`ClO_2` is an/a

Options

A. anhydride of `HClO_2`
B. anhydride of `HClO_3`
C. mixed anhydride of `HClO_2 and HClO_3`
D. mixed anhydride of `HClO_3 and HClO_4`

Answer

To determine what `ClO2` is an anhydride of, we need to analyze the chemical structure and its relationship with other compounds.

### Step-by-Step Solution:

1. **Identify the Compound**:
- The compound in question is `ClO2`, which is chlorine dioxide.

2. **Understand Anhydrides**:
- An anhydride is a compound derived from another compound by the removal of water (H2O). In this context, we are looking for the acids from which `ClO2` can be derived.

3. **Identify Related Acids**:
- The acids related to `ClO2` are `HClO2` (chlorous acid) and `HClO3` (chloric acid).

4. **Determine the Anhydride Relationship**:
- To find out if `ClO2` is an anhydride of `HClO2` or `HClO3`, we can look at the reactions involving `ClO2`.
- When `ClO2` reacts with a base like KOH, it can produce both `KClO2` and `KClO3`, indicating that it has characteristics of both acids.

5. **Mixed Anhydride Concept**:
- Since `ClO2` can yield products from both `HClO2` and `HClO3`, it can be classified as a mixed anhydride of these two acids.

6. **Conclusion**:
- Therefore, `ClO2` is a mixed anhydride of `HClO2` and `HClO3`.

### Final Answer:
`ClO2` is a mixed anhydride of `HClO2` and `HClO3`.

---