Among the oxyacids of phosphorous the dibasic acid is

Options

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

Answer

To determine which among the oxyacids of phosphorus is dibasic, we need to analyze the structures of the given acids and count the number of hydroxyl (OH) groups present in each. The presence of OH groups indicates the basicity of the acid. A dibasic acid has two replaceable hydrogen ions (H+), which corresponds to having two hydroxyl groups.

### Step-by-Step Solution:

1. **Identify the Oxyacids of Phosphorus**:
We need to consider the following oxyacids of phosphorus:
- H3PO2 (Phosphorous acid)
- H4P2O7 (Pyrophosphoric acid)
- HPO3 (Phosphoric acid)
- H3PO3 (Phosphorous acid)

2. **Draw the Structure of H3PO2**:
- Phosphorus (P) is at the center.
- It has one double bond with oxygen (O).
- There is one hydroxyl group (OH).
- The remaining two hydrogens are bonded to phosphorus.
- **Total OH groups = 1** (Monobasic)

3. **Draw the Structure of H4P2O7**:
- This acid has two phosphorus atoms.
- Each phosphorus has a double bond with oxygen and one hydroxyl group.
- There are additional oxygen atoms connecting the two phosphorus atoms.
- **Total OH groups = 2** (Dibasic)

4. **Draw the Structure of HPO3**:
- This acid forms a cyclic structure.
- Each phosphorus has one double bond with oxygen and one hydroxyl group.
- **Total OH groups = 1** (Monobasic)

5. **Draw the Structure of H3PO3**:
- Phosphorus has a double bond with oxygen and one hydroxyl group.
- There are two additional hydrogens bonded to phosphorus.
- **Total OH groups = 2** (Dibasic)

6. **Conclusion**:
- From the analysis, both H4P2O7 and H3PO3 have two hydroxyl groups.
- Therefore, the dibasic acids among the oxyacids of phosphorus are H4P2O7 (Pyrophosphoric acid) and H3PO3 (Phosphorous acid).

### Final Answer:
The dibasic acid among the oxyacids of phosphorus is **H4P2O7 (Pyrophosphoric acid)** and **H3PO3 (Phosphorous acid)**.