Q. Assertion : Through the use of catalytic converters, unburnt hydrocarbons are changed into carbon monoxide which in turn is changed into nitrogen oxides and water.
Reason : Motor vehicles equipped with catalytic converters should use leaded petrol to protect the catalyst from degradation.

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Solution:

A catalytic converter is a vehicle emission control device that converts toxic pollutants of the exhaust gas into less toxic pollutants by catalysing a redox reaction. Catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts, are fitted into automobiles for reducing emission of poisonous gases. Rhodium is used as reduction catalyst, palladium is used as an oxidation catalyst, and platinum is used both for oxidation and reduction. 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.