By measuring tiny amounts of radioactive elements in coral, scientists

Question

By measuring tiny amounts of radioactive elements in coral, scientists have recently discovered unexpectedly large errors in the traditional carbon-dating scale. Researchers say the coral experiments will not only alter the previously established dates of important prehistoric events but will also help to resolve the question of how quickly the earth warmed at the end of the last ice age.

These findings are based on a study of coral samples taken from reefs in the waters of Barbados. Researchers dated the coral using two different radioactive "clocks": the decay of carbon-14 and the decay of uranium to thorium. The latter entails the use of a mass spectrometer to measure the relative amounts of uranium and thorium isotopes in the coral. This method, now known as the thorium technique can date only a limited variety of materials and therefore can never completely replace the carbon-14 method. But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages.

The ages determined by the thorium technique suggest extreme fluctuations in the concentration of carbon-14, with the Ice Age's atmosphere holding up to 40 percent more carbon-14 than does today's. Researchers report using the thorium technique to re-calibrate the carbon-14 scale of the past 30,000 years, an advance one scientist describes as a “quantum leap." Their results suggest that the carbon-14 method occasionally has a large margin of error, producing dates of as many as 3,500 years too young for material that is in fact at least 20,000 years old. While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required.    1 
 1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community
B. surpasses that of carbon-14 testing
C. will change the focus of scientific research
D. is limited to certain types of materials
E. lies in its ability to measure calibration points in carbon-14

2 
 2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events
B. will help to settle questions about the end of the last ice age
C. were conducted at a variety of sites over several years
D. have helped to replace carbon-14 testing with the thorium technique
E. were conducted in order to compare the effectiveness of two different radioactive "clocks"

3 
 3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique.
B. Many scientists have doubted the accuracy of the thorium technique.
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.
D. Coral samples have greater concentrations of thorium than of carbon-14.
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.

4 
 4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method
B. as a substitute for the standard method for only those materials that do not contain carbon-14
C. as a tool to date a wider variety of materials than carbon dating can alone
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time
E. as a calibration device for the carbon-dating method

5 
 5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium
B. Measuring carbon-14 locked within organic material from plants and animals
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known
E. Assessing the rate of decay of all radioactive elements within certain organic material

6 
 6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.
B. The carbon-dating method is extremely inaccurate and therefore obsolete.
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others. 
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.

7 
 7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced
B. describing the advantages of an established method over newer, less universally applicable methods
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness
E. criticizing an established method but admitting that a suitable alternative has yet to be found

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Pankaj0901 · Answer

Answer:
1. D
2. B
3. C
4. B
5. A
6. B
7. D

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community
B. surpasses that of carbon-14 testing
C. will change the focus of scientific research
D. is limited to certain types of materials
E. lies in its ability to measure calibration points in carbon-14

Answer: D. As mentioned in the second paragraph: This method, now known as the thorium technique can date only a limited variety of materials and therefore can never completely replace the carbon-14 method.

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events
B. will help to settle questions about the end of the last ice age
C. were conducted at a variety of sites over several years
D. have helped to replace carbon-14 testing with the thorium technique
E. were conducted in order to compare the effectiveness of two different radioactive "clocks"

Answer B. From first paragraph: Researchers say the coral experiments will not only alter the previously established dates of important prehistoric events but will also help to resolve the question of how quickly the earth warmed at the end of the last ice age.

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique.
B. Many scientists have doubted the accuracy of the thorium technique.
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.
D. Coral samples have greater concentrations of thorium than of carbon-14.
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.

Answer C. Thorium technique provides accurate date. Option C explains the same thing in the form of an example. From the lines in the second paragraph: But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages.

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method
B. as a substitute for the standard method for only those materials that do not contain carbon-14
C. as a tool to date a wider variety of materials than carbon dating can alone
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time
E. as a calibration device for the carbon-dating method

Answer B. Since the Thorium technique cannot be used in all materials, it can act as a substitute for those materials at least that don't contain Carbon-14.

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium
B. Measuring carbon-14 locked within organic material from plants and animals
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known
E. Assessing the rate of decay of all radioactive elements within certain organic material

Answer A. It is clearly stated in the last paragraph: Their results suggest that the carbon-14 method occasionally has a large margin of error, producing dates of as many as 3,500 years too young for material that is in fact at least 20,000 years old. While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required.

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.
B. The carbon-dating method is extremely inaccurate and therefore obsolete.
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.

Confused between B & C. B sounds too harsh, but option C mentions 40,000 years ago (exaggerated from 30,000 years mentioned in the passage), hence eliminated C. I will go with B. The last passage gives example of errors and inaccuracy of carbon-dating.

