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 oxyacid of phosphorus is dibasic, we need to analyze the given options based on the number of hydrogen ions (H⁺) they can donate.

### Step-by-Step Solution:

1. **Understanding Dibasic Acids**: A dibasic acid is one that can donate two protons (H⁺ ions) when dissolved in water. Therefore, we need to identify which of the given oxyacids can release two H⁺ ions.

2. **Analyzing the Oxyacids**:
- **H₃PO₃ (Phosphorous acid)**: This acid has three hydrogen atoms. It can donate two H⁺ ions by ionizing one of the hydroxyl (OH) groups. Therefore, it is dibasic.
- **H₃PO₄ (Phosphoric acid)**: This acid has four hydrogen atoms and can donate three H⁺ ions, making it tribasic.
- **H₃PO₂ (Hypophosphorous acid)**: This acid has two hydrogen atoms and can only donate one H⁺ ion, making it monobasic.
- **H₄P₂O₇ (Pyrophosphoric acid)**: This acid has four hydrogen atoms and can donate four H⁺ ions, making it tetrabasic.

3. **Conclusion**: Among the oxyacids of phosphorus, H₃PO₃ is the only dibasic acid because it can donate two protons.

### Final Answer:
The dibasic acid among the oxyacids of phosphorus is **H₃PO₃**.

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