Ionisation of boric acid in aqusous medium gives which one of the following?

Options

A. `[B(OH)_(4)]^(-)`
B. `[B(OH)_(2)O]^(-)`
C. `[B(OH)O_(2)]^(2-)`
D. `[BO_(3)]^(3-)`

Answer

To solve the question regarding the ionization of boric acid in an aqueous medium, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Identify the Formula of Boric Acid**:
- The chemical formula for boric acid is \( \text{B(OH)}_3 \).

2. **Understand the Ionization Process**:
- When boric acid is dissolved in water, it interacts with water molecules. The ionization can be represented as:
\[ \text{B(OH)}_3 + \text{H}_2\text{O} \rightarrow \text{B(OH)}_4^- + \text{H}_3\text{O}^+ \]

3. **Identify the Products of Ionization**:
- From the above equation, the products formed are:
- \( \text{B(OH)}_4^- \) (tetrahydroxyborate ion)
- \( \text{H}_3\text{O}^+ \) (hydronium ion)

4. **Determine the Nature of Boric Acid**:
- Boric acid acts as a Lewis acid because it accepts hydroxide ions (\( \text{OH}^- \)) from water, leading to the formation of the tetrahydroxyborate ion.

5. **Conclusion**:
- Therefore, the correct answer to the question "Ionization of boric acid in aqueous medium gives which one of the following?" is:
\[ \text{B(OH)}_4^- \]

### Final Answer:
The ionization of boric acid in aqueous medium gives \( \text{B(OH)}_4^- \).

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