Question

Most hazardous metal pollutant of automobile exhaust is

• A. Mercury (Hg)
• B. Lead (Pb)
• C. Cadmium (Cd)
• D. Copper (Cu)

Answer 1

The correct option is B

Lead (Pb)

Explanation for correct options:

Option (b) Lead ($\mathrm{Pb}$)

• Heavy metal contaminants include Lead, Cadmium, Copper, and Mercury.
• The most immobile heavy metal contaminant is Lead.
• Lead poisoning is localised due to its immobility.
• Lead is a common contaminant emitted by dry cell and battery production factories, as well as automotive emissions.
• Tetraethyl and tetramethyl Lead are used as antiknock agents in gasoline.
• Thus, this option is correct.

Explanation for incorrect options

Option (a) Mercury ($\mathrm{Hg}$)

• Mercury ($\mathrm{Hg}$) is a hazardous, bioaccumulative, and persistent contaminant.
• When discharged into the environment, it accumulates in water-deposited sediments, converting to poisonous methylmercury and entering the food chain.

Option(c) Cadmium ($\mathrm{Cd}$)

• Cadmium ($\mathrm{Cd}$) is a hazardous heavy metal that is a contaminant in the environment.
• Cadmium concentrations in the environment vary greatly.
• There are several recognized sources of Cd exposure in humans, including employment in primary metal industries, the manufacturing of specific batteries, foods, soil, and cigarette smoke.

Option (d) Copper ($\mathrm{Cu}$)

• Copper ($\mathrm{Cu}$) may disrupt soil activity by negatively influencing the activity of microorganisms and earthworms.
• Because of this, organic matter decomposition may be significantly slowed.

Hence, the correct option is (b) lead.