(a) Catalytic converter.
(b) The harmful gases like CO and nitrogen oxides which are present in the automobile exhausts are removed by catalytic converters. Thereby, harmful effects of air pollution are reduced.
(c) In block 1 : Nitrogen oxides are present in the exhaust gases. They enter into reduction block of catalyst. The oxides of nitrogen react forming nitrogen and oxygen.
In block 2 : The exhaust gases enter the next block called oxidation block of the catalyst. Here, hydrocarbons and the newly formed oxygen react to form carbon dioxide.
In block 3 : The exhaust gases enter into last block from here the least harmful gases are released out.