Please see attached question. How does increasing the path length of exhuast pipe increase amount of catalyst. Didnt understand. Pl advise

The converter consists basically of a sort of honeycomb structure of platinum and palladium.

The job of the converter is to convert oxides of nitrogen to elemental nitrogen and oxygen gases. The nitrogen is released into the atmosphere. Any carbon monoxide resulting from incomplete combustion of the fuel is converted to carbon dioxide by the oxygen gas.
Now more the length or more is the width of th epipe ,more the surface of catalyst available for the reaction.