PT105.S2.Q16 > Question

SECTION 1 · lr

Question 1 Question 2 Question 3 Question 4 Question 5 Question 6 Question 7 Question 8 Question 9 Question 10 Question 11 Question 12 Question 13 Question 14 Question 15 Question 16 Question 17 Question 18 Question 19 Question 20 Question 21 Question 22 Question 23 Question 24 Question 25 Question 26

SECTION 2 · lr

SECTION 3 · rc

PASSAGE 1

Question 1 Question 2 Question 3 Question 4 Question 5 Question 6 Question 7

PASSAGE 2

Question 8 Question 9 Question 10 Question 11 Question 12 Question 13 Question 14

PASSAGE 3

Question 15 Question 16 Question 17 Question 18 Question 19 Question 20 Question 21

PASSAGE 4

Question 22 Question 23 Question 24 Question 25 Question 26

SECTION 4 · lr

The author concludes that a star lacking lithium cannot be one of the coolest brown dwarfs. This is because those brown dwarfs are the only kinds of stars that can be cool enough to retain some of their lithium.

The support establishes that all stars except the coolest brown dwarfs destroy their lithium, but fails to establish that the coolest brown dwarfs do not ever destroy their lithium. If the coolest brown dwarfs sometimes rid themselves of lithium, then a star lacking lithium could still be one of the coolest brown dwarfs.

The argument depends on the assumption that the coolest brown dwarfs do not ever destroy, or otherwise eliminate, their lithium.

This must be true in order for the conclusion to follow. If even a few of the coolest brown dwarfs are hot enough to destroy lithium, then a lithium-free star could still be one of them—undermining the claim that no lithium means the star can’t be one of the coolest brown dwarfs.

Irrelevant. The conclusion is only concerned with what a lack of lithium indicates about a star. There’s no need to assume any correlation with a star’s inability to burn hydrogen.

The conclusion is simply that a lack of lithium proves that any given star is not one of the coolest brown dwarfs. It’s irrelevant whether these dwarfs burn helium or not.

Since the conclusion is only concerned with stars once they have already burned all of their lithium, the amount of lithium that they started out with is irrelevant.

The lithium content of a star is what matters; its appearance is irrelevant. The author claims that a lack of lithium proves that a star is not one of the coolest brown dwarfs.

PrepTest 105 - Section 2 - Question 16

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