Key Facts for Flowchart:

• Step 1 catalyst: Pt/Rh gauze at 500°C — most specific NEET fact
• Step 2: NO catalyst needed — spontaneous at room temperature
• Step 3: NO is regenerated and recycled → makes process continuous
• Overall: $NH_{3}$ → $HNO_{3}$ (3-step oxidation: +3 oxidation states total increase from −3 in $NH_{3}$ to +5 in $HNO_{3}$)