In the catalytic oxidation of ammonia an oxide is formed which is used in the preparation of `HNO_3` . This oxide is

Options

A. `N_2 O_5`
B. `N_2 O_4`
C. `NO_2`
D. `NO`

Explanation

To solve the question regarding the oxide formed during the catalytic oxidation of ammonia that is used in the preparation of HNO3, we can follow these steps:

### Step 1: Understand the Process of Catalytic Oxidation of Ammonia
In the catalytic oxidation of ammonia, ammonia (NH3) is oxidized in the presence of a catalyst, typically platinum, at high temperatures (around 1100 K).

**Hint:** Remember that catalysts are substances that speed up chemical reactions without being consumed in the process.

### Step 2: Write the Balanced Chemical Equation
The balanced equation for the catalytic oxidation of ammonia can be written as:
\[ 4 \text{NH}_3 + 5 \text{O}_2 \rightarrow 4 \text{NO} + 6 \text{H}_2 \]

This shows that ammonia reacts with oxygen to produce nitrogen monoxide (NO) and hydrogen.

**Hint:** Balancing chemical equations is crucial to ensure that the number of atoms for each element is the same on both sides of the equation.

### Step 3: Identify the Oxide Formed
From the balanced equation, we see that nitrogen monoxide (NO) is the oxide formed during this reaction.

**Hint:** Pay attention to the products of the reaction to identify which oxide is formed.

### Step 4: Relate NO to HNO3 Preparation
The nitrogen monoxide (NO) can further react with oxygen (O2) to form nitrogen dioxide (NO2):
\[ 2 \text{NO} + \text{O}_2 \rightarrow 2 \text{NO}_2 \]

Then, nitrogen dioxide can react with water (H2O) to produce nitric acid (HNO3):
\[ 3 \text{NO}_2 + \text{H}_2\text{O} \rightarrow 2 \text{HNO}_3 + \text{NO} \]

**Hint:** Understanding the subsequent reactions is key to linking the oxide formed to the final product.

### Step 5: Conclusion
Thus, the oxide formed during the catalytic oxidation of ammonia that is used in the preparation of HNO3 is nitrogen monoxide (NO).

**Final Answer:** The oxide is \( \text{NO} \) (nitrogen monoxide).

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