Why cannot leaded petrol be used in a car with catalytic converter?

Leaded petrol cannot be used in a car with a catalytic converter because the lead in the petrol would damage the catalytic converter. Catalytic converters are designed to reduce the amount of harmful pollutants in car exhaust emissions, and lead is a known pollutant that can damage the catalyst in the converter. When leaded petrol is burned, the lead is released into the exhaust system and can clog the catalyst, reducing its effectiveness and potentially causing damage to the engine.