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced
B. describing the advantages of an established method over newer, less universally applicable methods
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness
E. criticizing an established method but admitting that a suitable alternative has yet to be found

Answer D. Author has identified a flaw in carbon-dating and presented another method, Thorium technique. Correct answer.

ash124 · Answer

Understand the passage and try to create a map:

Identifying an error in the existing method 
Describe a different method that can rectify the errors
The magnitude of error in C14 method

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community
 Not given in the passage 
B. surpasses that of carbon-14 testing
 Not given in the passage 
C. will change the focus of scientific research
 the passage doesn't say it 
D. is limited to certain types of materials
 Given in the 2nd para. 
E. lies in its ability to measure calibration points in carbon-14
  thorium technique is not dependent on carbon-14 method

Answer D

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events
 It will correct the error not confirm 
B. will help to settle questions about the end of the last ice age
 Given in the 1st para. 
C. were conducted at a variety of sites over several years
 not given in the passage 
D. have helped to replace carbon-14 testing with the thorium technique
 thorium technique is not replacing carbon-14 testing 
E. were conducted in order to compare the effectiveness of two different radioactive "clocks"
 not given in the passage

Answer C

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique.
 Nothing is given about other techniques 
B. Many scientists have doubted the accuracy of the thorium technique.
 Not given 
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.
 Yes, given in the 3rd para. 
D. Coral samples have greater concentrations of thorium than of carbon-14.
no comparisons given
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.
 False statement based on 2nd para. 
 Answer C

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method
 Not given 
B. as a substitute for the standard method for only those materials that do not contain carbon-14
 Too narrow 
C. as a tool to date a wider variety of materials than carbon dating can alone
 thorium technique is limited to a certain matter 
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time
 Not given  
E. as a calibration device for the carbon-dating method
 yes, the Main point

Answer E

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium
 Not given 
B. Measuring carbon-14 locked within organic material from plants and animals
 Not given 
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques
Yes, supported
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known
 Not given 
E. Assessing the rate of decay of all radioactive elements within certain organic material
 Not given

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.
 Yes, the author agrees with it 
B. The carbon-dating method is extremely inaccurate and therefore obsolete.
 too extreme  
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.
 nowhere given 
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.
 nowhere given  
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.
 not mentioned in the passage

Answer A

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced
 no replacement is suggested in the passage 
B. describing the advantages of an established method over newer, less universally applicable methods
 disadvantages of the established method are given  
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages
 no comparison is done 
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness
 The crux of the passage 
E. criticizing an established method but admitting that a suitable alternative has yet to be found   
 not supported 
 Answer D

c93liu · Answer

Q1 - my answer is D)

A) - Not mentioned in the passage and seems like the contrary is actually implied.
B) - We know from the passage that the technique is more limited in application setting vs. Carbon-14, so B) is out.
C) - This is rather extreme. While thorium technique may help to calibrate results obtained from Carbon-14 and hence provide more accurate results and new insights, to say that it will change the focus of scientific research seems to be too exaggerated.
D) - Yes, this is directly stated in paragraph 2: "the thorium technique can date only a limited variety of materials"
E) - The dates obtained from the thorium technique provides calibration points, not the technique itself.

Q2 - my answer is B)

A) - Seems to be the contrary of what the passage is actually discussing.
B) - Yes, see paragraph 1: "will also help to resolve the question of how quickly the earth warmed at the end of the last ice age"
C) - We know the experiments were conducted from reefs in Barbados (so potentially a variety of sites), but not sure about "over several years" - no such mentions.
D) - This is the contrary of paragraph 2 of the passage: "... and therefore can never completely replace the carbon-14 method".
E) - This is not the main objective of the experiments.

Q3 - my answer is C)

A) - This option takes the passage to an extreme. Although in these specific experiments, the thorium technique complements Carbon-14, it is rather extreme to say that all dating techniques are more useful with the technique.
B) - This option is not mentioned at all in the passage.
C) - Yes. In paragraph 3, we know that Carbon-14 can produce "dates of as many as 3,500 years too young for material that is in fact at least 20,000 years old". 20,000 - 3,500 = 16,500.
D) - We do not know the relative concentration between the 2, other than the fact that coral reefs contain both.
E) - Again, we do not know this from the passage alone.

Q4 - my answer is E)
From paragraph 2: "But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages", suggesting that the thorium technique acts as an additional calibration of Carbon-14 dates.

