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Composition of the Atmosphere Practice Questions | Year 8 UK Science
🌍 Composition of the Atmosphere
50 Practice Questions – Year 8 UK Science
📝 Multiple Choice Questions (1–15)
1. Which gas is present in the highest percentage in air?
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✅ Nitrogen (about 78%)
2. Oxygen makes up approximately:
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✅ 21%
3. Which gas supports combustion?
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✅ Oxygen
4. Which gas is used by plants in photosynthesis?
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✅ Carbon dioxide
5. Which gas is a noble gas?
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✅ Argon
6. Which gas prevents air from being too reactive?
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✅ Nitrogen
7. Which gas is present in variable amounts?
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✅ Water vapour
8. Which gas is needed for breathing?
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✅ Oxygen
9. Which gas has the smallest percentage?
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✅ Carbon dioxide
10. Dry air does NOT include:
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✅ Water vapour
11. Which gas helps keep Earth warm?
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✅ Carbon dioxide
12. Which gas does NOT support burning?
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✅ Both nitrogen and carbon dioxide
13. Which gas is most abundant?
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✅ Nitrogen
14. Which gas is unreactive?
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✅ Argon
15. Which gas is essential for life?
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✅ Oxygen
✔ True or False (16–25)
16. Nitrogen supports respiration.
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❌ False – Oxygen supports respiration.
17. Oxygen makes up about one fifth of air.
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✅ True
18. Argon is highly reactive.
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❌ False – Argon is inert.
19. Carbon dioxide is a greenhouse gas.
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✅ True
20. Water vapour amount is constant.
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❌ False – It varies.
21. The atmosphere protects Earth.
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✅ True
22. Plants need oxygen for photosynthesis.
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❌ False – They use carbon dioxide.
23. Dry air contains water vapour.
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❌ False
24. Nitrogen helps dilute oxygen.
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✅ True
25. Trace gases are present in large amounts.
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❌ False
✏ Fill in the Blanks (26–35)
26. The atmosphere is held by __________.
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✅ Gravity
27. __________ gas makes up about 78% of air.
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✅ Nitrogen
28. Oxygen percentage is approximately __________%.
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✅ 21%
29. __________ gas is used by plants.
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✅ Carbon dioxide
30. __________ is a noble gas.
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✅ Argon
31. Carbon dioxide is present in __________ amounts.
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✅ Small
32. Water vapour helps form __________.
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✅ Clouds / rain
33. Oxygen supports __________.
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✅ Respiration / burning
34. Nitrogen is mostly __________.
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✅ Unreactive
35. The atmosphere protects us from harmful __________.
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✅ Radiation
📌 Short & Long Answer Questions (36–50)
36. What is the atmosphere?
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The atmosphere is a layer of gases surrounding the Earth.
37. Name two gases in air.
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Nitrogen and oxygen.
38. Why is oxygen important?
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It is needed for respiration and releasing energy from food.
39. Why is nitrogen important?
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It reduces reactivity and helps plant growth.
40. What is dry air?
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Air without water vapour.
41. Name one greenhouse gas.
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Carbon dioxide.
42. What are trace gases?
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Gases present in very small amounts.
43. Why is argon unreactive?
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It is a noble gas.
44. One function of water vapour.
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Forms clouds and rain.
45. How does the atmosphere protect Earth?
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Blocks harmful radiation and controls temperature.
46–50. Explain composition, importance of gases, CO₂, water vapour, and life support.
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Nitrogen 78%, Oxygen 21%, Argon 0.9%, Carbon dioxide 0.04%.
Atmosphere supports life, weather, and protection.