PT146.S2.Q18

PrepTest 146 - Section 2 - Question 18

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The consensus among astronomers, based upon observations of the surfaces of pulsars, is that pulsars are spinning balls of neutrons compressed into a sphere some 10 kilometers in diameter with a mass roughly equal to that of our sun. However, their observed properties are also consistent with some pulsars actually being filled with quarks, the building blocks of neutrons. Because the core of a quark-filled pulsar, unlike a neutron-filled one, would have an overall positive charge, it would attract a layer of negatively charged particles that could support a crust of neutrons.

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18.

The statement that the core of a quark-filled pulsar would have an overall positive charge plays which one of the following roles in the argument above?

a

It helps explain how pulsars could have neutrons on their surface even if they were not entirely made up of neutrons.

The statement in the question stem provides information that helps explain how the author’s conclusion that pulsars are filled with quarks is consistent with the observation that pulsars have neutrons on their surface.

77%
b

It forms part of a challenge to the claim that some pulsars may be made up of quarks.

The statement in the question stem helps support the conclusion that pulsars may be made of quarks; it does not challenge this claim.

3%
c

It helps explain why some pulsars would not be readily recognized as such by astronomers.

The argument does not discuss what astronomers can readily recognize. We do not know if astronomers have difficulty recognizing pulsars; the argument is concerned with the composition of pulsars.

3%
d

It presents a new finding that challenges the consensus view of the structure of pulsars.

The claim in the question stem does open an alternative to the consensus view, but we cannot say that it is a new finding.

15%
e

It points out a problem with the view that pulsars have a mass roughly equal to that of our sun.

The information in the question stem does not challenge the claim about the mass of pulsars.

1%

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