NOx Reduction in Exhaust Treatment

Steps:

• Internal combustion engines produce NOx pollutants like NO and NO₂ from high-temperature N₂-O₂ reactions.
• Catalytic converters use reduction reactions to convert NOx to harmless N₂ and O₂.
• Reduction targets nitrogen oxides, not carbon or water compounds.
• Among options, NO₂ is the nitrogen oxide removed by reduction.

Why D is correct:

• NO₂ undergoes reduction in catalytic converters: 2NO₂ + 4CO → 2CO₂ + N₂ + 2O₂, converting pollutant to non-toxic gases.

Why the others are wrong:

• A. CO is oxidized to CO₂, not reduced.
• B. N₂ is inert and not a pollutant.
• C. H₂O is a product, not a pollutant removed by reduction.

Final answer: D