Which of the following oxide cannot act as a reducing agent ?

Options

A. `NO_2`
B. `SO_2`
C. `CO_2`
D. `ClO_2`

Answer

To determine which of the following oxides cannot act as a reducing agent, we need to analyze the oxidation states of the elements in each oxide and their ability to increase their oxidation state.

### Step-by-Step Solution:

1. **Identify the Oxides**:
We have four oxides to consider: NO2, SO2, CO2, and ClO2.

2. **Analyze NO2**:
- In NO2, nitrogen (N) has an oxidation state of +4.
- It can increase its oxidation state to +5 (in NO3^-).
- Since it can increase its oxidation state, NO2 can act as a reducing agent.

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

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

5. **Analyze ClO2**:
- In ClO2, chlorine (Cl) has an oxidation state of +4.
- It can increase its oxidation state to +7 (in ClO3^-).
- Hence, ClO2 can act as a reducing agent.

6. **Conclusion**:
- The only oxide that cannot act as a reducing agent is CO2.

### Final Answer:
**CO2 cannot act as a reducing agent.**