Introduction
What happens to air composition in a closed space? This PSLE Science Air Composition Lift Question tests your understanding of breathing, air composition, and water vapour changes.
In this PSLE Science Air Composition Lift Question, students must analyse what happens to nitrogen and water vapour when people are trapped in a lift with no fresh air entering.
The Question
Some people were trapped in a lift where air could not enter or escape.
Which best describes the amount of:
- Nitrogen
- Water vapour
after 1 hour?
Step-By-Step Explanation (Teacher Working)
Step 1 — Understand Closed System
No air enters
No air leaves
Only breathing changes gas composition.
Step 2 — What Happens During Breathing?
People:
- Take in Oxygen
- Release Carbon Dioxide
- Release Water Vapour
Step 3 — Nitrogen Behaviour
Nitrogen is NOT used by the body.
Nitrogen is NOT produced by breathing.
✅ Nitrogen = No Change
Step 4 — Water Vapour Behaviour
Breathing releases moisture.
More people breathing → More water vapour.
✅ Water Vapour = Increase
Final Answer
Nitrogen → No Change
Water Vapour → Increase
✔ Correct Option = Option 2
Key Concepts
Air Composition
Air contains:
- Nitrogen ~78%
- Oxygen ~21%
- Carbon dioxide (very small amount)
- Water vapour (variable)
Breathing Effects
Breathing changes:
- Oxygen decreases
- Carbon dioxide increases
- Water vapour increases
- Nitrogen stays same
Tips for Students
✔ Nitrogen almost never changes in breathing questions
✔ Oxygen usually decreases
✔ Carbon dioxide usually increases
✔ Water vapour usually increases
For Parents
This topic develops:
- Logical reasoning
- Data interpretation
- Real-life science application
Air composition questions appear frequently in PSLE exams.
Conclusion
This PSLE Science Air Composition Lift Question tests real understanding of breathing and air composition.
Always remember:
- Nitrogen usually stays constant
- Water vapour increases when people breathe in enclosed spaces
Mastering this PSLE Science Air Composition Lift Question helps students score confidently in PSLE Science exams.