Water
10.1What the syllabus asks of you
- 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
Read the notes first
Chapter 10: Water
Drill this topic
Every question on Water, untimed, marked as you go.
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Choose the years and how many questions, then print it with the answers on separate pages.
35 questions
1May / June 2026 · Paper 11 · Q28Show mark scheme →
Ablue to pink | white to blue | 100
Bblue to pink | white to blue | >100
Cwhite to blue | blue to pink | 100
Dwhite to blue | blue to pink | >100
Mark scheme
2May / June 2026 · Paper 12 · Q29Show mark scheme →
Ablue to pink
Bblue to white
Cpink to blue
Dwhite to blue
Mark scheme
3Oct / Nov 2025 · Paper 11 · Q28Show mark scheme →
Acarbon
Bchlorine
Cfluorine
Dsilver
Mark scheme
4Oct / Nov 2025 · Paper 12 · Q28Show mark scheme →
A1 and 2
B1 and 3
C2 and 3
D3 only
Mark scheme
5May / June 2025 · Paper 11 · Q29Show mark scheme →
Acauses the sedimentation of some solids; removes tastes from the water
Bcauses the sedimentation of some solids; removes dissolved oxygen from the water
Ckills some microbes; removes tastes from the water
Dkills some microbes; removes dissolved oxygen from the water
Mark scheme
6May / June 2025 · Paper 12 · Q29Show mark scheme →
Asedimentation and filtration: kills microbes; treatment with chlorine: removes solids; treatment with carbon: removes unpleasant tastes and odours
Bsedimentation and filtration: removes solids; treatment with chlorine: kills microbes; treatment with carbon: removes unpleasant tastes and odours
Csedimentation and filtration: removes solids; treatment with chlorine: removes unpleasant tastes and odours; treatment with carbon: kills microbes
Dsedimentation and filtration: removes unpleasant tastes and odours; treatment with chlorine: kills microbes; treatment with carbon: removes solids
Mark scheme
7Oct / Nov 2024 · Paper 11 · Q22Show mark scheme →
Aanhydrous | blue and crystalline | hydrated | white and powdery
Bhydrated | colourless and crystalline | anhydrous | blue and powdery
Chydrated | blue and powdery | anhydrous | colourless and crystalline
Dhydrated | blue and crystalline | anhydrous | white and powdery
Mark scheme
8Oct / Nov 2024 · Paper 11 · Q28Show mark scheme →
Aremoves nitrates, removes solids, removes nitrates
Bkills microbes, removes soluble compounds, removes solids
Cremoves solids, kills microbes, removes soluble compounds
Dkills microbes, removes solids, removes solids
Mark scheme
9Oct / Nov 2024 · Paper 12 · Q39Show mark scheme →
Aimpure water | not water | pure water
Bimpure water | pure water | impure water
Cpure water | impure water | not water
Dpure water | not water | impure water
Mark scheme
10May / June 2024 · Paper 12 · Q30Show mark scheme →
AAnhydrous cobalt(II) chloride turns from blue to white.
BAnhydrous cobalt(II) chloride turns from pink to blue.
CAnhydrous copper(II) sulfate turns from blue to pink.
DAnhydrous copper(II) sulfate turns from white to blue.
Mark scheme
11Oct / Nov 2023 · Paper 11 · Q30Show mark scheme →
AChlorine is used to remove tastes and odours in the treatment of the domestic water supply.
BMetal compounds from detergents can deoxygenate natural sources of water.
CPhotosynthesis provides the oxygen needed for aquatic life in natural sources of water.
DSedimentation removes nitrates in the treatment of the domestic water supply.
Mark scheme
12Oct / Nov 2023 · Paper 12 · Q30Show mark scheme →
ADistillation is used to remove insoluble impurities from the domestic water supply.
BWater containing impurities turns anhydrous copper(II) sulfate blue.
CWater containing impurities turns cobalt(II) chloride paper blue.
DWater containing impurities boils at 100 °C.
Mark scheme
13May / June 2023 · Paper 11 · Q30Show mark scheme →
Aacid rain
Bexcess calcium hydroxide
Cinsoluble nitrates
Dsoluble fertilisers
Mark scheme
14May / June 2023 · Paper 11 · Q31Show mark scheme →
A1
B2
C3
D4
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15May / June 2023 · Paper 12 · Q32Show mark scheme →
AIt acts as a filter to remove insoluble solids.
BIt adds oxygen to the water.
CIt disinfects the water.
DIt removes tastes and odours.
