Which of the following is a component of the car exhaust?

Analyze the question: The question asks which of the listed metals is found in car exhaust fumes. This is about air pollution from vehicles.

Concept: Car engines burn petrol (gasoline). Exhaust gases usually contain:

• Carbon monoxide (CO)
• Carbon dioxide (CO₂)
• Oxides of nitrogen (NOₓ)
• Unburnt hydrocarbons
• Sulphur dioxide (SO₂)
• Lead compounds, from the anti-knock additive tetraethyl lead, Pb(C₂H₅)₄, which was added to petrol to improve engine performance. When the fuel burns, lead compounds such as lead(II) bromide and lead(II) chloride are released into the air.

Solution: Go through the options:

• A. Aluminium: not part of fuel or its combustion products.
• B. Calcium: not found in exhaust gases.
• C. Iron: part of the engine body, but not a normal exhaust component.
• D. Zinc: not an exhaust component.
• E. Lead: yes, it comes from leaded petrol and is a well-known toxic pollutant in exhaust fumes.

Answer: E, Lead.

Tip: For pollution questions, link the pollutant to its source. Think "petrol + tetraethyl lead = lead in exhaust". Lead is a heavy metal that damages the nervous system, especially in children, which is why many countries, including Nigeria, have moved to unleaded petrol.