Question detail
Which gas makes up about 20 percent of 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. Nitrogen
- B. Oxygen
- C. Carbon Dioxide
- D. Argon
Answer
The correct option is Oxygen. This answer is correct because it matches the approved learning objective to recall that the Earth's atmosphere is about 80 percent nitrogen in the subtopic The proportions of different gases in the atmosphere.
Explanation
The correct option is Oxygen. Oxygen is correct because it directly supports the approved learning objective to recall that the Earth's atmosphere is about 80 percent nitrogen. This belongs to the subtopic The proportions of different gases in the atmosphere 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 The proportions of different gases in the atmosphere.
Common mistake
Nitrogen Proportion Confusion
Students often confuse the proportion of nitrogen in the Earth's atmosphere with that of oxygen, thinking it is around 20 percent instead of 80 percent.
To fix this, students should remember that nitrogen makes up the majority of the atmosphere at about 80 percent, while oxygen is around 20 percent.
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