A) - Complements, but not replaces Carbon-14.
B) - See A).
C) - This goes exactly the opposite of paragraph 2.
D) - The fluctuating amounts of Carbon-14 in the environment is the explanation for why Carbon-14 failed to provide an accurate reading, but not the direct use / result of the thorium technique.
E) - Yes, this matches with our thinking above.

Q5 - my answer is C)
Should be the combination of Carbon-14 with some calibration technique.

A) - Notice that we are talking about prehistoric materials generally. We know that the thorium technique has more limited application sets, so A) is out.
B) - The passage's discussion about coral reefs clearly provides one counter-example to this.
C) - Yes, this matches with our thinking above.
D) - Again, see A). Too narrow vs. the broadly discussed term prehistoric material.
E) - The passage only mentions two specific types of decay "clocks". Not sure about all radioactive decays.

Q6 - my answer is A)

A) - Yes, Carbon-14 + the thorium technique as discussed in the passage.
B) - Taking the passage to an extreme. Carbon-14 is more like the backbone.
C) - We do not know about the effective range of Carbon-14. This is not discussed in the passage.
D) - Also not discussed in the passage.
E) - See C) above.

Q7 - my answer is D)

A) - Inadequacies of Carbon-14, maybe, replacement of Carbon-14, no way.
B) - If this were true, we would be talking about how much better Carbon-14 is over the thorium technique. Not true.
C) - The passage talks about how Carbon-14 + thorium > Carbon-14 alone, not comparing the drawback of Carbon-14 vs. thorium.
D) - Yes. The weakness in Carbon-14 is from the fluctuating amount of Carbon-14 in the environment. Another method to mitigate this drawback is Carbon-14 + calibration technique (thorium).
E) - Not true. A suitable alternative is Carbon-14 + calibration technique.

SomeOneUnique · Answer

According to the best of my ability, kindly find the answer explanations below.

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community => Last line of the passage says scientists are surprised which means they have partially accepted otherwise they would come back with some argument. Moreover,  surprised hints positive  so scientists are positive, instead of a word like  'shocked' which hints negative  and could says scientists did not accept.  INCORRECT 
B. surpasses that of carbon-14 testing => Para 2 line 3 says opposite -  thorium technique can never completely replace  the carbon-14 method.  INCORRECT 
C. will change the focus of scientific research =>  Effectiveness would help scientists to move forward  with the research and  not to change the focus .  INCORRECT 
D. is limited to certain types of materials => PERFECT - Para 2 line 3 highlights this limitation -  thorium technique can date only a limited variety of materials .  CORRECT 
E. lies in its ability to measure calibration points in carbon-14 => thorium technique and carbon-14 method  are two different radioactive "clocks".   INCORRECT

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events => Para 3 second last line says "large margin of error, producing dates" which means  experiments conducted on coral show results against previously established dates and not confirm so . This choice says opposite and hence is  INCORRECT 
B. will help to settle questions about the end of the last ice age => This is a direct pick from Para 1 line 2.  CORRECT 
C. were conducted at a variety of sites over several years =>  Passage does not mention duration  - whether experiments were conducted for a few days or for several years.  INCORRECT 
D. have helped to replace carbon-14 testing with the thorium technique => Para 2 line 3 says opposite -  thorium technique can never completely replace  the carbon-14 method.  INCORRECT 
E. were conducted in order to compare the effectiveness of two different radioactive "clocks" => This choice talks about result of the study mentioned in Para 2 line 1 but the question is asking about experiments mentioned in Para 1 line 2. B wins over E due to a subtle difference.  INCORRECT

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

EXPLANATION: improvements in carbon-14 dating techniques would the drawback i.e. improve the accuracy.  
A. All dating techniques are more useful when calibrated with the thorium technique. => Passage is limited to only 2 dating techniques.  INCORRECT 
B. Many scientists have doubted the accuracy of the thorium technique. => Passage does not mention any scientist questioning/doubting the accuracy of any technique.  INCORRECT 
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago. PERFECT. This choice is inline with the explanation.  CORRECT 
D. Coral samples have greater concentrations of thorium than of carbon-14. => Passage does not mention anything about concentration.  INCORRECT 
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium. => Para 2 line 2 says  latter (thorium technique) entails the use of a mass spectrometer   INCORRECT

