Which gas is obtained by the thermal decomposition of ammonium dichromate?

Options

A. `O_2`
B. `NH_3`
C. `N_2`
D. NO

Answer

To determine which gas is obtained by the thermal decomposition of ammonium dichromate, we can follow these steps:

### Step 1: Identify the compound
Ammonium dichromate is represented by the chemical formula \( \text{(NH}_4)_2\text{Cr}_2\text{O}_7 \).

### Step 2: Understand thermal decomposition
Thermal decomposition involves breaking down a compound into simpler substances when heat is applied.

### Step 3: Write the decomposition reaction
When ammonium dichromate is heated, it decomposes into several products. The balanced reaction for the thermal decomposition is:

\[ \text{(NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow \text{Cr}_2\text{O}_3 + \text{N}_2 + \text{H}_2\text{O} + \text{O}_2 \]

### Step 4: Identify the gaseous products
From the balanced equation, we can see that the products include:
- Chromium(III) oxide (\( \text{Cr}_2\text{O}_3 \)) - solid
- Nitrogen gas (\( \text{N}_2 \)) - gas
- Water (\( \text{H}_2\text{O} \)) - can be in liquid or vapor form depending on temperature
- Oxygen gas (\( \text{O}_2 \)) - gas

### Step 5: Determine which gas is specifically asked for
The question specifically asks for the gas obtained from the decomposition. Among the gaseous products, nitrogen gas (\( \text{N}_2 \)) is a notable product.

### Conclusion
The gas obtained by the thermal decomposition of ammonium dichromate is **Nitrogen gas (\( \text{N}_2 \))**.

---