O Level Chemistry 5070 · Topic 10

Chemistry of the environment: past paper questions

135 real questionsasked in 10 of the last 10 exam series2019–2025usually: State, Describe, Name, Give, Explain

Real questions on chemistry of the environment

The newest 20 of 74 written questions, plus 61 multiple-choice. Open one to see it on the real paper.

5070/21 · October/November 2025 · Q7c(ii)[2]
State two environmental challenges caused by the disposal of poly(ethene). (ii)
See it on the paper →
5070/21 · October/November 2025 · Q10a[1]
State the percentage by volume of oxygen in clean, dry air.
See it on the paper →
5070/21 · October/November 2025 · Q10b(i)[1]
State one adverse effect of this increasing percentage of carbon dioxide.
See it on the paper →
5070/21 · October/November 2025 · Q10b(ii)[1]
State one strategy to reduce this increase in the percentage of carbon dioxide.
See it on the paper →
5070/21 · October/November 2025 · Q10c(i)[1]
Name one other air pollutant that causes acid rain.
See it on the paper →
5070/21 · October/November 2025 · Q10c(ii)[1]
The burning of fossil fuels containing sulfur in power stations produces sulfur dioxide emissions. Describe one way these sulfur dioxide emissions are reduced.
See it on the paper →
5070/22 · October/November 2025 · Q7b(iii)[2]
State two environmental challenges caused by the disposal of plastics made of PET.
See it on the paper →
5070/22 · October/November 2025 · Q10a(i)[1]
Name one substance in river water that may be harmful. Explain why this substance may be harmful. substance explanation
See it on the paper →
5070/22 · October/November 2025 · Q10a(ii)[1]
Name one substance in river water that is beneficial. Explain why this substance is beneficial. substance explanation
See it on the paper →
5070/22 · October/November 2025 · Q10b[3]
Describe the three processes involved in the treatment of water for the domestic water supply. State the reason why each process is used. process reason process reason process reason
See it on the paper →
5070/22 · October/November 2025 · Q10c[1]
Describe a qualitative chemical test to show the presence of water. chemical test
See it on the paper →
5070/22 · May/June 2025 · Q5a(ii)[1]
The complete combustion of C 12 H 26 produces an air pollutant. State one adverse effect of this pollutant.
See it on the paper →
5070/22 · May/June 2025 · Q5b(i)[1]
State one adverse effect of sulfur dioxide as an air pollutant.
See it on the paper →
5070/21 · October/November 2024 · Q6e(i)[1]
State one adverse effect of sulfur dioxide in the air. (i)
See it on the paper →
5070/21 · October/November 2024 · Q6e(ii)[2]
Describe two ways of reducing the emissions of sulfur dioxide in the air.
See it on the paper →
5070/21 · May/June 2024 · Q1d[1]
removes tastes and odours during the treatment of the domestic water supply
See it on the paper →
5070/21 · May/June 2024 · Q6a[1]
Describe one adverse effect of increased global warming.
See it on the paper →
5070/21 · May/June 2024 · Q6b[3]
Describe how carbon dioxide causes global warming.
See it on the paper →
5070/21 · May/June 2024 · Q6d[1]
Explain one strategy to reduce global warming caused by carbon dioxide.
See it on the paper →
5070/21 · May/June 2024 · Q9d[2]
Plastics are made from polymers. Describe two environmental challenges caused by plastics.
See it on the paper →

What examiners said

Carbon monoxide was very well known. Carbon dioxide was the common incorrect response.
— Examiner report, October/November 2023, 5070/21 Q1(a) (Cambridge)

The chemical test for water was well known. Common incorrect responses included calcium oxide, sodium sulfate, lead chloride and sulfur dioxide.
— Examiner report, October/November 2023, 5070/21 Q1(b) (Cambridge)

Candidates found identifying the nitrate difficult. Carbon dioxide, sulfur dioxide, carbon monoxide, sodium sulfate and calcium oxide were all common responses.
— Examiner report, October/November 2023, 5070/21 Q1(c) (Cambridge)

Practise this topic

Answer these questions online and get each one marked against the official mark scheme, with what you missed and how to fix it.

Practise chemistry of the environment

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: (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 effects of these air pollutants: (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
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
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
Explain how oxides of nitrogen form in car engines and describe their removal by catalytic converters, e.g. 2CO + 2NO → 2CO2 + N2
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 and symbol equation for photosynthesis

Past papers, syllabus and examiner reports © UCLES (Cambridge University Press & Assessment). Questions are matched to topics from the official syllabus. AssessPro is independent and not endorsed by Cambridge.