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

EXPLANATION: Para 2 last line says "But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages." which means thorium technique is most accurate.   
A. Experimenting with the new method of measuring the decay of uranium to thorium => We are not sure about what new methods are.  CORRECT 
B. Measuring carbon-14 locked within organic material from plants and animals => We are only talking about coral not general plants and animals.  INCORRECT 
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques => Calibration technique - discussed in the passage.  CORRECT 
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known => This is tricky. This choice compares 2 different techniques and a comparison can not answer most accurate method. Also, 'concentration of those elements in the environment' should refer to only carbon-14 as per last para first line but this choice refers to thorium and caron-14.  INCORRECT 
E. Assessing the rate of decay of all radioactive elements within certain organic material => Passage does not tell us whether assessing several, some or all elements would be most accurate.  INCORRECT

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies. IMO, out of all the choices this choice fits the author's opinion as each method mentioned in the passage has its own limitation.  CORRECT 
B. The carbon-dating method is extremely inaccurate and therefore obsolete.  INCORRECT 
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.  INCORRECT 
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.  INCORRECT 
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.  INCORRECT

Nirmesh83 · Answer

1.D
2.E
3.A
4.E
5.C
6.A
7.D
Not having time now else will love to describe each answers.

800gal · Answer

Passage Mapping ->
Paragraph One - Main Idea (Introducing a new finding )--> Coral Experiments have revealed something unexpected about C-dating, which may alter two things : established dates of prehistoric events + how fast the earth warmed at the end of ice age.

Paragraph Two- Main Idea(Expanding on the finding and how it was done) --> Coral Experiments done with two methods -> C-DATING and THORIUM TECHNIQUE, Thorium Tech can't fully replace C-Dating due to limited application materials but can work as a calibration method. (Suggests that the two can be used together to minimise error)

Paragraph Three - Main Idea (Consequences of Finding) Results of Thorium Tech reveals great margins of error in C-dating technique, combined usage of c-dating and thorium tech as calibration technique (Quantum Leap) scientists were aware of the existence of error but unaware of the magnitude of error.

QUESTION 1
 1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community

The effectiveness isn't accepted in the scientific community? No support in the passage for this statement.

B. surpasses that of carbon-14 testing

Not necessarily. It provides calibration points on existing C-14 dated materials, however the THORIUM technique is limited in materials.

C. will change the focus of scientific research

The focus of research hasn't changed from dating as it is. Too broad and out of scope.

D. is limited to certain types of materials

True. It can't measure others. CORRECT

E. lies in its ability to measure calibration points in carbon-14

Tempting. Calibration points in carbon 14? The passage suggests recalibrating the C-14 scale, this statement suggests that C-14 is being measured.

QUESTION 2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events

No. The passage states it will ALTER previously established dates (refer to map)

B. will help to settle questions about the end of the last ice age

Yes, there are doubts on how quickly the earth warmed at the end of the last ice age, which is a question about the end of the last ice age.
 
C. were conducted at a variety of sites over several years

No support found in passage for this.

D. have helped to replace carbon-14 testing with the thorium technique

The passage states c-14 can never truly be replaced by the thorium technique.

E. were conducted in order to compare the effectiveness of two different radioactive "clocks"
No, the passage has never stated WHY the experiments were conducted. In fact, the use of "unexpected" in the FIRST PARAGRAPH suggests that the the experiments were probably conducted for a whole other reason and hence the results they got were UNEXPECTED.

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?
(CR +RC --> INFERENCE)

A. All dating techniques are more useful when calibrated with the thorium technique.

Specifically states C-14 dating is improved with thorium technique, out of scope. Tempting though.

B. Many scientists have doubted the accuracy of the thorium technique.

No support.

C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.

Yes, the passage has stated that the new technique did reveal something that was thought to have occurred way earlier actually occurred 3500 years later.

D. Coral samples have greater concentrations of thorium than of carbon-14.

Again, no support in the passage for this statement.

E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.

M. Spectrometers specifically mentioned as used for measuring U:T ratio, not C-14. Out of Scope.

QUESTION 4. According to the passage, the best use of the dating method used on the Barbados coral would be
(This should be easy, stated in the last paragraph)

A. as a replacement for the carbon-14 method

No. Passage 2 states it can't be fully replaced.

B. as a substitute for the standard method for only those materials that do not contain carbon-14

Nope. Th Technique is actually recommended to be used alongside C-14 dating. Therefore, it can be used to measure materials containing C-14.

C. as a tool to date a wider variety of materials than carbon dating can alone

Factually incorrect (Factually--> as per the passage), Th Technique is more limited than C-14 dating in terms of materials.

D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time

True, this is one specific use case of the technique though.

E. as a calibration device for the carbon-dating method
Yes.

QUESTION 5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium

No. Infact this can't be applied to every method. And nowhere is it stated that SCIENTISTS consider it to be the most accurate.

