Question detail
What is the approximate percentage of oxygen in the Earth's atmosphere?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
The composition and evolution of the Earth's atmosphere
Question
- A. 20 percent
- B. 80 percent
- C. 50 percent
- D. 10 percent
Answer
The correct option is 20 percent. This answer is correct because it matches the approved learning objective to interpret simple evidence for changes in atmospheric oxygen over time in the subtopic How oxygen increased.
Explanation
The correct option is 20 percent. 20 percent is correct because it directly supports the approved learning objective to interpret simple evidence for changes in atmospheric oxygen over time. This belongs to the subtopic How oxygen increased within The composition and evolution of the Earth's atmosphere, so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from How oxygen increased.
Common mistake
Misinterpreting Evidence of Oxygen Changes
Students often confuse the evidence for changes in atmospheric oxygen with the causes of those changes.
Focus on interpreting specific data or evidence that shows how oxygen levels have changed over time, rather than explaining why those changes occurred.
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