Question

Vehicles equipped with catalytic converters should use unleaded petrol because _________________.

• A. unleaded petrol emits more pollutants
• B. leaded petrol does not emit any pollutants
• C. lead in petrol can inactivate the catalysts of the catalytic converter
• D. unleaded petrol reacts with the catalysts to enhance their catalytic efficiency

Answer 1

The correct option is C lead in petrol can inactivate the catalysts of the catalytic converter

Catalytic converters are fitted into automobiles for reducing emission of poisonous gases. These devices use catalysts such as platinum, palladium and rhodium for catalyzing a redox reaction that would convert toxic gases and pollutants in the automobile exhaust into less-toxic pollutants.

Figure : Catalytic converter

Within the converter, unburnt hydrocarbons get converted into carbon dioxide and water, carbon monoxide gets converted to carbon dioxide and nitric oxide gets changed to nitrogen gas.

Figure : Toxic byproducts are converted to non hazardous substances

But the catalysts run a risk of being inactivated if they come in contact with the lead present in the vehicular emissions. Thus, vehicles that are equipped with catalytic converters are required to use unleaded petrol. Hence option c is correct and option d is incorrect.

Unleaded petrol emits less carbon monoxide, hydrocarbons and particulate matter compared to leaded petrol. Low levels of exposure to lead in fuel can cause cardiovascular problems in adults and adverse reproductive issues in women such as disturbing the menstrual cycle, reducing fertility, etc. So use of petrol containing lead is not recommended. Hence option a and b are incorrect.