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IGCSE · Practice questions · Air pollution

Source, effect, solution.

Six original Cambridge-style questions on air pollution, acid rain and catalytic converters.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Pollutant, source, effect, fix.

01
Recall
[3 marks]

State the composition of clean, dry air.

  • About 78% nitrogen. ✓
  • About 21% oxygen. ✓
  • The rest (about 1%) is a mixture of noble gases, mainly argon, and carbon dioxide. ✓
02
Recall
[4 marks]

For each pollutant, give one source and one adverse effect: (a) carbon monoxide, (b) sulfur dioxide.

  • (a) Source: incomplete combustion of carbon-containing fuels. ✓
  • (a) Effect: toxic (stops the blood carrying oxygen). ✓
  • (b) Source: combustion of fossil fuels containing sulfur compounds. ✓
  • (b) Effect: acid rain. ✓
03
Recall
[2 marks]

Give two adverse effects of oxides of nitrogen in the air.

  • Acid rain. ✓
  • Photochemical smog (or respiratory problems). ✓
04
Explain
[3 marks]

(Extended) Explain how nitrogen monoxide forms in a car engine and write an equation for its removal in a catalytic converter.

  • Nitrogen and oxygen from the air react at the high temperature in the engine. ✓
  • N2 + O2 → 2NO ✓
  • In the converter: 2NO + 2CO → N2 + 2CO2 ✓
05
Explain
[3 marks]

Describe two ways of reducing the emission of sulfur dioxide from power stations and explain how one of them works.

  • Use low-sulfur fuels (remove sulfur from the fuel before burning). ✓
  • Flue gas desulfurisation. ✓
  • Calcium oxide, a base, reacts with the acidic sulfur dioxide in the waste gases: CaO + SO2 → CaSO3. ✓
06
Analysis
[2 marks]

A student says catalytic converters help to stop global warming. Evaluate this statement.

  • Catalytic converters remove carbon monoxide and oxides of nitrogen, reducing toxic gases and acid rain. ✓
  • But they convert CO into CO2, a greenhouse gas, so they do not reduce global warming; the statement is wrong. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.