Mark scheme
16Oct / Nov 2022 · Paper 11 · Q35Show mark scheme →
Ato remove mud and other insoluble solids
Bto remove nitrates caused by the excessive use of fertiliser
Cto remove tastes and odours
Dto sterilise the water by removing harmful bacteria
Mark scheme
17Oct / Nov 2022 · Paper 12 · Q35Show mark scheme →
ADecreased levels of mineral salts caused the eutrophication.
BDesalination of the river water occurred.
CIncreased levels of phosphates caused the eutrophication.
DOxygen levels in the river water increased.
Mark scheme
18Oct / Nov 2021 · Paper 12 · Q35Show mark scheme →
A1, 2 and 3
B1 and 2 only
C2 and 3 only
D3 only
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19Oct / Nov 2020 · Paper 11 · Q33Show mark scheme →
ABoth statements are correct and statement 2 explains statement 1.
BBoth statements are correct but statement 2 does not explain statement 1.
CStatement 1 is correct but statement 2 is incorrect.
DStatement 2 is correct but statement 1 is incorrect.
Mark scheme
20Oct / Nov 2020 · Paper 12 · Q33Show mark scheme →
Ause of carbon Y; desalination Z; chlorination W; filtration X
Buse of carbon Z; desalination Y; chlorination W; filtration X
Cuse of carbon Z; desalination Y; chlorination X; filtration W
Duse of carbon Y; desalination Z; chlorination X; filtration W
Mark scheme
21May / June 2020 · Paper 11 · Q32Show mark scheme →
Aadding chlorine to kill bacteria
Bboiling the water to sterilise it
Cremoving the salt by filtration
Dseparating the water by distillation
Mark scheme
22May / June 2020 · Paper 12 · Q32Show mark scheme →
Afractional distillation ✓, desalination ✓
Bfractional distillation ✓, desalination ✗
Cfractional distillation ✗, desalination ✓
Dfractional distillation ✗, desalination ✗
Mark scheme
23Oct / Nov 2019 · Paper 11 · Q31Show mark scheme →
Afine sand
Bharmful microbes
Cmineral salts
Dsolid organic matter
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24May / June 2019 · Paper 11 · Q32Show mark scheme →
Aadding chlorine
Bdistillation
Cfiltering
Dpassing through carbon
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25May / June 2019 · Paper 12 · Q32Show mark scheme →
Aadding carbon
Bchlorination
Cdesalination
Dfiltration
Mark scheme
26Oct / Nov 2018 · Paper 11 · Q33Show mark scheme →
Ametal compounds
Bnitrate fertilisers
Coxygen
Dsulfuric acid
Mark scheme
27Oct / Nov 2018 · Paper 12 · Q33Show mark scheme →
Afiltration: harmful microbes; use of carbon: solids; chlorination: unpleasant odours and tastes
Bfiltration: harmful microbes; use of carbon: unpleasant odours and tastes; chlorination: solids
Cfiltration: solids; use of carbon: harmful microbes; chlorination: unpleasant odours and tastes
Dfiltration: solids; use of carbon: unpleasant odours and tastes; chlorination: harmful microbes
Mark scheme
28May / June 2018 · Paper 11 · Q35Show mark scheme →
Achlorination
Bdesalination
Cfiltration
Dneutralisation
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29May / June 2018 · Paper 12 · Q35Show mark scheme →
Adetergent
Bfertiliser
Csewage
Dsodium chloride
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30Oct / Nov 2017 · Paper 11 · Q34Show mark scheme →
Abad odours
Bharmful bacteria
Csodium chloride
Dsolid particles
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31Oct / Nov 2017 · Paper 12 · Q35Show mark scheme →
AChlorine is used to desalinate the water.
BChlorine kills bacteria that may be present in the water.
CChlorine precipitates solids that may be present in the water.
DChlorine removes tastes and odours from the water.
Mark scheme
32May / June 2017 · Paper 12 · Q32Show mark scheme →
A1
B2
C3
D4
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33Oct / Nov 2016 · Paper 11 · Q32Show mark scheme →
Achlorination — removes tastes
Bdesalination — removes solids
Cfiltration — removes salt
Duse of carbon — removes odours
Mark scheme
34May / June 2016 · Paper 11 · Q32Show mark scheme →
Aacid rain
Bcarbon monoxide
Cfertiliser
Dmetal compounds
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35May / June 2016 · Paper 12 · Q32Show mark scheme →
Acarbonate
Bchloride
Cnitrate
Dsulfate
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