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 given compounds is not a reducing agent, we need to analyze the oxidation states of the elements in each compound. A reducing agent is a substance that can donate electrons to another substance, thereby reducing it, while it itself gets oxidized (its oxidation state increases).

Let's examine each option:

1. **SO2 (Sulfur Dioxide)**:
- In SO2, sulfur has an oxidation state of +4.
- Sulfur can be oxidized to +6 (as in SO4^2-).
- Therefore, SO2 can act as a reducing agent because it can oxidize itself.

2. **H2O2 (Hydrogen Peroxide)**:
- In H2O2, the oxidation state of oxygen is -1.
- Oxygen can be oxidized to 0 (as in O2) or to +2 (as in F2O).
- Thus, H2O2 can also act as a reducing agent since it can oxidize itself.

3. **CO2 (Carbon Dioxide)**:
- In CO2, carbon has an oxidation state of +4.
- The maximum oxidation state of carbon is +4 (as in CO2), and it cannot be oxidized further.
- Therefore, CO2 cannot act as a reducing agent since it cannot increase its oxidation state.

4. **NO2 (Nitrogen Dioxide)**:
- In NO2, nitrogen has an oxidation state of +4.
- Nitrogen can be oxidized to +5 (as in NO3^-).
- Hence, NO2 can act as a reducing agent because it can oxidize itself.

After analyzing all the options, we conclude that **CO2** is the compound that is not a reducing agent.

### Final Answer:
**CO2 is not a reducing agent.**