B. Measuring carbon-14 locked within organic material from plants and animals

C-14 is stated as being considered quite inaccurate in certain ways.

C. Formulating deductions from the combined use of the carbon-dating and calibration techniques

YES. This has the most support in the last paragraph.

D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known

No, and out of scope.

E. Assessing the rate of decay of all radioactive elements within certain organic material
Out of scope.

QUESTION 6. With which of the following statements concerning carbon-dating would the author most likely agree?

(I Like to call these sneaky CR's --> Obviously the Answer Choice  must be true  given that the passage is true and the author agrees with the passage)

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.

YES! Clearly stated in the last paragraph and the second one how Thorium technique helps get rid of the inaccuracies in the C-14 dating method.

B. The carbon-dating method is extremely inaccurate and therefore obsolete.

Nope. No support.

C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.

Out of scope.

D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.

Out of scope. The only material limitation mentioned is for the Thorium technique.

E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.

Out of scope.

QUESTION 7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced
Inadequacies of C-14 dating has been presented, however a replacement has not been asserted.

B. describing the advantages of an established method over newer, less universally applicable methods

The established method would be C-14 and the newer method would be Thorium. The passage actually lays out a few advantages Thorium has over C-14 and vice versa too. So no.

C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages

This has a shred of truth to it, however this isn't the PRIMARY CONCERN.

D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness

Yes. The whole idea of the passage is to lay out how one method's drawbacks can be improved by another method.
 
E. criticizing an established method but admitting that a suitable alternative has yet to be found

The criticism does exist, however the author only admits to C-14 never being fully replaced as part of the passage, the over arching theme is still how the conjuction of the two methods has been revolutionary.

Rohitq · Answer

Passage Brief

Para 1 - Introduce the problem , i.e. difference or incorrect measurement of corals---> will modify some established dates and answer some question to ice age era 
Para 2 - Introduce 2 methods ---> Carbon -14 and some method that measure decay date of uranium to thorium, AKA Thorium technique---> also mentions that this new technique although gives quiet accurate dates, it is only applicable to few scenarios or materials- inference- cannot replay Carbon -14 which has wide scope 
Para 3 - Explains how the carbon technique approximates incorrect dates and how it is made better by re-calibrating it with Thorium technique.

Lets check on questions now;

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community ( There is no such mention of scientific community rejecting the technique, in fact they want to make use of the technique to estimate the correct dates  )
B. surpasses that of carbon-14 testing ( No, we know that Thorium technique has narrow scope of application, hence carbon is still a widely used method )
C. will change the focus of scientific research ( No, this is irrelevant )
D. is limited to certain types of materials ( Yes, we know it has limited scope of application )
E. lies in its ability to measure calibration points in carbon-14 ( it is not the helping us with determining the effectiveness of thorium technique, it is one of its use )

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events ( Passage states it will alter the dates not confirm them  )
B. will help to settle questions about the end of the last ice age ( although passage states it that how quickly earth warmed post the end of ice age, I still feel this is closer  )
C. were conducted at a variety of sites over several years  (OFS) 
D. have helped to replace carbon-14 testing with the thorium technique ( We did not replace but use it to re calibrate the carbon 14 estimates )
E. were conducted in order to compare the effectiveness of two different radioactive "clocks" ( No where in passage we are comparing the effectiveness of the 2 technique  )

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique. ( not is passage scope and ALL is strong word  )
B. Many scientists have doubted the accuracy of the thorium technique. ( They want to use the technique never doubted it  )
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago. ( This is something given in the 3rd para , hence close one )
D. Coral samples have greater concentrations of thorium than of carbon-14. ( We dont know this from the passage )
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium. ( The method is only used for the latter, hence wrong )

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method ( To strong, we are not replacing but re- calibrating the results of carbon -14 )
B. as a substitute for the standard method for only those materials that do not contain carbon-14 ( We are not substituting carbon -14 and this is not inferred from the passage )
C. as a tool to date a wider variety of materials than carbon dating can alone ( Thorium technique has limited scope so not true from passage) 
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time ( OFS )
E. as a calibration device for the carbon-dating method ( True, from the 3rd paragraph )

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium ( Not completely true )
B. Measuring carbon-14 locked within organic material from plants and animals ( no true from the passage )
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques ( this is something we can infer from the 3rd para )
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known ( we are no where comparing the amount of any element found in the organic materials )
E. Assessing the rate of decay of all radioactive elements within certain organic material ( Decay method is used to estimated the dates, but apart from that we are not accessing rate of decay of all radioactive material )

