`NH_(3)+O_(2) underset(Delta)overset(Pt) to A+H_(2)O`
`A+O_(2) to B`,
`B+O_(2)+H_(2)OtoC`
A, B and C are:

Options

A. `NO , NO_(2) , and HNO_(3)`
B. `NO_2 , NO` and `HNO_3`
C. NO_2 , HNO_3 ` and `N_2 O`
D. N_2 O , NO` and `HNO_3`

Answer

To solve the problem step by step, we will analyze the given reactions and identify the compounds A, B, and C.

### Step 1: Identify Compound A
The first reaction given is:
\[ \text{NH}_3 + \text{O}_2 \xrightarrow{\Delta, \text{Pt}} A + \text{H}_2\text{O} \]

- Ammonia (NH₃) reacts with oxygen (O₂) in the presence of platinum (Pt) as a catalyst and heat (Δ).
- This reaction typically produces nitric oxide (NO) and water (H₂O).

Thus, we can conclude:
\[ A = \text{NO} \]

### Step 2: Identify Compound B
The next reaction is:
\[ A + \text{O}_2 \to B \]

- Here, we substitute A with NO:
\[ \text{NO} + \text{O}_2 \to B \]
- The reaction of nitric oxide (NO) with oxygen (O₂) produces nitrogen dioxide (NO₂).

Thus, we can conclude:
\[ B = \text{NO}_2 \]

### Step 3: Identify Compound C
The final reaction is:
\[ B + \text{O}_2 + \text{H}_2\text{O} \to C \]

- Substituting B with NO₂:
\[ \text{NO}_2 + \text{O}_2 + \text{H}_2\text{O} \to C \]
- The reaction of nitrogen dioxide (NO₂) with oxygen and water typically produces nitric acid (HNO₃).

Thus, we can conclude:
\[ C = \text{HNO}_3 \]

### Summary of Results
- A = NO (Nitric Oxide)
- B = NO₂ (Nitrogen Dioxide)
- C = HNO₃ (Nitric Acid)

### Final Answer
The correct option is:
- A: NO, B: NO₂, C: HNO₃

---