Which of the following has P-P linkage ?

Options

A. `H_(4) P_(2) O_(6)`
B. `H_(4) P_(2) O_(7)`
C. `HPO_(3)`
D. `H_(3) PO_(4)`

Answer

To determine which of the given compounds has a P-P (phosphorus-phosphorus) linkage, we will analyze each option by drawing their structures and identifying the presence of P-P bonds.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given in the options are:
- Option 1: H4P2O6 (Hypophosphoric acid)
- Option 2: H4P2O7 (Pyrophosphoric acid)
- Option 3: HPO3 (Metaphosphoric acid)
- Option 4: H3PO4 (Phosphoric acid)

2. **Draw the Structure of H4P2O6**:
- Hypophosphoric acid (H4P2O6) has a structure where two phosphorus atoms are linked by a single bond (P-P linkage).
- The structure can be represented as:
```
O O
\\ //
P - P
/| |\
OH OH OH OH
```

3. **Draw the Structure of H4P2O7**:
- Pyrophosphoric acid (H4P2O7) has a structure where the two phosphorus atoms are also linked, but they are connected through an oxygen atom (P-O-P), not a direct P-P bond.
- The structure can be represented as:
```
O O
\\ //
P - O - P
/| |\
OH OH OH OH
```

4. **Draw the Structure of HPO3**:
- Metaphosphoric acid (HPO3) does not have a P-P bond. It has a single phosphorus atom connected to oxygen atoms.
- The structure can be represented as:
```
O
||
P - OH
||
O
```

5. **Draw the Structure of H3PO4**:
- Phosphoric acid (H3PO4) also does not have a P-P bond. It consists of one phosphorus atom connected to four oxygen atoms.
- The structure can be represented as:
```
O
||
P - OH
/|\
OH OH
```

6. **Conclusion**: After analyzing the structures:
- **H4P2O6 (Hypophosphoric acid)** has a P-P single bond linkage.
- **H4P2O7 (Pyrophosphoric acid)** has a P-O-P linkage.
- **HPO3 (Metaphosphoric acid)** and **H3PO4 (Phosphoric acid)** do not have any P-P linkages.

Thus, the correct answer is **Option 1: H4P2O6**.