Which of the following pyroacid has X-X bond

Options

A. `H_(2)S_(2)O_(7)`
B. `H_(2)S_(2)O_(5)`
C. `H_(4)P_(2)O_(5)`
D. `H_(4)P_(2)O_(6)`

Explanation

To determine which of the given pyroacids contains an X-X bond (where X represents a central atom), we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Given Pyroacids:**
The options provided are:
- H2S2O7 (Disulfuric acid)
- H2S2O5 (Pyrosulfuric acid)
- H4P2O5 (Pyrophosphoric acid)
- H4P2O6 (Hypophosphoric acid)

2. **Analyze H2S2O7 (Disulfuric Acid):**
- Structure: H2S2O7 consists of two sulfur atoms connected by oxygen atoms.
- Bonds: The structure contains sulfur-oxygen-sulfur bonds but no sulfur-sulfur (X-X) bonds.
- Conclusion: **No X-X bond present.**

3. **Analyze H2S2O5 (Pyrosulfuric Acid):**
- Structure: H2S2O5 has two sulfur atoms directly bonded to each other.
- Bonds: This structure contains a sulfur-sulfur (X-X) bond.
- Conclusion: **X-X bond is present.**

4. **Analyze H4P2O5 (Pyrophosphoric Acid):**
- Structure: H4P2O5 consists of two phosphorus atoms connected through oxygen atoms.
- Bonds: The structure contains phosphorus-oxygen-phosphorus bonds but no phosphorus-phosphorus (X-X) bonds.
- Conclusion: **No X-X bond present.**

5. **Analyze H4P2O6 (Hypophosphoric Acid):**
- Structure: H4P2O6 has two phosphorus atoms directly bonded to each other.
- Bonds: This structure contains a phosphorus-phosphorus (X-X) bond.
- Conclusion: **X-X bond is present.**

6. **Final Comparison:**
- H2S2O5 (Pyrosulfuric acid) has a sulfur-sulfur (X-X) bond.
- H4P2O6 (Hypophosphoric acid) has a phosphorus-phosphorus (X-X) bond.
- However, since the question specifically asks for a pyroacid, we conclude that **H2S2O5 (Pyrosulfuric acid)** is the correct answer as it is a pyroacid with an X-X bond.

### Final Answer:
**H2S2O5 (Pyrosulfuric acid)** is the pyroacid that has an X-X bond.

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