Which of the following oxyacid is not a true peroxyacid ?

Options

A. Perbenzoic acid
B. Pernitric acid
C. Perchloric acid
D. All of these.

Explanation

To determine which of the following oxyacids is not a true peroxyacid, we need to understand the definition of a peroxyacid and analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Peroxyacids**:
- A peroxyacid is defined as an acid that contains a peroxy group (-OOH). This group is characterized by the presence of an oxygen-oxygen single bond, where one of the oxygens is part of a hydroxyl group (-OH).

2. **Analyzing the Options**:
- We have four options to consider:
- Perbenzoic acid
- Per nitric acid
- Perchloric acid
- All of these

3. **Examining Perbenzoic Acid**:
- The structure of perbenzoic acid can be represented as C6H5C(=O)OOH.
- It contains the -OOH group, which qualifies it as a true peroxyacid.

4. **Examining Per Nitric Acid**:
- The formula for per nitric acid is HNO4.
- Its structure includes the -OOH group, making it a true peroxyacid as well.

5. **Examining Perchloric Acid**:
- The formula for perchloric acid is HClO4.
- Its structure is Cl(=O)3OH, which does not contain the -OOH group. It only has a hydroxyl group (-OH) and no peroxy group.

6. **Conclusion**:
- Based on the analysis, perbenzoic acid and per nitric acid are true peroxyacids because they contain the -OOH group.
- Perchloric acid does not contain the -OOH group, making it not a true peroxyacid.

### Final Answer:
**Perchloric acid is not a true peroxyacid.**

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