`SO_2` is not a

Options

A. reducing agent
B. disinfectant
C. basic oxide
D. bleaching agent

Explanation

To determine which statement is correct regarding sulfur dioxide (`SO_2`), we need to analyze the options provided. The options are:

A) Optional reducing agent
B) Disinfectant
C) Basic oxide
D) Bleaching agent

### Step-by-Step Solution:

1. **Understanding the Nature of `SO_2`:**
- Sulfur dioxide is known to be a gas that can act in various chemical reactions. It is important to understand its properties to evaluate the options.

2. **Evaluating `SO_2` as a Reducing Agent:**
- `SO_2` can act as a reducing agent. For example, when it reacts with bromine in the presence of water, it forms sulfuric acid (`H_2SO_4`). This indicates that `SO_2` can donate electrons, thus acting as a reducing agent.

3. **Evaluating `SO_2` as a Disinfectant:**
- `SO_2` has disinfectant properties. It can disrupt the activity of enzymes and proteins in microbes, which helps in killing them or inhibiting their growth. Therefore, `SO_2` can be classified as a disinfectant.

4. **Evaluating `SO_2` as a Basic Oxide:**
- Basic oxides are substances that produce hydroxide ions when dissolved in water, forming an alkali. `SO_2`, when dissolved in water, forms sulfurous acid (`H_2SO_3`), which is acidic. Therefore, `SO_2` is not a basic oxide; it is an acidic oxide.

5. **Evaluating `SO_2` as a Bleaching Agent:**
- `SO_2` can act as a bleaching agent as well. It reacts with certain dyes and can lead to the formation of colorless compounds, effectively bleaching the material.

6. **Conclusion:**
- Among the options provided, the only statement that is incorrect is that `SO_2` is a basic oxide. Therefore, the correct answer is option C: `SO_2` is not a basic oxide.

### Final Answer:
**C) Basic oxide**