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CAIE IGCSE Chemistry 10.1 Water Question Bank

Practise water chemistry by linking tests, purity checks, natural impurities and domestic treatment steps to exam observations.

Syllabus
2026–2028
Course
Chemistry 0620

Exam points

  • interpret colour changes for anhydrous cobalt(II) chloride and copper(II) sulfate
  • use boiling point or freezing point evidence to decide whether a water sample is pure
  • match filtration, carbon and chlorination to their roles in domestic water treatment

Covered syllabus points

10.1.1—Chemical tests for the presence of10.1.2—To test for the purity of water using10.1.3—Distilled water is used in practical10.1.4—Substances found in natural water10.1.5—Some of these substances are10.1.6—Harmful substances: toxic metal10.1.7—Treatment of the domestic water supply

10.1 Water question 1

[Maximum number: 2]

Cobalt and copper are transition elements.

Both copper and cobalt can form coloured compounds. Some of these compounds contain water of crystallisation.

State the colour change seen when a few drops of water are added to anhydrous copper(II) sulfate.
from to

10.1 Water question 2

[Maximum number: 5]

Question (a)

(a)

Filtration and chlorination are two stages in water treatment.
State the purpose of each stage.
filtration
chlorination

[ 2 ]

Question (b)

(b)

A student uses anhydrous copper(II) sulfate to test for the presence of water.

[ 3 ]

Question (i)

(i)

What colour change is seen if water is present?
from to

[ 2 ]

Question (ii)

(ii)

The purity of a sample of water can be assessed by measuring its boiling point.

How is the boiling point of water affected by impurities?

[ 1 ]

10.1 Water question 3

[Maximum number: 1]

Some substances found in water extracted from a river are listed.

1 plastics
2 nitrates
3 oxygen

Which substances are harmful to aquatic life?

A

1 and 2

B

1 and 3

C

2 only

D

3 only

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