A : Anhydride of carbonic acid is `CO_(2)` .
R : Carbonic acid is dibasic .

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion , then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion , then mark (2)
C. If Assertion is true statement but Reason is false , then mark (3)
D. If both Assertion and Reason are false statements , then mark (4)

Answer

To solve the assertion-reason question, we need to analyze both statements provided:

**Assertion (A):** Anhydride of carbonic acid is CO₂.
**Reason (R):** Carbonic acid is dibasic.

### Step-by-Step Solution:

1. **Understanding Carbonic Acid:**
- The formula for carbonic acid is H₂CO₃.
- Its structure consists of a central carbon atom bonded to three oxygen atoms: one with a double bond (C=O) and two with hydroxyl groups (OH).

2. **Defining Anhydrides:**
- An anhydride is formed when a water molecule is removed from an acid.
- For carbonic acid (H₂CO₃), if we remove one water molecule (H₂O), we can determine the anhydride.

3. **Removing Water from Carbonic Acid:**
- Start with H₂CO₃ and remove H₂O:
- H₂CO₃ - H₂O = CO₂
- Thus, CO₂ is indeed formed when one water molecule is removed from carbonic acid.

4. **Conclusion about Assertion (A):**
- Since we have shown that CO₂ is formed from H₂CO₃ by removing water, the assertion that "the anhydride of carbonic acid is CO₂" is correct.

5. **Analyzing the Reason (R):**
- Carbonic acid (H₂CO₃) has two hydroxyl (OH) groups attached to its structure.
- The presence of two OH groups indicates that it can donate two protons (H⁺ ions), which means it can react with two bases.
- Therefore, carbonic acid is classified as dibasic.

6. **Conclusion about Reason (R):**
- The statement that "carbonic acid is dibasic" is also correct.

7. **Final Evaluation:**
- Both the assertion (A) and the reason (R) are correct.
- However, the reason does not provide a correct explanation for the assertion, as the dibasic nature of carbonic acid is not the reason why CO₂ is its anhydride.

### Final Answer:
- Assertion (A) is correct.
- Reason (R) is correct but does not explain (A).