In Ostwald's process, nitric oxide is prepared by the oxidation of 

Options

A. `NH_(3)`
B. `N_(2)`
C. Air
D. Nitrogen oxide

Answer

To solve the question regarding Ostwald's process and the preparation of nitric oxide, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding Ostwald's Process**:
Ostwald's process is a method used to produce nitric acid from ammonia. The first step in this process involves the oxidation of ammonia.

2. **Identifying the Reactant**:
In the context of the question, we need to identify what is oxidized to produce nitric oxide (NO). The key reactant here is ammonia (NH₃).

3. **Oxidation Reaction**:
The oxidation of ammonia occurs at a high temperature (around 800 degrees Celsius) and in the presence of a catalyst, typically platinum gauze. The reaction can be represented as:
\[ 4NH₃ + 5O₂ \rightarrow 4NO + 6H₂O \]
Here, ammonia (NH₃) is oxidized to produce nitric oxide (NO).

4. **Further Reactions**:
The nitric oxide produced can further react with oxygen to form nitrogen dioxide (NO₂):
\[ 2NO + O₂ \rightarrow 2NO₂ \]

5. **Formation of Nitric Acid**:
Finally, nitrogen dioxide can react with water and oxygen to produce nitric acid (HNO₃):
\[ 4NO₂ + 2H₂O + O₂ \rightarrow 4HNO₃ \]

6. **Conclusion**:
Therefore, in Ostwald's process, nitric oxide is prepared by the oxidation of ammonia.

### Final Answer:
In Ostwald's process, nitric oxide is prepared by the oxidation of **ammonia**.

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