On raction with dilute `H_(2)SO_(4)`, which of the following salts will give out a gas that turns an acidified dichromate paper green?

Options

A. `Na_(2)CO_(3)`
B. `Na_(2)S`
C. `ZnSO_(3)`
D. `FeS`

Answer

To solve the question of which salts will give out a gas that turns acidified dichromate paper green when reacted with dilute sulfuric acid, we will analyze each salt one by one.

### Step-by-Step Solution:

1. **Identify the Salts:**
The salts given are:
- Sodium carbonate (Na2CO3)
- Sodium sulfide (Na2S)
- Zinc sulfide (ZnS)
- Ferrous sulfide (FeS)

2. **Reaction of Sodium Carbonate (Na2CO3) with Dilute H2SO4:**
The reaction is:
\[ \text{Na}_2\text{CO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{CO}_2 + \text{H}_2\text{O} \]
- **Gas Produced:** Carbon dioxide (CO2).
- **Effect on Dichromate Paper:** CO2 does not turn acidified dichromate paper green.

3. **Reaction of Sodium Sulfide (Na2S) with Dilute H2SO4:**
The reaction is:
\[ \text{Na}_2\text{S} + \text{H}_2\text{SO}_4 \rightarrow \text{Na}_2\text{SO}_4 + \text{H}_2\text{S} \]
- **Gas Produced:** Hydrogen sulfide (H2S).
- **Effect on Dichromate Paper:** H2S turns acidified dichromate paper green.

4. **Reaction of Zinc Sulfide (ZnS) with Dilute H2SO4:**
The reaction is:
\[ \text{ZnS} + \text{H}_2\text{SO}_4 \rightarrow \text{ZnSO}_4 + \text{H}_2\text{S} \]
- **Gas Produced:** Hydrogen sulfide (H2S).
- **Effect on Dichromate Paper:** H2S turns acidified dichromate paper green.

5. **Reaction of Ferrous Sulfide (FeS) with Dilute H2SO4:**
The reaction is:
\[ \text{FeS} + \text{H}_2\text{SO}_4 \rightarrow \text{FeSO}_4 + \text{H}_2\text{S} \]
- **Gas Produced:** Hydrogen sulfide (H2S).
- **Effect on Dichromate Paper:** H2S turns acidified dichromate paper green.

### Conclusion:
- The salts that produce a gas which turns acidified dichromate paper green are:
- Sodium sulfide (Na2S)
- Zinc sulfide (ZnS)
- Ferrous sulfide (FeS)

### Final Answer:
The correct options are **Sodium sulfide (Na2S)**, **Zinc sulfide (ZnS)**, and **Ferrous sulfide (FeS)**.

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