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies. ( This is the closest one and hence the correct choice. Since we are rectifying the wrong dates by re calibrating it with the thorium technique  )
B. The carbon-dating method is extremely inaccurate and therefore obsolete. ( To strong, plus no where this is mentioned )
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago. ( in 3rd para, we see that it can put some younger dates for old events but increasing range of estimate is too far fetched )
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others. ( Passage doesn't state this, wrong inference, we are only talking about a certain scenario in passage and not generalizing it for all )

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced ( We are not replacing the carbon technique, only re calibrating it )
B. describing the advantages of an established method over newer, less universally applicable methods ( We are not discarding the advantage of carbon method, but it is mentioned in the passage that the dates might be wrong and can be altered with proper calibration from another technique )
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages ( We are not talking on the disadvantages of both the methods, OFS )
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness ( This looks like a soothing answer, yes, there are some drawbacks of carbon 14 method but we can reduce or minimize the error via a calibration from another method )
E. criticizing an established method but admitting that a suitable alternative has yet to be found ( No we know that there is an alternative from the passage, clearly a wrong choice)

zyt · Answer

1. According to the passage, the effectiveness of the thorium technique
A. is not widely accepted in the scientific community. ..not mentioned in the passage. 
B. surpasses that of carbon-14 testing..... not really as though it is more accurate, it cant be used (not affective) on all types of materials.
C. will change the focus of scientific research...not mentioned .
  D. i s limited to certain types of materials   ..... clearly mentioned in the passage. 
E. lies in its ability to measure calibration points in carbon-14... .this is one of the uses of thorium, its not the reason of the technique's effectiveness.

2.. According to the passage, the experiments conducted on coral
A. will confirm previously established dates of prehistoric events....in correct, will probably change the dates of prehistoric events
 B. will help to settle questions about the end of the last ice age ....Correct, clearly mentioned
C. were conducted at a variety of sites over several years...not mentioned .
D. have helped to replace carbon-14 testing with the thorium technique...not mentioned, as both techniques are used.
E. were conducted in order to compare the effectiveness of two different radioactive "clocks"......two techniques used but ? effectiveness compared not mentioned

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique..... some may not require, only compared to carbon 14 dating the paragraph 
B. Many scientists have doubted the accuracy of the thorium technique.... no thorium is more useful 
C.  Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago. ....mentioned
D. Coral samples have greater concentrations of thorium than of carbon-14...... not stated 
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium... mass spectrometrs are used for thorium study

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method.. .not it can be used in addition to 
B. as a substitute for the standard method for only those materials that do not contain carbon-14... not mentioned 
C. as a tool to date a wider variety of materials than carbon dating can alone... not accurate 
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time... .not mentioned  
 E. as a calibration device for the carbon-dating method .... yes mentioned

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium ..one of the techniques, but not most accurate 
B. Measuring carbon-14 locked within organic material from plants and animals... one of the techniques, but not most accurate 
C . F ormulating deductions from the combined use of the carbon-dating and calibration techniques ..correct  
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known... only carbon 14 in environment mentioned in third paragraph 
E. Assessing the rate of decay of all radioactive elements within certain organic material.... not correct as not most accurate

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies. .. clearly mentioned that it be used with thorium technique 
B. The carbon-dating method is extremely inaccurate and therefore obsolete... no, too strong a choice 
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago. ..no 
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others... no 
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old... no

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced...no
B. describing the advantages of an established method over newer, less universally applicable methods..no
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages..one one alternative method discussed
 D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness . .correct...weakness of carbon dating improved with thorium technique 
E. criticizing an established method but admitting that a suitable alternative has yet to be found... no

Acme · Answer

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community :Incorrect – There is no mention about the acceptance
B. surpasses that of carbon-14 testing : Incorrect – No mention on which method is superior
C. will change the focus of scientific research : Incorrect- The focus change in the research is never mentioned 
D. is limited to certain types of materials :correct. Passage mentions abt limitation of this new technique
E. lies in its ability to measure calibration points in carbon-14 :Incorrect

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events : Incorrect- As per passage only alter the dates established 
B. will help to settle questions about the end of the last ice age : Incorrect- Passage mentions about how quickly earth warmed.
C. were conducted at a variety of sites over several years: Correct- As per POE
D. have helped to replace carbon-14 testing with the thorium technique -Incorrect- The new technique is not replacement
E. were conducted in order to compare the effectiveness of two different radioactive "clocks" : Incorrect – This not the purpose of the experiment

