Which one of the following compounds is not a protoric acid?

Options

A. `SO(OH)_(2)`
B. `SO_(2)(OH)_(2)`
C. `B(OH)_(2)`
D. `PO(OH)_(3)`

Explanation

To determine which of the given compounds is not a protic acid, we need to analyze the ability of each compound to donate protons (H⁺ ions) in solution. Protic acids are defined as substances that can release H⁺ ions.

### Step-by-Step Solution:

1. **Understanding Protic Acids:**
- Protic acids are substances that can donate protons (H⁺ ions) in a solution. To identify a protic acid, we look for the presence of ionizable hydrogen atoms in the molecular structure.

2. **Analyzing Each Compound:**
- **A. Sulfurous Acid (H₂SO₃):**
- Structure: H₂SO₃ has two hydrogen atoms that can ionize.
- Ionization: H₂SO₃ → H⁺ + HSO₃⁻
- Conclusion: This is a protic acid.

- **B. Sulfuric Acid (H₂SO₄):**
- Structure: H₂SO₄ has two hydrogen atoms that can ionize.
- Ionization: H₂SO₄ → H⁺ + HSO₄⁻
- Conclusion: This is also a protic acid.

- **C. Orthoboric Acid (H₃BO₃):**
- Structure: H₃BO₃ appears to have three hydrogen atoms, but only one of these can ionize.
- Ionization: The hydrogens linked to boron do not release H⁺ ions; they are not ionizable.
- Conclusion: Orthoboric acid does not act as a protic acid in the absence of water.

- **D. Phosphoric Acid (H₃PO₄):**
- Structure: H₃PO₄ has three hydrogen atoms that can ionize.
- Ionization: H₃PO₄ → H⁺ + H₂PO₄⁻
- Conclusion: This is a protic acid.

3. **Final Conclusion:**
- Among the given options, **C. Orthoboric Acid (H₃BO₃)** is not a protic acid because it does not release H⁺ ions on its own.

### Answer:
C. Orthoboric Acid (H₃BO₃) is not a protic acid.

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