IGCSE · Chemistry 0620 · Chemistry of the environment

Air quality & climate: IGCSE Chemistry questions with answers

Free Air quality & climate questions for IGCSE Chemistry (0620), part of Chemistry of the environment. Each question has the answer and the marking points an examiner would look for.

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Air quality & climate practice questions

Question 1Multiple choice · 1 markA* challenge

Which row shows the approximate percentages of nitrogen and oxygen in clean, dry air?

  1. A nitrogen 71%, oxygen 28%
  2. B nitrogen 78%, oxygen 21%
  3. C nitrogen 79%, oxygen 20%, carbon dioxide 1%
  4. D nitrogen 21%, oxygen 78%
Show answer

Answer: B

Question 2Multiple choice · 1 mark

Which statement describes catalytic converter?

  1. A A compound used to lower the operating temperature in the electrolysis of aluminium oxide
  2. B Able to be hammered into shape without breaking
  3. C Gases such as carbon dioxide and methane that absorb and re-emit thermal energy, causing global warming
  4. D A device that converts carbon monoxide and oxides of nitrogen into carbon dioxide and nitrogen
Show answer

Answer: D

Question 3Multiple choice · 1 markA* challenge

Air pollutants come from several sources.
1    Methane is produced mainly by the combustion of coal.
2    Sulfur dioxide is the main cause of the greenhouse effect.
3    Oxides of nitrogen are formed when nitrogen and oxygen react in hot car engines.
Which statements are correct?

  1. A 1 and 2 only
  2. B 1 and 3 only
  3. C 2 and 3 only
  4. D 3 only
Show answer

Answer: D

Question 4Structured · 5 marksA* challenge

Carbon dioxide and methane are greenhouse gases.

(a)

Explain how greenhouse gases cause climate change.

[3]
(b)

State one source of methane and one way of reducing carbon dioxide emissions.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)absorb and re-emit infrared
greenhouse gases absorb infrared (thermal) radiation emitted by the Earth B1
they re-emit it, some back towards the Earth B1
this increases the average temperature B1
3
(b)cattle/rice/landfill; renewable energy
methane: cattle digestion / rice fields / decomposition in landfill B1
CO₂: use renewable energy / plant trees / reduce fossil fuel use B1
2
Question 5Structured · 6 marks

Clean, dry air contains nitrogen, oxygen, argon and carbon dioxide.

(a)

State the approximate percentages of nitrogen and oxygen in clean, dry air.

[2]
(b)

Name two pollutant gases from car engines and one effect of each.

[4]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)78 %; 21 %
nitrogen 78 % B1
oxygen 21 % B1
2
(b)CO toxic; NOx acid rain/smog
carbon monoxide B1
toxic (reduces oxygen carried by blood) B1
oxides of nitrogen B1
acid rain / photochemical smog / respiratory problems B1
4
Question 6Structured · 3 marks

Incomplete combustion of fuels produces carbon monoxide.

(a)

Explain why carbon monoxide is dangerous.

[2]
(b)

State the conditions that cause incomplete combustion.

[1]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)binds to haemoglobin, toxic
it combines with haemoglobin B1
reducing the oxygen carried by the blood (toxic) B1
2
(b)limited oxygen
limited supply of oxygen/air B1
1

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Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in