Which one of the following is the correct statement ?

Options

A. Boric acid is a protonic acid
B. Both `Tl^(3+) and Al^(3+)` ions act as oxidizing agent in aqueous solution.
C. Hydrogen bonding in `H_3BO_3` gives it a layered structure .
D. `B(Oet)_3` imparts blue colour to the burner flame.

Answer

To solve the question, we need to analyze each statement provided in the options and determine which one is correct.

### Step-by-Step Solution:

1. **Evaluate Option 1: "Boric acid is a protonic acid."**
- Boric acid (H₃BO₃) does not ionize in water to release protons (H⁺). Instead, it acts as a Lewis acid by accepting hydroxide ions (OH⁻) to form tetrahydroxyborate (BO₃OH)⁻ and hydronium ions (H₃O⁺). Therefore, this statement is **not correct**.

2. **Evaluate Option 2: "Both Tl³⁺ and Al³⁺ ions act as oxidizing agents in aqueous solution."**
- Thallium (Tl³⁺) can act as an oxidizing agent due to the inert pair effect, but aluminum (Al³⁺) typically acts as a strong reducing agent in aqueous solutions. Thus, this statement is also **not correct**.

3. **Evaluate Option 3: "Hydrogen bonding in H₃BO₃ gives it a layered structure."**
- In boric acid, each boron atom is bonded to three oxygen atoms, and each oxygen is bonded to a hydrogen atom. The hydrogen bonds between these units lead to a two-dimensional layered structure. Therefore, this statement is **correct**.

4. **Evaluate Option 4: "B(OEt)₃ imparts blue color to the burner flame."**
- Trialkyl borates, such as B(OEt)₃ (triethyl borate), typically impart a green color to the flame, not blue. Therefore, this statement is **not correct**.

### Conclusion:
The correct statement is **Option 3: Hydrogen bonding in H₃BO₃ gives it a layered structure.**

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