The Earth’s magnetic field is generated as the molten iron of the Eart

Question

The Earth’s magnetic field is generated as the molten iron of the Earth’s outer core revolves around its solid inner core. When surges in the molten iron occur, magnetic tempests are created. At the Earth’s surface, these tempests can be detected by changes in the strength of the Earth’s magnetic field. For reasons not fully understood, the field itself reverses periodically every million years or so. During the past million years, for instance, the magnetic north pole has migrated between the Antarctic and the Arctic. Clearly, geophysicists who seek to explain and forecast changes in the field must understand what happens in the outer core. Unlike meteorologists, however, they cannot rely on observations made in their own lifetimes. Whereas atmospheric storms arise in a matter of hours and last for days, magnetic tempests develop over decades and persist for centuries. Fortunately scientists have been recording changes in the Earth’s magnetic field for more than 300 years.    1 
 1. In the passage, the author is primarily concerned with

(A) analyzing a complicated scientific phenomenon and its impact on the Earth’s surface features
(B) describing a natural phenomenon and the challenges its study presents to researchers
(C) discussing a scientific field of research and the gaps in researchers’ methodological approaches to it
(D) comparing two distinct fields of physical science and the different research methods employed in each
(E) proposing an explanation for a geophysical phenomenon and an experiment that could help confirm that explanation

2 
 2. The passage suggests which of the following about surges in the Earth’s outer core?

(A) They occur cyclically every few decades.
(B) They can be predicted by changes in the Earth’s inner core.
(C) They are detected through indirect means.
(D) They are linked to disturbances in the Earth’s atmosphere.
(E) They last for periods of about 1 million years.

3 
 3. It can be inferred from the passage that geophysicists seeking to explain magnetic tempests ought to conduct research on the Earth’s outer core because the Earth’s outer core

(A) is more fully understood than the Earth’s magnetic field
(B) is more easily observed than the Earth’s magnetic field
(C) has been the subject of extensive scientific observation for 300 years
(D) is involved in generating the Earth’s magnetic field
(E) reflects changes in the inner core caused by magnetic tempests

4 
 4. In the second paragraph, the author is primarily concerned with

(A) stating a limitation that helps determine a research methodology
(B) making a comparative analysis of two different research methodologies
(C) assessing the amount of empirical data in the field of physical science
(D) suggesting an optimistic way of viewing a widely feared phenomenon
(E) describing a fundamental issue and discussing its future impact on society

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 149 Date: 15-Apr-2021
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Ruby2021 · Answer

Hi could someone please explain Q2 & Q3? Thanks.

Akshay J · Answer

My answers:
1. B
2. C
3. D
4. D

Request the moderator to give out the answers for this.

Rohitq · Answer

Q3:
(A) is more fully understood than the Earth’s magnetic field -->  (The passage talks about the phenomenon magnetic tempests and no where a comparison is made on the outer core and magnetic field) 
(B) is more easily observed than the Earth’s magnetic field---->  ( Again we do not know this for sure since the passage did not talk of doing a research on magnetic field and outer core.) 
(C) has been the subject of extensive scientific observation for 300 years---> ( This is a fact stated in the passage hence not an inference ) 
(D) is involved in generating the Earth’s magnetic field --->  Correct  , since we can see in first few lines that there is a correlation of out core and inner core in creating a magnetic field, which is true and we can infer that out core has a role in generating magnetic field)
(E) reflects changes in the inner core caused by magnetic tempests. (No mention in passage)

Cheers to learning!!

ankurgarg2410 · Answer

1. In the passage, the author is primarily concerned with

(A) analyzing a complicated scientific phenomenon and its impact on the Earth’s surface features
 (B) describing a natural phenomenon and the challenges its study presents to researchers  - Author starts with detailing the natural phenomenon (magnetic field generation and reversal) and ends with stating the challenge in its study (cannot be observed due to the long development and lasting periods of tempests, which are linked with the magnetic field).
(C) discussing a scientific field of research and the gaps in researchers’ methodological approaches to it
(D) comparing two distinct fields of physical science and the different research methods employed in each
(E) proposing an explanation for a geophysical phenomenon and an experiment that could help confirm that explanation

2. The passage suggests which of the following about surges in the Earth’s outer core?

(A) They occur cyclically every few decades.
(B) They can be predicted by changes in the Earth’s inner core.
 (C) They are detected through indirect means.  -  When surges in the molten iron occur, magnetic tempests are created. At the Earth’s surface, these tempests can be detected by changes in the strength of the Earth’s magnetic field.  Surges result in tempest, which in turn are detected indirectly. Hence, the correct answer.
(D) They are linked to disturbances in the Earth’s atmosphere.
(E) They last for periods of about 1 million years.

