Nitrogen is obtained by the thermal decomposition of :

Options

A. `NH_(4)Cl`
B. `NH_(4)NO_(3)`
C. `AgNO_(3)`
D. none of these

Explanation

To solve the question "Nitrogen is obtained by the thermal decomposition of:", we will analyze each option provided and determine which, if any, can produce nitrogen gas (N2) upon thermal decomposition.

### Step-by-Step Solution:

1. **Analyze Option A: NH4Cl (Ammonium Chloride)**
- When ammonium chloride is heated, it decomposes as follows:
\[ 2 \text{NH}_4\text{Cl} \rightarrow \text{NH}_3 + \text{HCl} \]
- This reaction produces ammonia (NH3) and hydrochloric acid (HCl), but no nitrogen gas (N2).
- **Conclusion**: Option A does not produce nitrogen.

2. **Analyze Option B: NH4NO3 (Ammonium Nitrate)**
- The thermal decomposition of ammonium nitrate is represented by the equation:
\[ 2 \text{NH}_4\text{NO}_3 \rightarrow \text{N}_2\text{O} + 2 \text{H}_2\text{O} \]
- This reaction produces nitrous oxide (N2O) and water (H2O), but again, no nitrogen gas (N2) is formed.
- **Conclusion**: Option B does not produce nitrogen.

3. **Analyze Option C: AgNO3 (Silver Nitrate)**
- The decomposition of silver nitrate upon heating is given by:
\[ 2 \text{AgNO}_3 \rightarrow 2 \text{Ag} + 2 \text{NO}_2 + \frac{1}{2} \text{O}_2 \]
- This reaction produces silver (Ag), nitrogen dioxide (NO2), and oxygen (O2), but does not yield nitrogen gas (N2).
- **Conclusion**: Option C does not produce nitrogen.

4. **Analyze Option D: None of these**
- Since none of the options A, B, or C produce nitrogen gas upon thermal decomposition, we conclude that the correct answer is:
- **Conclusion**: The correct answer is D: None of these.

### Final Answer:
Nitrogen is obtained by the thermal decomposition of none of the given options (D: None of these).