Skill 2 of 2 · Reading for Meaning in ScienceClose
Science vocabulary, terms, and phrases
Understand science passages, symbols, terms, and formulas, and explain them in scientific words.
You do not need to memorize every term — read what the passage tells you.
In CO₂ + H₂O → H₂CO₃, the + means substances combine and the → means a new substance forms.
Know the difference between a hypothesis, a theory, and a scientific law.
Question 1 of 4
About 2.7 billion years ago the lower atmosphere had almost no oxygen. In the upper atmosphere, oxygen can be produced when carbon dioxide is split by sunlight. Scientists examined 11 ancient micrometeorites older than 2.7 billion years and found most had been iron particles mixed with oxygen, meaning the upper atmosphere held nearly as much oxygen as it does now. The scientists say the new information does not change what is known about the lower atmosphere.
Which statement accurately summarizes the passage?