The pollutant usually presents in a city which generates its electricity from coal?

Analysis

The question asks for the primary pollutant associated with cities that rely on coal-fired power plants for electricity generation. To answer this, we must look at the chemical composition of coal and the by-products of its combustion.

Concept Explanation

Coal is a fossil fuel composed primarily of carbon, but it also contains significant amounts of impurities, most notably sulfur.

When coal is burned in power plants to generate electricity, the following chemical reaction occurs:

The sulfur in the coal reacts with oxygen in the air to produce Sulphur(IV) oxide (also known as sulfur dioxide). This gas is a major air pollutant and is a primary contributor to acid rain and respiratory issues in urban areas. While coal combustion can also produce carbon(II) oxide (if combustion is incomplete), Sulphur(IV) oxide is the characteristic pollutant specifically linked to the sulfur content in coal.

Step-by-Step Solution

1. Identify the source: The question specifies "electricity from coal."
2. Analyze the fuel: Coal contains carbon and sulfur impurities.
3. Analyze the combustion process: • Complete combustion of carbon produces Carbon(IV) oxide ($CO_2$). • Incomplete combustion produces Carbon(II) oxide ($CO$). • Combustion of sulfur impurities produces Sulphur(IV) oxide ($SO_2$).
4. Evaluate the options: • Fog (A): A natural weather phenomenon, not a pollutant. • Carbon(II) oxide (B): Produced by incomplete combustion of any carbon-based fuel (like petrol in cars), not specific to coal. • Smog (C): A mixture of pollutants; while coal can contribute to it, it is not the specific chemical pollutant emitted by the combustion process itself. • Sulphur(IV) oxide (D): The direct chemical product of burning the sulfur impurities found in coal.

Conclusion

Sulphur(IV) oxide is the most significant pollutant associated with coal combustion in power plants.

Exam Tip: Whenever you see a question about "coal" or "fossil fuels" and "pollution," always look for options involving Sulfur or Acid Rain. These are classic JAMB keywords!