IGCSE · Chemistry 0620 · Chemistry of the environment

Water: IGCSE Chemistry questions with answers

Free Water 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.

Generate a full Water worksheet →All Chemistry of the environment questions

Water practice questions

Question 1Multiple choice · 1 markA* challenge

Water from a river is treated to make it safe to drink.
1    Chlorine is added to kill bacteria.
2    Chlorination makes the water pure.
3    Filtration removes insoluble solids.
Which statements are correct?

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

Answer: B

Question 2Multiple choice · 1 markA* challenge

A student tests a colourless liquid to find out whether it is pure water.
1    If it turns blue cobalt(II) chloride pink, it must be pure water.
2    Pure water freezes at exactly 0 °C.
3    If it contains water, it turns white anhydrous copper(II) sulfate blue.
Which statements are correct?

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

Answer: B

Question 3Multiple choice · 1 mark

Which statement describes chlorination?

  1. A Pure water boils at 100 °C and melts at 0 °C
  2. B Metals with high densities and melting points that form coloured compounds and act as catalysts
  3. C The addition of chlorine to the water supply to kill microbes
  4. D The Group VII elements, diatomic non-metals whose reactivity decreases down the group
Show answer

Answer: C

Question 4Multiple choice · 1 markA* challenge

Water from a river is treated to make it safe to drink.
1    Filtration removes insoluble solids.
2    Chlorine is added to kill bacteria.
3    Chlorination makes the water pure.
Which statements are correct?

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

Answer: B

Question 5Structured · 6 marks

Water from rivers is treated before it is supplied to homes.

(a)

Describe the purpose of filtration and chlorination in water treatment.

[2]
(b)

Describe a chemical test for water and give the result.

[2]
(c)

Describe a physical test to show that a sample is pure water.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)remove solids; kill microbes
filtration removes insoluble solids B1
chlorination kills bacteria/microbes B1
2
(b)anhydrous copper sulfate white → blue
add anhydrous copper(II) sulfate B1
turns from white to blue (or cobalt chloride paper blue to pink) B1
2
(c)boils at 100 °C, melts at 0 °C
boiling point exactly 100 °C B1
melting point exactly 0 °C B1
2
Question 6Structured · 3 marks

Desalination produces drinking water from sea water.

(a)

Name a method of desalination.

[1]
(b)

Explain why desalination is expensive.

[1]
(c)

State why sea water is not suitable for drinking.

[1]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)distillation / reverse osmosis
distillation (or reverse osmosis) B1
1
(b)large energy needed
it needs a lot of energy (to boil water/high pressure) B1
1
(c)too much salt
high salt concentration (dehydrates the body) B1
1

More Chemistry of the environment questions

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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