Dinitrogen cannot be librated by :

Options

A. decompostion of ammonium dichromate.
B. reaction of ammonia with heated cupric oxide
C. reaction of ammonia with bleaching powder.
D. heating ammonium carbonate.

Explanation

To solve the question "Dinitrogen cannot be liberated by:", we will analyze each of the given reactions step by step to determine whether dinitrogen (N₂) is produced or not.

### Step-by-Step Solution:

1. **Identify the Reactions**:
We need to analyze the following reactions:
- Decomposition of ammonium dichromate
- Reaction of ammonia with heated cupric oxide
- Reaction of ammonia with bleaching powder
- Heating of ammonium carbonate

2. **Reaction 1: Decomposition of Ammonium Dichromate**:
- **Chemical Equation**:
\[ \text{NH}_4\text{Cr}_2\text{O}_7 \rightarrow \text{Cr}_2\text{O}_3 + \text{N}_2 + 4\text{H}_2\text{O} \]
- **Analysis**:
In this reaction, dinitrogen (N₂) is produced.

3. **Reaction 2: Reaction of Ammonia with Heated Cupric Oxide**:
- **Chemical Equation**:
\[ 2\text{NH}_3 + 3\text{CuO} \rightarrow 3\text{Cu} + \text{N}_2 + 3\text{H}_2\text{O} \]
- **Analysis**:
Here, dinitrogen (N₂) is also produced.

4. **Reaction 3: Reaction of Ammonia with Bleaching Powder**:
- **Chemical Equation**:
\[ 3\text{Ca(OCl)}_2 + 2\text{NH}_3 \rightarrow 3\text{CaCl}_2 + \text{N}_2 + 3\text{H}_2\text{O} \]
- **Analysis**:
In this reaction, dinitrogen (N₂) is produced as well.

5. **Reaction 4: Heating of Ammonium Carbonate**:
- **Chemical Equation**:
\[ \text{(NH}_4)_2\text{CO}_3 \rightarrow 2\text{NH}_3 + \text{CO}_2 + \text{H}_2\text{O} \]
- **Analysis**:
In this reaction, ammonia (NH₃) and carbon dioxide (CO₂) are produced, but **no dinitrogen (N₂)** is liberated.

6. **Conclusion**:
Based on the analysis, the reaction that does not liberate dinitrogen is the **heating of ammonium carbonate**. Therefore, the correct answer is:

**Option D: Heating of Ammonium Carbonate**