The pair of compounds containing peroxy `(O-O)` group is 

Options

A. `H_(2)SO_(5) and PbO_(2)`
B. `HClO_(4) and H_(2)S_(2)O_(8)`
C. `P_(2)O_(5) and MnO_(2)`
D. `H_(2)SO_(5) and H_(2)S_(2)O_(8)`

Answer

To determine the pair of compounds containing a peroxy `(O-O)` group, we will analyze the structures of the given compounds step by step.

### Step 1: Identify the Compounds
The compounds we need to analyze are:
1. H₂SO₅
2. PBO₂
3. HClO₄
4. MnO₂
5. P₂O₅
6. H₂S₂O₈

### Step 2: Draw the Structures
Let's draw the structures of each compound to look for the peroxy group.

1. **H₂SO₅ (Peroxymonosulfuric acid)**:
- Structure:
```
O
||
S - O - O - H
|
OH
```
- Contains a peroxy group (O-O).

2. **PBO₂ (Lead(II) oxide)**:
- Structure:
```
O
||
Pb - O
||
O
```
- Does not contain a peroxy group.

3. **HClO₄ (Perchloric acid)**:
- Structure:
```
O
||
Cl - O - O - O - H
```
- Does not contain a peroxy group.

4. **MnO₂ (Manganese dioxide)**:
- Structure:
```
O
||
Mn - O
||
O
```
- Does not contain a peroxy group.

5. **P₂O₅ (Diphosphorus pentoxide)**:
- Structure:
```
O
||
P - O - P
||
O
```
- Does not contain a peroxy group.

6. **H₂S₂O₈ (Peroxydisulfuric acid)**:
- Structure:
```
O
||
S - O - O - S - O - O - H
|
OH
```
- Contains a peroxy group (O-O).

### Step 3: Identify the Compounds with Peroxy Groups
From the structures drawn:
- **H₂SO₅** contains a peroxy group.
- **H₂S₂O₈** also contains a peroxy group.

### Conclusion
The pair of compounds containing the peroxy `(O-O)` group is **H₂SO₅ and H₂S₂O₈**.

### Final Answer
The correct answer is **H₂SO₅ and H₂S₂O₈**.

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