PT113.S1.P2.Q13 > Analytics

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Spurred by the discovery that a substance containing uranium emitted radiation, Marie Curie began studying radioactivity in 1897. ███ █████ ██████ ████ ███ ██████ ███ █████████ ███ █████ █████ ███ ████ ██████ ████████████ █ ███████ ████ ███ █████ ██ ███████ ████████ ███ ██████████ ████ ██ ███ ████ ███████████ ████ ████████ ██████ ██ ███ ██████████ ████ ███████████ ████ ███████ ██ █████ ███ █████ ███████████ ████████ █████ ███ ████ ██ ███████ █ ████ ██ ██████████ ███████ █████████ ████████ ███ ███████ ███████ ███ █████████ ██ ███ ████ ██ ███████████ █████████ ███ ██████████ ████ ███████ ███████ █████████ ██ █ ██████████ █████ ████ ██ ██████ ██ ██████████ █████ ██ █████ ████████ █████ █████████ ████ ███ ████████ ████ ███ █ █████ ███████ ███ █████████ ████████████ ███████ █████████ ████████ ██ ██ ████████████ ████ ██ ███████████ ██████████ ███████ █████████ ███ ████████████ █████████ ███ ███ ██████ ██ █████████ █ █████████ ██ █████ ██ ███████ ██████████

Intro topic · Marie Curie's discoveries related to radiation

Discovered polonium and radium. Also disocvered that uranium emitted radiation at a constant rate. But, she couldn't explain what causes raidation.

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Critics and response · Some fault Curie for not discovering cause of radiation and decreasing rate; author says it wasn't her fault

Curie didn't have the evidence that we have today.

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Support for author's response · Various radioactive isotopes weren't available to Curie or decayed to slowly to learn anything about rate

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Additional support · Nature of atom was being debated during Curie's time

Physicists (like Curie) believed that matter couldn't be divided indefinitely. In other words, there's nothing smalling than the atom.

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Continuing prior support · Curie couldn't have realized that atoms lose mass

Praise for Curie · Curie's research helped later breakthroughs

Passage Style

Critique or debate

Spotlight

13.

Which one of the following ████ ██████████ █████████ ███ ███████ ██ ███ ████ ███████████ ██ ████ ██ ███ ██████ ██ ███ ████ ████████ ██ ███ █████ ██████████

Question Type

Meaning in context (of word, phrase, or idea)

Structure

To understand the meaning of “mechanism,” we need to understand what Curie failed to do. As explained in the last paragraph, Curie was not able to explain how radiation occurs. Ultimately quantum mechanics helped show that radiation occurs “because the atoms themselves lose mass.” This causal explanation of radiation is the “mechanism” Curie failed to identify. So “mechanism” refers to a cause of something.

the physical process ████ █████████ █ ██████████

This best captures the meaning of “mechanism” as used in the last sentence of P1. Curie failed to identify the physical process that explains why radiation occurs.

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the experimental apparatus ██ █████ █ ██████████ ██████

There’s no reason to think “mechanism” refers to an experimental apparatus. It doesn’t make sense for Curie to have been unable to “postulate” an experimental apparatus. She would have been able to describe the experimental tools she used.

the procedure scientists ███ ██ █████ █████ ███ ██████████ ██ █ ██████████

It doesn’t make sense for Curie to have been unable to “postulate” the procedure she used to bring about radiation. She would have been able to describe her experiment and what she did. What she didn’t understand was the exact physical process that was occurring when an element exhibited radiation.

the isotopes of ██ ███████ ██████ ██ ███████ █ ██████████

Curie didn’t know about isotopes. So it wouldn’t make sense for the author to write that Curie couldn’t “postulate” an isotope to explain radiation. She would have had no reason to think of radiation in terms of isotopes.

the scientific theory ██████████ █ ██████████

The thing Curie was unable to postulate was a causal explanation for why/how radiation occurs. But it’s not clear that she was unable to “describe” radiation. She did describe certain aspects of radiation — she described the rate of emitting radiation and described different levels of radiation in different elements. What was missing was how radiation occurred, not just a description of radiation. In addition, it’s not clear that the causal mechanisms discussed later in the passage (isotopes decaying, atoms losing mass) are a “scientific theory.” So that’s another reason “mechanism” doesn’t properly refer to “scientific theory.”

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PrepTest 113 - Section 1 - Passage 2 - Question 13

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