Presence of which of the following element in petrol inactivates the catalyst in catalytic converter?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Lead
Option (3) Lead — Correct. The catalytic converter has expensive metals (platinum-palladium and rhodium) as catalysts. Lead in the petrol inactivates the catalyst, so motor vehicles with catalytic converters must use unleaded petrol.
Note: This question is from Chapter 16, Environmental Issues, of the pre-rationalised NCERT book. This chapter is not in the present NCERT book (2026-27). The extract below is from the pre-rationalised edition.
NCERT Extract (Pre-rationalised edition, Chapter 16, Environmental Issues):
Air Pollution and Its Control – “… As the exhaust passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas, respectively. Motor vehicles equipped with catalytic converter should use unleaded petrol because lead in the petrol inactivates the catalyst.”