LSAT 137 – Section 2 – Question 11

LSAT 137 - Section 2 - Question 11

October 2012

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT137 S2 Q11
+LR
Most strongly supported +MSS
Conditional Reasoning +CondR
Causal Reasoning +CausR
A
2%
153
B
3%
153
C
93%
164
D
1%
153
E
1%
150
136
143
150
 +Medium 146.731 +SubsectionMedium

Scientists examined diamonds that were formed on Earth about 2.9 billion years ago. These diamonds had a higher-than-normal concentration of sulfur-33. This concentration can be explained only by certain chemical reactions that are stimulated by ultraviolet light. If there had been more than a trace of oxygen in Earth’s atmosphere 2.9 billion years ago, then not enough ultraviolet light would have reached Earth’s surface to stimulate the chemical reactions.

Summary
Scientists examined diamonds formed 2.9 billion years ago and concluded these diamonds had higher-than-normal concentrations of sulfur-33. The only way this concentration occurs is from a chemical reaction triggered by ultraviolet light. If there was more than a trace of oxygen in the atmosphere 2.9 billion years ago, then not enough ultraviolet light would be present to cause the chemical reaction.

Strongly Supported Conclusions
2.9 billion years ago the atmosphere had at most very little oxygen.

A
Most diamonds with higher-than-normal concentrations of sulfur-33 were formed at least 2.9 billion years ago.
This answer is unsupported. We don’t know if this is true of most diamonds with this concentration. We only know from the stimulus that there are at least a few of them formed 2.9 billion years ago.
B
Ultraviolet light causes the oxygen in Earth’s atmosphere to react chemically with sulfur-33.
This answer is unsupported. We don’t know whether the oxygen is specifically reacting with sulfur-33. We only know from the stimulus that a “certain chemical reaction” occurs when stimulated by ultraviolet light.
C
Earth’s atmosphere contained very little, if any, oxygen 2.9 billion years ago.
This answer is strongly supported. This answer explains why the diamonds in the stimulus have higher than normal concentrations of sulfur-33.
D
Sulfur-33 is rarely found in diamonds that were formed more recently than 2.9 billion years ago.
This answer is unsupported. We don’t know anything about more recently formed diamonds from the stimulus. The stimulus is strictly limited to the diamonds scientists are examining from 2.9 billion years ago.
E
The formation of diamonds occurs only in the presence of ultraviolet light.
This answer is unsupported. We don’t know from the stimulus under what conditions diamonds are formed generally.

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LSAT PrepTest 137 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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