Q11: Scientists examined diamonds that were formed

LR Question 11 Explanation

QUESTION TEXT: Scientists examined diamonds that were formed on Earth…

QUESTION TYPE: Most Strongly Supported

FACTS: Some diamonds formed in a certain way. This could only have happened if the earth’s atmosphere didn’t have much oxygen.

ANALYSIS: Don’t let this question’s scientific language fool you. It’s very straightforward. I intentionally simplified it in my summary.

The diamonds formed due to a chemical reaction. The reaction couldn’t have happened if there was much oxygen in the atmosphere.

O ➞ R (evidence)

R ➞ O (contrapositive)

Therefore, since the reaction did happen, there wasn’t much oxygen in the atmosphere.

___________

We have no clue when most diamonds of this type were formed. Maybe most were formed 1.5 billion years ago. The atmosphere might have stayed low oxygen for quite a while.
We have no idea how the chemical reactions worked. But since they couldn’t have happened if there was much oxygen, they probably didn’t involve oxygen.
CORRECT. See the last sentence . If the atmosphere had contained oxygen, then the reactions wouldn’t have happened and the diamonds wouldn’t have formed.
Read the second sentence. These diamonds have a higher than normal concentration of sulfur-33. That doesn’t mean modern diamonds have none.
Not quite. The stimulus is talking about the formation of diamonds high in sulfur-33. We have no idea how normal diamonds form.