Assertion (A): `BaCO_(3)` is more soluble in `HNO_(3)` than in water.
Reason (R ): Carbonate is a weak base and reacts with `H^(o+)` ions to form strong acid causing barium salt to dissociate.

Options

A. If both `(A)` and `(R )` are correct and `(R )` is the correct explanation of `(A)`.
B. If both `(A)` and `(R )` are correct, but `(R )` is not the correct explanation of `(A)`.
C. If `(A)` is correct, but `(R )` is incorrect.
D. If `(A)` is incrrect, but `(R )` is correct.

Answer

To solve the given question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that BaCO₃ (barium carbonate) is more soluble in HNO₃ (nitric acid) than in water.
- This statement is true. Barium carbonate is indeed more soluble in nitric acid compared to water.

2. **Understanding the Reason:**
- The reason provided is that carbonate is a weak base and reacts with H⁺ ions to form a strong acid, which causes barium salt to dissociate.
- This statement is also true. When BaCO₃ reacts with H⁺ ions from HNO₃, it forms barium nitrate (Ba(NO₃)₂), carbon dioxide (CO₂), and water (H₂O). The reaction can be represented as:
\[ \text{BaCO}_3 + 2\text{HNO}_3 \rightarrow \text{Ba(NO}_3)_2 + \text{CO}_2 + \text{H}_2\text{O} \]
- The formation of a soluble barium salt (Ba(NO₃)₂) from the reaction indicates that the dissociation occurs, thus increasing the solubility of BaCO₃ in HNO₃.

3. **Conclusion:**
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that:
- Assertion (A) is true.
- Reason (R) is true and is the correct explanation for Assertion (A).

### Final Answer:
Both the assertion and reason are correct, and the reason is the correct explanation for the assertion.