3. It can be inferred from the passage that geophysicists seeking to explain magnetic tempests ought to conduct research on the Earth’s outer core because the Earth’s outer core

(A) is more fully understood than the Earth’s magnetic field
(B) is more easily observed than the Earth’s magnetic field
(C) has been the subject of extensive scientific observation for 300 years
 (D) is involved in generating the Earth’s magnetic field  - This is inferred from this part of the passage:   The Earth’s magnetic field is generated as the molten iron of the Earth’s outer core  revolves around its solid inner core. When  surges in the molten iron occur, magnetic tempests are create d. At the Earth’s surface, these tempests can be detected by changes in the strength of the Earth’s magnetic field. 
(E) reflects changes in the inner core caused by magnetic tempests

4. In the second paragraph, the author is primarily concerned with

(A) stating a limitation that helps determine a research methodology  - Author states that the tempest cannot be studied by observations, since they develop over decades and last for centuries. This is the limitation of the observation methodology, which is easily done in another field (metrology)
(B) making a comparative analysis of two different research methodologies
(C) assessing the amount of empirical data in the field of physical science
(D) suggesting an optimistic way of viewing a widely feared phenomenon
(E) describing a fundamental issue and discussing its future impact on society

ashu2400 · Answer

Since its not been answered yet, I'll take a shot at it.

2. The passage suggests which of the following about surges in the Earth’s outer core?

Think it really boils down to A and C for me. So ill address just those.

(A) They occur cyclically every few decades.
What occurs every few decades? The line towards the end reads "magnetic tempests develop over decades and persist for centuries." The magnetic tempest may reform from a surge in the outer core say, ~500 years later - and this does not mean a surge every few decades, especially cyclically.
 
(C) They are detected through indirect means.
Can you detect a surge in the outer core through a change in magnetic field? The passage states "When surges in the molten iron occur, magnetic tempests are created. At the Earth’s surface, these tempests can be detected by changes in the strength of the Earth’s magnetic field." Detecting the magnetic field does in fact, qualify as an "indirect way" to detect a surge in the outer core since you're not  directly  measuring the surge through some instrument.

3. It can be inferred from the passage that geophysicists seeking to explain magnetic tempests ought to conduct research on the Earth’s outer core because the Earth’s outer core

This is an inference question - so we cannot hope to find it directly stated in the passage. Here we need to find a convincing reason to understand why the outer core in specific is studied to explain the occurrence of magnetic tempests. Here it boils down to C and D - so I will address those 2 options.

Note: this is a good trap if you've really understood the passage well. But again, if you go through the process of elimination, you will most likely not pick this. Just mentioning this because if you don't read the next option, you may end up picking this.

It's been mentioned "Fortunately scientists have been recording changes in the Earth’s magnetic field for more than 300 years." The magnetic fields do occur in the outer core. So yeah, this is a good reason IMO - you continue to study the outer core because it has been recorded for 3 centuries, and we've been told that its a process that needs to be studied over an extremely long period of time (multiple centuries). 
(D) is involved in generating the Earth’s magnetic field

This option is a no-brainer and is ultimately correct. It's been stated that the outer core has the presence of the magnetic tempests and hence, is the primary reason for studying it. Without this reason, there is no need to study the outer core to understand the magnetic tempests.

Navneet290 · Answer

Could someone please provide OA for Q4? Thankyou.

Sajjad1994 · Answer

Explanation

4. In the second paragraph, the author is primarily concerned with

Difficulty Level:   Hard

Explanation

In the second paragraph, the author discusses the difference between geophysics and meteorology in terms of the time scales involved. Geophysicists cannot rely on observations made in their own lifetimes because magnetic field changes happen over longer periods (decades to centuries) compared to meteorological phenomena (which develop over hours to days). This difference in time scales is a critical limitation that influences the research methodology of geophysicists. They must rely on recorded historical data, as stated in the text:  "Fortunately scientists have been recording changes in the Earth’s magnetic field for more than 300 years."

Option (A)  best captures the author's focus on stating a limitation that affects the research methodology in the field of geophysics.

Answer: A

The Earth’s magnetic field is generated as the molten iron of the Eart

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GMAT Reading Comprehension (RC) Questions

The Earth’s magnetic field is generated as the molten iron of the Eart

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