Final answer:
Car engines emit nitrogen oxides (NOx) as a result of high combustion temperatures. Catalytic converters in cars remove NOx by converting them into dinitrogen and oxygen through a catalytic reaction using platinum-rhodium catalysts.
Step-by-step explanation:
Car engines emit nitrogen oxides (NOx) as a result of high combustion temperatures. To remove NOx from the exhaust gases, a car is equipped with a catalytic converter. The catalytic converter contains a surface impregnated with a platinum-rhodium catalyst, which catalyzes the conversion of nitric oxide into dinitrogen and oxygen. This conversion helps reduce the amount of NOx emitted by the car and contributes to controlling photochemical smog.