The following compounds are heated (i) `NH_(4)Cl` (ii) `NH_(4)NO_(2)` (iii) `(NH_(4))_(2)Cr_(2)O_(7)` (iv) `(NH_(4))_(2)CO_(3)` . Which of the following statement/s is/are correct ?

Options

A. (i) and (iv) liberate `NH_(3)`
B. (iv) liberates `CO_(2)`
C. (ii) and (iii) liberate `N_(2)`
D. All statements are correct

Answer

To determine which statements are correct regarding the heating of the given compounds, we will analyze each compound one by one and summarize the products formed during their decomposition.

### Step-by-Step Solution

1. **Heating of Ammonium Chloride (NH₄Cl)**:
- When ammonium chloride is heated, it decomposes into hydrogen chloride (HCl) and ammonia gas (NH₃).
- **Reaction**:
\[ NH_4Cl \rightarrow NH_3 + HCl \]
- **Conclusion**: NH₄Cl liberates ammonia.

2. **Heating of Ammonium Nitrite (NH₄NO₂)**:
- Upon heating, ammonium nitrite decomposes to produce water (H₂O) and nitrogen gas (N₂).
- **Reaction**:
\[ NH_4NO_2 \rightarrow N_2 + 2H_2O \]
- **Conclusion**: NH₄NO₂ liberates nitrogen.

3. **Heating of Ammonium Dichromate \((NH₄)_2Cr_2O_7\)**:
- When heated, ammonium dichromate decomposes to form chromium(III) oxide (Cr₂O₃), water (H₂O), and nitrogen gas (N₂).
- **Reaction**:
\[ (NH_4)_2Cr_2O_7 \rightarrow Cr_2O_3 + 2N_2 + 4H_2O \]
- **Conclusion**: \((NH₄)_2Cr_2O_7\) liberates nitrogen.

4. **Heating of Ammonium Carbonate \((NH₄)_2CO_3\)**:
- On heating, ammonium carbonate decomposes to yield water (H₂O), carbon dioxide (CO₂), and ammonia gas (NH₃).
- **Reaction**:
\[ (NH_4)_2CO_3 \rightarrow 2NH_3 + H_2O + CO_2 \]
- **Conclusion**: \((NH₄)_2CO_3\) liberates ammonia and carbon dioxide.

### Summary of Findings:
- **NH₄Cl**: Liberates ammonia (NH₃).
- **NH₄NO₂**: Liberates nitrogen (N₂).
- **(NH₄)₂Cr₂O₇**: Liberates nitrogen (N₂).
- **(NH₄)₂CO₃**: Liberates ammonia (NH₃) and carbon dioxide (CO₂).

### Conclusion:
Based on the analysis:
- The first and fourth compounds liberate ammonia.
- The fourth compound liberates carbon dioxide.
- The second and third compounds liberate nitrogen.

Thus, all statements regarding the heating of these compounds are correct.

### Final Answer:
All statements are correct.

---