Question

Most hazardous metal pollutant of automobile exhaust is:
(a) Mercury (Hg)
(b) Lead (Pb)
(c) Cadmium (Cd)
(d) Copper (Cu)

Answer 1

Hint: Automobiles exhausts have a variety of organic and inorganic pollutants. They also include metallic pollutants. However, the most hazardous metal pollutant is a silvery-white or grayish metal from group 14 or IV a of the periodic table. It is the metal used in car batteries, ammunition, and radiation protection equipment.

Complete answer:
Different compounds and metals are present in the automobile exhausts. They can be organic or inorganic pollutants. Most of these are hazardous to both the environment and human health.
Of all the metallic pollutants, the most hazardous metal pollutant of automobile exhaust is lead. Lead (Pb) is a heavy metal that is denser than most metals. It is released due to the combustion of petrol as tetraethyl lead is used as an antiknock in petrol.
Lead is very harmful and an increase in its concentration causes lead poisoning or plumbism, which disturbs the nervous system, kidneys, and liver in adults and can also cause brain damage in children. About 150 to 400 mg of lead is stored in the body of an average adult and blood levels can average about 25 mg/100 ml. An increase of these levels to 70 mg/100 ml of blood is generally associated with clinical symptoms and need treatment.

So, the answer is, “Lead”.

Note: Other heavy metals like mercury, cadmium, and copper are also seen in automobile exhaust. They are also heavy metals that can be toxic to humans. Mercury toxicity also poses health hazards and hence care is needed to be taken to minimize all the metals present in vehicle exhausts.