Analysis of prehistoric air trapped in tiny bubbles beneath the polar

Question

Analysis of prehistoric air trapped in tiny bubbles beneath the polar ice sheets and of the composition of ice surrounding those bubbles suggests a correlation between carbon dioxide levels in the Earth’s atmosphere and global temperature over the last 160,000 years. Estimates of global temperature at the time air in the bubbles was trapped rely on measuring the relative abundances of hydrogen and its heavier isotope, deuterium, in the ice surrounding the bubbles. When global temperatures are relatively low, water containing deuterium tends to condense and precipitate before reaching the poles; thus, ice deposited at the poles when the global temperature was cooler contained relatively less deuterium than ice deposited at warmer global temperatures. Estimates of global temperature based on this information, combined with analysis of the carbon dioxide content of air trapped in ice deep beneath the polar surface, suggest that during periods of postglacial warming carbon dioxide in the Earth’s atmosphere increased by approximately 40 percent.   1 
 B 
 Q1. In the passage, the author is primarily concerned with doing which of the following?

(A) Describing a new method of estimating decreases in global temperature that have occurred over the last 160,000 years
(B) Describing a method of analysis that provides information regarding the relation between the carbon dioxide content of the Earth’s atmosphere and global temperature
(C) Presenting information that suggests that global temperature has increased over the last 160,000 years
(D) Describing the kinds of information that can be gleaned from a careful analysis of the contents of sheets
(E) Demonstrating the difficulty of arriving at a firm conclusion regarding how increases in the amount of carbon dioxide in the Earth’s atmosphere affect global temperature

2 
 B 
 Q2. It can be inferred from the passage that during periods of postglacial warming, which of the following occurred?

(A) The total volume of air trapped in bubbles beneath the polar ice sheets increased.
(B) The amount of deuterium in ice deposited at the poles increased.
(C) Carbon dioxide levels in the Earth atmosphere decreased.
(D) The amount of hydrogen in the Earth’s atmosphere decreased relatively the amount of deuterium.
(E) The rate at which ice was deposited at the poles increased.

3 
 C 
 Q3. The author states that there is evidence to support which of the following assertions?

(A) Estimates of global temperature that rely on measurements of deuterium in ice deposited at the poles are more reliable than those based on the amount of carbon dioxide contained in air bubbles beneath the polar surface.
(B) The amount of deuterium in the Earth’s atmosphere tends to increase as global temperature decreases.
(C) Periods of postglacial warming are characterized by the presence of increased levels of carbon dioxide in the Earth’s atmosphere.
(D) Increases in global temperature over the last 160,000 years are largely the result of increases in the ratio of deuterium to hydrogen in the Earth’s atmosphere.
(E) Increases in global temperature over the last 160,000 years have been accompanied by decreases in the amount of deuterium in the ice deposited at the poles.

4 
 C 
 Q4. It can be inferred from the passage that the conclusion stated in the last sentence would need to be reevaluated if scientists discovered that which of the following were true?

(A) The amount of deuterium in ice deposited on the polar surface is significantly greater than the amount of deuterium in ice located deep beneath the polar surface.
(B) Both the air bubbles trapped deep beneath the polar surface and the ice surrounding them contain relatively low levels of deuterium.
(C) Air bubbles trapped deep beneath the polar surface and containing relatively high levels of carbon dioxide are surrounded by ice that contained relatively low levels of deuterium.
(D) The current level of carbon dioxide in the Earth’s atmosphere exceeds the level of carbon dioxide in the prehistoric air trapped beneath the polar surface.
(E) Increases in the level of carbon dioxide in the Earth’s atmosphere are accompanied by increases in the amount of deuterium in the ice deposited at the poles.

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 136 Date: 06-Apr-2021
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kris19 · Answer

Q4. It can be inferred from the passage that the conclusion stated in the last sentence would need to be reevaluated if scientists discovered that which of the following were true?

I struggled with this question. The conclusion in the last sentence is 'during periods of postglacial warming, co2 increased by 40%'. When do we question this conclusion ?

In my first reading, I couldn't figure out that temp and co2 has positive correlation, so marked the wrong answer choice.
Once I found out that there is a positive correlation between temp & co2, then choice C is the clear answer.
What choice C says is high levels of co2 is present when the surrounding temp is low. If this observation is found, then we can't conclude that 'during periods of postglacial warming, co2 increased by 40%'.

jasleen89 · Answer

Q1. author is primarily concerned with doing which of the following?

(B) Describing a method of analysis that provides information regarding the relation between the carbon dioxide content of the Earth’s atmosphere and global temperature---- How is he showing a relation between CO2 and Global temperature?

(C) Presenting information that suggests that global temperature has increased over the last 160,000 years----- This sounds right as per the last sentence of para.

Can somebody explain how B is the answer for Q1?

Sajjad1994 · Answer

Explanation

Q1. In the passage, the author is primarily concerned with doing which of the following?

Difficulty Level:   600

Explanation

Let's break down the passage to understand why this is the main focus:

Analysis of prehistoric air trapped in tiny bubbles beneath the polar ice sheets:  The passage starts by discussing the analysis of air trapped in bubbles beneath polar ice sheets.

Composition of ice surrounding those bubbles:  The passage then goes on to explain that the composition of the ice surrounding these bubbles is used for estimating global temperature.

Correlation between carbon dioxide levels in the Earth’s atmosphere and global temperature over the last 160,000 years:  The author describes how this analysis of air bubbles and ice composition suggests a correlation between carbon dioxide levels and global temperature over a specific time frame.

Estimates of global temperature based on the relative abundances of hydrogen and deuterium:  The passage explains that global temperature estimates are derived from the relative abundances of hydrogen and deuterium in the ice, which is a method of analysis.

Estimates of global temperature based on carbon dioxide content:  Furthermore, the author discusses estimates of global temperature based on the carbon dioxide content of the trapped air.

Therefore, the main purpose of the passage is to describe and explain a method of analysis that provides information regarding the relationship between carbon dioxide content in the Earth's atmosphere and global temperature over the last 160,000 years.  Option (B)  accurately captures this focus. The passage does not primarily aim to describe new methods of estimating decreases in global temperature, present information suggesting global temperature has increased, or demonstrate the difficulty of arriving at a firm conclusion regarding the impact of carbon dioxide on global temperature, which rules out the other options.

Answer: B

Analysis of prehistoric air trapped in tiny bubbles beneath the polar

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Analysis of prehistoric air trapped in tiny bubbles beneath the polar

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