can also act as a reducing agent.

4. **Analyze CO2**:
- In CO2, carbon (C) has an oxidation state of +4.
- This is the maximum oxidation state for carbon; it cannot increase its oxidation state further.
- Therefore, CO2 cannot act as a reducing agent.

5. **Analyze NO2**:
- In NO2, nitrogen (N) has an oxidation state of +4.
- Nitrogen can increase its oxidation state to +5 (as in NO3-) by losing electrons.
- Therefore, NO2 can act as a reducing agent.

6. **Conclusion**: Among the given options, CO2 is the only substance that cannot act as a reducing agent since it cannot increase its oxidation state.

### Final Answer:
The compound that is not a reducing agent is **CO2** (option C).

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