Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want the Air and Water basic worksheet topics — composition, treatment and pollution — to become reliable marks instead of disconnected facts about gases and water.
What query it owns: how to understand and revise the Air and Water basic worksheet in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the air-and-water-worksheet-basic revision-guide angle, while Tutopiya’s Air and Water Worksheet (Basic) subtopic page owns the learning resource and the free Air and Water Worksheet quiz owns the practice.

The Air and Water basic worksheet in Cambridge IGCSE Coordinated Science (0654) pulls together foundation ideas from both subtopics: air composition, uses of atmospheric gases, water as a solvent, water treatment and pollution. Examiners test these as short structured questions that reward precise definitions and ordered processes. This guide maps every core idea the worksheet covers and shows how to turn them into full-mark answers.

Key takeaways

• Clean dry air is approximately 78% nitrogen, 21% oxygen and 1% argon (plus trace gases).
• Fractional distillation of liquid air separates nitrogen, oxygen and argon by boiling point.
• Potable water is safe to drink — produced by filtration, sedimentation and chlorination.
• Water pollution sources include sewage, fertilisers and industrial waste.
• Tests for water: anhydrous copper(II) sulfate turns blue (water present); cobalt(II) chloride paper turns pink.

What does the Air and Water basic worksheet cover in Cambridge IGCSE Coordinated Science?

The basic worksheet consolidates the Air and Water unit into exam-style questions on composition, separation, uses, treatment and pollution. You need to state percentages, describe industrial processes step by step, name tests for water, and explain how pollutants enter and harm ecosystems. Working through the worksheet after revising each subtopic is the fastest way to find gaps before the exam.

Start with Tutopiya’s Air and Water Worksheet (Basic) subtopic page for the full question set and model answers.

The core ideas you must master

Topic area	Key fact / process	Typical worksheet question
Air composition	78% N₂, 21% O₂, 1% Ar	”State the percentage of oxygen in air.”
Fractional distillation	Separate liquid air by boiling point	”Describe how oxygen is obtained from air.”
Uses of gases	N₂ inert; O₂ combustion; Ar in lamps	”Give a use of nitrogen.”
Water treatment	Filter → sediment → chlorinate	”Describe how potable water is made.”
Water tests	CuSO₄ white → blue; CoCl₂ blue → pink	”Name a test for water.”
Pollution	Sewage, fertilisers, industrial waste	”State a source of water pollution.”

Air — composition and separation

Gas	Percentage in clean dry air	Property	Industrial use
Nitrogen	~78%	Unreactive	Food packaging, ammonia manufacture
Oxygen	~21%	Supports combustion	Steelmaking, hospitals, welding
Argon	~1%	Inert noble gas	Light bulbs, welding shield gas

Fractional distillation of liquid air: filter and compress air → cool to liquid → distil in a fractionating column → nitrogen boils off first (lower b.p.) → oxygen collected at higher temperature → argon separated last.

Water — treatment and tests

Stage	What happens	Purpose
Screening / filtration	Remove large solids	Clear visible debris
Sedimentation	Solids settle to bottom	Remove suspended particles
Filtration (sand/gravel)	Fine particles trapped	Further purification
Chlorination	Chlorine added	Kill harmful bacteria
Fluoridation (optional)	Fluoride added	Dental health

Tests for water: anhydrous copper(II) sulfate (white → blue); cobalt(II) chloride paper (blue → pink).

Worksheet topics in past-paper wording

Command word	What the question wants	Typical stem
State	Percentage, name or fact	”State the percentage of nitrogen in air.”
Describe	Ordered process	”Describe how potable water is produced.”
Explain	Cause and effect	”Explain why chlorine is added to water.”
Give	Named example	”Give a use of oxygen.”
Suggest	Apply to scenario	”Suggest a source of water pollution.”

Worked exam-style stems

1. “Describe how oxygen is obtained from the air on an industrial scale.” Air filtered and compressed → cooled until liquid → fractional distillation → nitrogen boils off first → oxygen collected at higher temperature. Reward: liquid air + boiling point difference + oxygen collected separately.
2. “Describe how river water is made safe to drink.” Filter to remove solids → sedimentation → further filtration → chlorination to kill bacteria. Reward: at least three named stages in order.
3. “Explain why nitrogen is used to pack food.” Nitrogen is unreactive — it prevents oxidation and slows decay by excluding oxygen. Reward: unreactive + excludes oxygen + preserves food.

Practise on the Air and Water Worksheet quiz.

How the Air and Water worksheet connects to the syllabus

The worksheet draws on Air, Water, Carbon Dioxide and Methane and Nitrogen and Fertilisers. The Cambridge IGCSE Coordinated Science resource hub links every subtopic.

Common mistakes students make

• Stating air is 50% oxygen (correct answer is 21%).
• Confusing filtration with fractional distillation (water vs air).
• Saying chlorination removes solids (it kills bacteria).
• Forgetting the colour change direction in water tests (white CuSO₄ → blue).
• Listing pollution sources without linking to eutrophication or disease.

When you need more support

If Air and Water worksheet questions keep costing marks, work through the Air and Water Worksheet quiz, then get help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

What is potable water? Water that is safe to drink, produced by filtering and treating raw water to remove solids and kill harmful microorganisms.

How is oxygen separated from air industrially? By fractional distillation of liquid air — gases are separated according to their different boiling points.

What test shows that water is present? Anhydrous copper(II) sulfate turns from white to blue, or cobalt(II) chloride paper turns from blue to pink.

How do I use the Air and Water basic worksheet effectively? Revise each subtopic first, attempt the worksheet questions under timed conditions, check answers, then take the quiz.

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