Boric acid is an acid because its molecule

Options

A. contains replaceable `H^(+)` ion
B. gives up a proton
C. accepts `OH^(-)` from water releasing proton
D. combines with proton from water molecule

Explanation

**Step-by-Step Solution:**

1. **Understanding Boric Acid**: Boric acid (H₃BO₃) is often classified as a weak acid. To understand why it behaves as an acid, we need to analyze its molecular structure and behavior in water.

2. **Definition of Acids**: According to the Brønsted-Lowry theory, an acid is a substance that can donate protons (H⁺ ions). However, boric acid does not donate protons in the traditional sense like strong acids do.

3. **Boric Acid's Behavior in Water**: When boric acid is dissolved in water, it interacts with water molecules. Instead of releasing H⁺ ions directly, boric acid accepts hydroxide ions (OH⁻) from water.

4. **Reaction with Water**: The reaction can be represented as:
\[ H₃BO₃ + 2H₂O \rightleftharpoons B(OH)₄⁻ + H₃O⁺ \]
In this reaction, boric acid accepts an OH⁻ ion from water, which leads to the formation of the tetrahydroxyborate ion (B(OH)₄⁻) and releases a hydronium ion (H₃O⁺).

5. **Lewis Acid Concept**: Boric acid can also be classified as a Lewis acid because it has an incomplete octet of electrons around the boron atom. This allows it to accept electron pairs from other species, such as OH⁻ ions.

6. **Conclusion**: Therefore, boric acid is considered an acid because it accepts OH⁻ ions from water, which leads to the release of protons (H⁺) in the solution, thus behaving like an acid.

**Final Answer**: Boric acid is an acid because its molecule accepts OH⁻ from water, releasing protons.

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