On treated with dilute `H_(2)SO_(4)`, a salt gives a gas which turns lime water milky. The salt can be

Options

A. `NaHCO_(3)`
B. `Na_(2)CO_(3)`
C. `Na_(2)SO_(3)`
D. `NaNO_(2)`

Explanation

To solve the question, we need to identify the salt that, when treated with dilute H₂SO₄, produces a gas that turns lime water milky. Lime water is a solution of calcium hydroxide (Ca(OH)₂), and it turns milky when carbon dioxide (CO₂) is bubbled through it, forming calcium carbonate (CaCO₃), which is insoluble in water.

### Step-by-Step Solution:

1. **Identify the salts**: We need to consider the possible salts that could react with dilute H₂SO₄. The options given are:
- A) NaHCO₃ (Sodium bicarbonate)
- B) Na₂CO₃ (Sodium carbonate)
- C) Na₂SO₃ (Sodium sulfite)
- D) NaNO₂ (Sodium nitrite)

2. **Reactions with dilute H₂SO₄**:
- **For NaHCO₃**:
\[ \text{NaHCO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{CO}_2 \]
This reaction produces CO₂ gas, which will turn lime water milky.

- **For Na₂CO₃**:
\[ \text{Na}_2\text{CO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{CO}_2 \]
This reaction also produces CO₂ gas, which will turn lime water milky.

- **For Na₂SO₃**:
\[ \text{Na}_2\text{SO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} + \text{SO}_2 \]
This reaction produces SO₂ gas. SO₂ can also turn lime water milky, forming calcium sulfite (CaSO₃).

- **For NaNO₂**:
\[ \text{NaNO}_2 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{NO} + \text{NO}_2 + \text{H}_2\text{O} \]
This reaction produces NO and NO₂ gases, which do not turn lime water milky.

3. **Conclusion**:
- From the reactions above, we see that NaHCO₃, Na₂CO₃, and Na₂SO₃ produce gases (CO₂ and SO₂) that can turn lime water milky.
- NaNO₂ does not produce a gas that turns lime water milky.

Thus, the salts that can give a gas which turns lime water milky when treated with dilute H₂SO₄ are:
- **NaHCO₃ (Sodium bicarbonate)**
- **Na₂CO₃ (Sodium carbonate)**
- **Na₂SO₃ (Sodium sulfite)**

### Final Answer:
The salt can be **NaHCO₃, Na₂CO₃, or Na₂SO₃**.