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique. :Incorrect – Usage of All and no mention about the usefulness of the technique
B. Many scientists have doubted the accuracy of the thorium technique.: Incorrect – no mention about the scientists doubting the accuracy of the thorium tech
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.: correct – as per example in the passage
D. Coral samples have greater concentrations of thorium than of carbon-14. : Incorrect – No mention abt the concentrations 
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.: Incorrect – Mass spec is mentioned only for thorium tech

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method – Incorrect : This was not mentioned as a replacement
B. as a substitute for the standard method for only those materials that do not contain carbon-14- Incorrect – No mention about the specific type to be replaced
C. as a tool to date a wider variety of materials than carbon dating can alone : Incorrect as per the passage.
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time -Incorrect : This is not a method only to identify the fluctuating amounts
E. as a calibration device for the carbon-dating method: correct – As per last sentence of 2nd para

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium- Correct as mentioned in the last sentence of para1
B. Measuring carbon-14 locked within organic material from plants and animals:Incorrect – No mention about the material from plants and animals
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques : Incorrect- No clear mention about the combined usage
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known Incorrect-The second part of this option is inaccurate
E. Assessing the rate of decay of all radioactive elements within certain organic material: Incorrect-No mention about the rate of decay of all elements

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.—Incorrect -Other techniques ?
B. The carbon-dating method is extremely inaccurate and therefore obsolete.Incorrect-extreme usage of words
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago. -Incorrect – no mention about how accurately the dating can happen
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others. -- Correct
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.: Incorrect – No mention about the specific years

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced -Incorrect – replacement is not the primary purpose
B. describing the advantages of an established method over newer, less universally applicable methods : Incorrect – less universally methods?
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages – Incorrect: Equally serious disadvantage?
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness --Correct
E. criticizing an established method but admitting that a suitable alternative has yet to be found-Incorrect-Not critised the carbon dating method

Gaudapada · Answer

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community  
This is never mentioned in the passage. The only drawback of the thorium technique stated by the author is the limited variety of materials that it can date.

B. surpasses that of carbon-14 testing  
Thorium technique is not mentioned to be superior to carbon-14 technique. "The thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages", but author never states that it is superior by itself.

C. will change the focus of scientific research  
This could be true of the Barbados study but author never directly mentions that the thorium technique by itself is revolutionary.

D. is limited to certain types of materials  
 CORRECT :  This is directly stated in  paragraph 2 
 "This method, now known as the thorium technique can date only a limited variety of materials and therefore can never completely replace the carbon-14 method"

E. lies in its ability to measure calibration points in carbon-14  
The thorium technique is not dependent on the carbon technique. When used in conjunction with carbon-14 this is true but the use of thorium technique as a calibration for the carbon-14 technique has no relevance to the thorium technique's own effectiveness.

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events  
The experiments achieved the opposite effect, altering previously established dates of prehistoric events.

B. will help to settle questions about the end of the last ice age  
 CORRECT :  This is mentioned explicitly in  paragraph 1 
 "Researchers say the coral experiments will not only alter the previously established dates of important prehistoric events but will also help to resolve the question of how quickly the earth warmed at the end of the last ice age."

C. were conducted at a variety of sites over several years  
from  paragraph 2 , the experiments were conducted only on the Barbados site. Hence  variety of sites  is incorrect.

D. have helped to replace carbon-14 testing with the thorium technique  
From  paragraph 3 , The thorium technique is used as calibration for the carbbon-14 scale. Hence carbon-14 has not been  replaced

E. were conducted in order to compare the effectiveness of two different radioactive "clocks"  
While two different clocks were used, This was not the purpose of the experiment. Answer choice  E  conflates methodology with result.

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique.  
While the passage says that carbon-14 technique is more useful when calibrated with thorium technique, it would be a generalization to assume the same for  ALL  dating techniques.

B. Many scientists have doubted the accuracy of the thorium technique.  
This is never mentioned in the passage. The drawback of thorium technique (limited to certain materials) is mentioned but this does not mean that scientists doubt the accuracy of thorium technique as a whole.

C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.  
 CORRECT :  The dates in  paragraph 3  are mentioned in an approximate way. Since no other option is favorable,  C  must be correct.

D. Coral samples have greater concentrations of thorium than of carbon-14.  
Relative concentrations of thorium and carbon-14 in coral samples is not mentioned in the passage.

