Final answer:
The catalytic converter is incompatible with leaded petrol due to the coating it creates on the catalyst's surface.
Step-by-step explanation:
The catalytic converter cannot be used in a car that uses leaded petrol because the catalyst in the converter is not compatible with lead. Leaded petrol contains tetraethyllead, a compound that can coat the surface of the catalyst, rendering it ineffective. This coating prevents the catalyst from facilitating the conversion of harmful pollutants, such as carbon monoxide and nitrogen oxides, into less harmful substances.
Instead, cars running on leaded petrol often use a different type of exhaust system, such as an oxidation catalyst, which can handle the pollutants emitted by leaded petrol.
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