IGCSE Chemistry (9–1) 0971 · Topic 10

Chemistry of the environment: past paper questions

233 real questionsasked in 10 of the last 10 exam series2019–2026usually: State, Describe, Name, Explain, Draw

Real questions on chemistry of the environment

The newest 20 of 122 written questions, plus 111 multiple-choice. Open one to see it on the real paper.

0971/32 · May/June 2026 · Q7a(i)[1]
State one source of nitrates that pollute natural water sources.
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0971/32 · May/June 2026 · Q7d[2]
Figure 7.1 shows three stages in the treatment of the domestic water supply. impure sedimentation addition on a age > — | chlorination | — — drinking water water and filtration of carbon Figure 7.1 State what happens at each stage in the treatment of the domestic water supply. sedimentation filtration (f) State the col...
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0971/42 · May/June 2026 · Q3d(i)[1]
State the term used to describe a solution containing the maximum concentration of solute.
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0971/32 · October/November 2025 · Q3c(i)[1]
State why carbon is used in the treatment of water.
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0971/32 · October/November 2025 · Q3c(ii)[1]
State why water is chlorinated.
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0971/32 · October/November 2025 · Q4g(ii)[1]
State one adverse effect to the environment of the production of carbon dioxide.
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0971/42 · October/November 2025 · Q1d[2]
Gaseous oxides of nitrogen are atmospheric pollutants. One adverse effect of oxides of nitrogen is the formation of acid rain. State two other adverse effects of oxides of nitrogen.
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0971/31 · May/June 2025 · Q1d[1]
approximately 78% of clean, dry air
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0971/31 · May/June 2025 · Q2f[1]
Sea water contains dissolved gases. Name the gas that is essential for aquatic life.
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0971/31 · May/June 2025 · Q3b(i)[1]
State one source of sulfur dioxide in the air.
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0971/31 · May/June 2025 · Q3b(ii)[1]
State one adverse effect on the environment of sulfur dioxide.
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0971/31 · May/June 2025 · Q8a[1]
River water needs to be treated to make it safe to drink. Two of the stages used in the treatment of domestic water are the addition of carbon and chlorination. Describe the reason for each of these stages. chlorination addition of carbon
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0971/31 · May/June 2025 · Q8b[1]
Describe how to test whether a sample of water is pure using boiling point.
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0971/31 · May/June 2025 · Q8c[1]
Explain why distilled water is used in practical chemistry rather than tap water.
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0971/31 · May/June 2025 · Q8d[1]
A sample of polluted air contains carbon monoxide and methane. carbon monoxide State one harmful effect of each of these air pollutants.
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0971/32 · May/June 2025 · Q1d[1]
approximately 21% of clean, dry air
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0971/32 · May/June 2025 · Q1e[1]
a gas needed for photosynthesis
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0971/32 · May/June 2025 · Q2e[1]
Sea water contains dissolved nitrate ions. State one source of nitrate ions.
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0971/32 · May/June 2025 · Q3b(i)[1]
Phosphorus is one element in NPK fertilisers. Draw a circle around one other element that is also in NPK fertilisers. krypton nickel platinum potassium
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0971/32 · May/June 2025 · Q3b(ii)[1]
State why farmers use fertilisers on fields where crops are grown.
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What examiners said

This question was well answered with most candidates identifying nitrogen as the main gas in clean, dry air.
— Examiner report, May/June 2025, 0971/31 Q1(d) (Cambridge)

Most candidates recalled oxygen as the gas essential for aquatic life. Nitrogen and hydrogen were common incorrect answers.
— Examiner report, May/June 2025, 0971/31 Q2(f) (Cambridge)

The source of sulfur dioxide was not well recalled. Most candidates confused the source with an adverse effect and suggested ‘acid rain’. A few candidates listed other air pollutants. Candidates should note that ‘factories’ unqualified is not considered a source of pollutants.
— Examiner report, May/June 2025, 0971/31 Q3(b)(i) (Cambridge)

Practise this topic

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Practise these questions

In the syllabus

10.1 Water

Describe chemical tests for the presence of water using anhydrous cobalt(II) chloride and anhydrous copper(II) sulfate
Describe how to test for the purity of water using melting point and boiling point
Explain that distilled water is used in practical chemistry rather than tap water because it contains fewer chemical impurities
State that water from natural sources may contain substances, including: (a) dissolved oxygen (b) metal compounds (c) plastics (d) sewage (e) harmful microbes (f) nitrates from fertilisers (g) phosphates from fertilisers and detergents
State that some of these substances are beneficial, including: (a) dissolved oxygen for aquatic life (b) some metal compounds provide essential minerals for life
State that some of these substances are potentially harmful, including: (a) some metal compounds are toxic (b) some plastics harm aquatic life (c) sewage contains harmful microbes which cause disease (d) nitrates and phosphates lead to deoxygenation of water and damage to aquatic life Details of the eutrophication process are not required
Describe the treatment of the domestic water supply in terms of: (a) sedimentation and filtration to remove solids (b) use of carbon to remove tastes and odours (c) chlorination to kill microbes

10.2 Fertilisers

State that ammonium salts and nitrates are used as fertilisers
Describe the use of NPK fertilisers to provide the elements nitrogen, phosphorus and potassium for improved plant growth

10.3 Air quality and climate

State the composition of clean, dry air as approximately 78% nitrogen, N2, 21% oxygen, O2 and the remainder as a mixture of noble gases and carbon dioxide, CO2
State the source of each of these air pollutants, limited to: (a) carbon dioxide from the complete combustion of carbon-containing fuels (b) carbon monoxide and particulates from the incomplete combustion of carbon- containing fuels (c) methane from the decomposition of vegetation and waste gases from digestion in animals (d) oxides of nitrogen from car engines (e) sulfur dioxide from the combustion of fossil fuels which contain sulfur compounds
State the adverse effect of these air pollutants, limited to: (a) carbon dioxide: higher levels of carbon dioxide leading to increased global warming, which leads to climate change (b) carbon monoxide: toxic gas (c) particulates: increased risk of respiratory problems and cancer (d) methane: higher levels of methane leading to increased global warming, which leads to climate change (e) oxides of nitrogen: acid rain, photochemical smog and respiratory problems (f) sulfur dioxide: acid rain
State and explain strategies to reduce the effects of these environmental issues, limited to: (a) climate change: planting trees, reduction in livestock farming, decreasing use of fossil fuels, increasing use of hydrogen and renewable energy, e.g. wind, solar (b) acid rain: use of catalytic converters in vehicles, reducing emissions of sulfur dioxide by using low-sulfur fuels and flue gas desulfurisation with calcium oxide
Describe photosynthesis as the reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light
State the word equation for photosynthesis, carbon dioxide + water → glucose + oxygen
Describe how the greenhouse gases carbon dioxide and methane cause global warming, limited to: (a) the absorption, reflection and emission of thermal energy (b) reducing thermal energy loss to space
Explain how oxides of nitrogen form in car engines and describe their removal by catalytic converters, e.g. 2CO + 2NO → 2CO2 + N2
State the symbol equation for photosynthesis, 6CO2 + 6H2O → C6H12O6 + 6O2

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