Carbonic acid is a

Options

A. Weak tribasic acid
B. Weak dibasic acid
C. Strong tribasic acid
D. Strong dibasic acid

Answer

**Step-by-Step Solution:**

1. **Understanding Carbonic Acid**: Carbonic acid is represented by the chemical formula H₂CO₃. It is formed when carbon dioxide (CO₂) dissolves in water.

2. **Identifying the Type of Acid**: To classify carbonic acid, we need to determine how many hydrogen ions (H⁺) it can donate when it dissociates in solution. An acid is classified as:
- Monobasic: Can donate 1 H⁺ ion.
- Dibasic: Can donate 2 H⁺ ions.
- Tribasic: Can donate 3 H⁺ ions.

3. **Dissociation of Carbonic Acid**: When carbonic acid dissociates, it can release two H⁺ ions:
- The first dissociation:
\[ \text{H}_2\text{CO}_3 \rightleftharpoons \text{H}^+ + \text{HCO}_3^- \]
- The second dissociation:
\[ \text{HCO}_3^- \rightleftharpoons \text{H}^+ + \text{CO}_3^{2-} \]

4. **Conclusion on Basicity**: Since carbonic acid can donate a total of 2 H⁺ ions, it is classified as a dibasic acid.

5. **Weakness of Carbonic Acid**: Carbonic acid is considered a weak acid because it does not completely dissociate in solution. This means that at equilibrium, both the undissociated H₂CO₃ and the dissociated ions (H⁺ and HCO₃⁻) are present in the solution.

6. **Final Answer**: Therefore, the correct classification of carbonic acid is that it is a weak dibasic acid.

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