The salt which responds to dilute and concentrated `H_(2)SO_(4)` is

Options

A. `Na_(2)SO_(4)`
B. `CaF_(2)`
C. `Na_(3)PO_(4)`
D. `Ba(NO_(3))_(2)`

Explanation

To solve the question regarding the salt that responds to both dilute and concentrated sulfuric acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the salts that react with sulfuric acid**:
- Sulfuric acid (H₂SO₄) can react with various salts. We need to find a salt that reacts with both dilute and concentrated sulfuric acid.

2. **Consider the properties of barium nitrate**:
- Barium nitrate (Ba(NO₃)₂) is a salt that is known to react with sulfuric acid.

3. **Reaction with dilute sulfuric acid**:
- When barium nitrate is treated with dilute sulfuric acid, it produces barium sulfate (BaSO₄) and nitric acid (HNO₃):
\[ Ba(NO_3)_2 + H_2SO_4 \rightarrow BaSO_4 \downarrow + 2 HNO_3 \]
- Here, barium sulfate precipitates as a white solid.

4. **Reaction with concentrated sulfuric acid**:
- When barium nitrate reacts with concentrated sulfuric acid, it produces barium sulfate and nitrogen dioxide (NO₂) along with water:
\[ Ba(NO_3)_2 + 2 H_2SO_4 \rightarrow BaSO_4 \downarrow + 2 HNO_3 + 2 NO_2 + H_2O \]
- In this case, nitrogen dioxide is released as a gas.

5. **Conclusion**:
- Since barium nitrate reacts with both dilute and concentrated sulfuric acid, we conclude that the salt which responds to both is **barium nitrate (Ba(NO₃)₂)**.

### Final Answer:
The salt which responds to dilute and concentrated H₂SO₄ is **barium nitrate (Ba(NO₃)₂)**.