CO2 percent in air about
- 0.04%
- 21%
- 78%
- 50%
Show answer and explanation
Answer: A. 0.04%
about 0.04%.
O Level Chemistry: Air, water and the environment, questions with answers
Practise 40 real questions on Air, water and the environment from 2021 to 2026. See the answer and explanation as soon as you answer.
40real questions
27multiple choice
11exam sessions
About Air, water and the environment in O Level Chemistry
Air, water and the environment is one of the 12 main topics in our O Level Chemistry (Cambridge (CAIE) 5070) question bank, and about 6% of its real questions come from it. Tayyari Karo has 40 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2; 27 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 36 medium, 4 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 6 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
Carbon dioxide, methane and oxygen are gases involved in the carbon cycle. Which of these gases cause global warming?
- carbon dioxide only
- carbon dioxide and methane
- carbon dioxide and oxygen
- methane only
Show answer and explanation
Answer: B. carbon dioxide and methane
Carbon dioxide and methane are both greenhouse gases that trap heat in the atmosphere, whereas oxygen is not a greenhouse gas.
Hardness removed by
- boiling (temporary) / ion exchange
- adding salt
- adding CO2
- filtering sand
Show answer and explanation
Answer: A. boiling (temporary) / ion exchange
Boiling/ion exchange.
Oxygen in air is about
- 78%
- 21%
- 1%
- 0.04%
Show answer and explanation
Answer: B. 21%
about 21%.
Nitrogen from air is used to
- breathe
- make ammonia (Haber)
- cause acid rain
- burn
Show answer and explanation
Answer: B. make ammonia (Haber)
N₂ + H₂ → NH₃.
About ethanol from sugar cane: 1 non-renewable; 2 grows removing CO₂. Which?
- 1 only
- 2 only
- both
- neither
Show answer and explanation
Answer: B. 2 only
Sugar cane is renewable and removes CO₂ while growing.
Sessions with Air, water and the environment questions
| Session | Paper 1 | Paper 2 |
|---|---|---|
| May/June 2026 | 1 | – |
| May/June 2025 | 3 | 1 |
| Oct/Nov 2025 | 2 | 1 |
| May/June 2024 | 2 | 1 |
| Oct/Nov 2024 | 3 | – |
| May/June 2023 | 3 | 2 |
| Oct/Nov 2023 | 3 | – |
| May/June 2022 | 2 | 2 |
| Oct/Nov 2022 | 3 | 3 |
| May/June 2021 | 2 | 1 |
| Oct/Nov 2021 | 3 | 2 |
Common questions
What does the Air, water and the environment topic cover on this page?
40 real O Level Chemistry (5070) questions on Air, water and the environment from 2021 to 2026, from Paper 1, Paper 2. Each one shows the year, session and paper it came from.
Do I get the answers and explanations?
Yes. Every question shows the correct answer and a short explanation the moment you answer.
Is it free?
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks every paper, the full question bank and the paper PDFs.