On heating ammonium dichromate, the gas evolved is :

Options

A. oxygen
B. ammonia
C. nitrous oxide
D. nitrogen

Answer

To solve the question regarding the gas evolved upon heating ammonium dichromate, we can follow these steps:

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

### Step 2: Write the decomposition reaction.
When ammonium dichromate is heated, it decomposes into several products. The balanced chemical equation for this reaction is:

\[ \text{2 NH}_4\text{Cr}_2\text{O}_7 (s) \rightarrow \text{N}_2 (g) + \text{4 H}_2\text{O} (g) + \text{Cr}_2\text{O}_3 (s) \]

### Step 3: Identify the gases produced.
From the balanced equation, we can see that the products of the reaction include nitrogen gas (\( \text{N}_2 \)), water vapor (\( \text{H}_2\text{O} \)), and solid chromium(III) oxide (\( \text{Cr}_2\text{O}_3 \)).

### Step 4: Determine the specific gas evolved.
The question specifically asks for the gas evolved. In this case, the gas evolved is nitrogen gas (\( \text{N}_2 \)).

### Conclusion:
Thus, the gas evolved when ammonium dichromate is heated is nitrogen gas.

### Final Answer:
The correct answer is **nitrogen gas**.

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