The following flow diagram represent the industrial preparation of nitric acid from ammonia:
`NH_(3)+underset(("excess air"))(O_(2)) underset(900^(@)C)overset((X))NO underset(air)overset((Y))to(Z)overset("water")toHNO_(3)+NO`
Q. Which line of entry describes the undefined reagents, products and reaction conditions?

Options

A. X-Pt, Y-cool`(-25^(@)C)`, Z-`NO_(2)`
B. X-Ni, Y-cool `(-25^(@)C)`, Z-`N_(2)O`
C. X-Fe, Y-cool `(-11^(@)C)`, Z-`NO_(2)`
D. X-Pd, Y-high pressure, Z-`N_(2)O_(3)`

Answer

To determine the undefined reagents, products, and reaction conditions in the flow diagram for the industrial preparation of nitric acid from ammonia, we can break down the process step by step.

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The first step in the reaction involves ammonia (NH₃) reacting with excess oxygen (O₂) from the air.
- **Hint**: Look for the primary reactants in the flow diagram.

2. **Determine the Reaction Conditions**:
- The reaction occurs at a temperature of 900°C.
- **Hint**: Check the temperature conditions specified in the flow diagram.

3. **Identify the Catalyst**:
- The process uses platinum as a catalyst (denoted as X in the flow diagram).
- **Hint**: Catalysts are often indicated in chemical processes and can be found in the reaction conditions.

4. **Identify the First Product**:
- The initial product formed from the reaction of NH₃ and O₂ is nitric oxide (NO).
- **Hint**: Look for the product that is formed immediately after the reactants.

5. **Further Reactions**:
- The nitric oxide (NO) is then oxidized in the presence of air (excess O₂) at lower temperatures (around -25°C) to form nitrogen dioxide (NO₂).
- **Hint**: Pay attention to the subsequent reactions that follow the initial product.

6. **Final Products**:
- The nitrogen dioxide (NO₂) undergoes hydrolysis to produce nitric acid (HNO₃) and regenerate some nitric oxide (NO).
- **Hint**: Identify the final products of the reaction sequence.

7. **Summarize the Flow Diagram**:
- The flow diagram can be summarized as follows:
- **Reactants**: NH₃ + O₂ (excess air)
- **Catalyst**: Platinum (X)
- **Conditions**: 900°C for the first reaction and -25°C for the second reaction (Y)
- **Intermediate Product**: NO (first product)
- **Final Product**: HNO₃ + NO (after hydrolysis)

### Conclusion:
Based on the breakdown, the undefined reagents, products, and reaction conditions in the flow diagram are:
- **X**: Platinum (catalyst)
- **Y**: Low temperature (-25°C)
- **Z**: Nitrogen dioxide (NO₂)

### Final Answer:
The line of entry that describes the undefined reagents, products, and reaction conditions is:
- X = Platinum (catalyst)
- Y = Low temperature (-25°C)
- Z = Nitrogen dioxide (NO₂)