E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.  
from  paragraph 2 ,  "Researchers dated the coral using two different radioactive "clocks": the decay of carbon-14 and the decay of uranium to thorium. The latter entails the use of a mass spectrometer to measure the relative amounts of uranium and thorium isotopes in the coral. This method" 
the latter method(thorium) is mentioned to use mass spectrometers but nothing is said about the carbon-14 technique in this regard.

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method  
Thorium technique is not a  REPLACEMENT  for the carbon-14 method.

B. as a substitute for the standard method for only those materials that do not contain carbon-14  
While this may be a use for thorium dating, it is not mentioned by the  AUTHOR

C. as a tool to date a wider variety of materials than carbon dating can alone  
The main crux of the passage is that the thorium technique, when used as a calibration for the carbon-14 scale provide provide more accurate dates for established prehistoric events. The dating of materials is not the focus of the passage, the dating of prehistoric events is.

D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time  
from  paragraph 3 ,  "The ages determined by the thorium technique suggest extreme fluctuations in the concentration of carbon-14, with the Ice Age's atmosphere holding up to 40 percent more carbon-14 than does today's" 
The extreme fluctuations is carbon-14 caused the inaccuracy of dates. Thorium techniques suggest extreme fluctuations but nowhere is it mentioned that the amount of fluctuation can be determined.

E. as a calibration device for the carbon-dating method  
 CORRECT :  This is directly mentioned in  paragraph 3 .  "But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages."

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium  
The new method(thorium) by itself is not mentioned as the most accurate in this passage.

B. Measuring carbon-14 locked within organic material from plants and animals  
the distinction between organic and inorganic material is never made in the passage. We can quickly dismiss this answer.

C. Formulating deductions from the combined use of the carbon-dating and calibration techniques  
 CORRECT :  This is the crux of  paragraph 3 
 ""Researchers report using the thorium technique to re-calibrate the carbon-14 scale of the past 30,000 years, an advance one scientist describes as a “quantum leap."

D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known  
Comparison of thorium and carbon-14 sounds suspicious. Author mentions recalibration of carbon-14 scale with thorium method, not a comparison between the two. Furthermore, thorium concentration in the environment is never mentioned in the passage.

E. Assessing the rate of decay of all radioactive elements within certain organic material  
Passage never mentions any method involving rate of decay of  ALL  radioactive elements.

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.  
 CORRECT :  Author never dismisses the carbon-14 technique. It can be used in conjunction with other techniques(like thorium technique) to yield accurate dates.

B. The carbon-dating method is extremely inaccurate and therefore obsolete.  
This is directly contradicted in  paragraph 3 . While the technique can be inaccurate by itself, it can still be used in conjunction with other techniques.

C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.  
The specific mention of  as many as 40,000 years ago  is suspicious. No such date is mentioned or can be inferred from the passage.

D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.  
The accuracy of carbon dating method is never mentioned to be a function of the material being tested. No mention of organic matter is ever made in the passage.

E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.  
Passage never suggests that the carbon-dating method is more accurate for objects younger than 8000 years or that it is inaccurate for objects older than 8000 years old. This date is neither mentioned nor can it be inferred.

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced  
Author never advocates for a  REPLACEMENT  of the carbon-14 technique.

B. describing the advantages of an established method over newer, less universally applicable methods  
Author mentions the disadvantage of the  ESTABLISHED  method (carbon-14) so this option cannot be true.

C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages  
This misses the point of the passage. The primary concern of the author is to describe the significance of the Barbados experiment, and how thorium technique in conjunction with carbon-14 is a " quantum leap " in dating techniques.

D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness  
 CORRECT :  This answer best fits the primary concern of the author. A weakness in carbon-14 method is identified, and another method(thorium) is presented which could minimize the impact of the weakness.

E. criticizing an established method but admitting that a suitable alternative has yet to be found  
This option is incorrect because a suitable option is described. ( a conjunction of the two techniques).

rvgmat12 · Answer

1. According to the passage, the effectiveness of the thorium technique
A. is not widely accepted in the scientific community
Incorrect

B. surpasses that of carbon-14 testing
Incorrect. It is mentioned that thorium technique cannot replace carbon dating

C. will change the focus of scientific research
Incorrect

D. is limited to certain types of materials
Incorrect. The effectiveness is not limited to certain types of materials but can be used to calibrate carbon-14 dating technique

E. lies in its ability to measure calibration points in carbon-14
Correct

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events
Incorrect. It is mentioned that there is variance between new evidence and the previously established dates

B. will help to settle questions about the end of the last ice age
Incorrect. It is mentioned that it can answer questions about

C. were conducted at a variety of sites over several years
Incorrect. This was in Barbados

D. have helped to replace carbon-14 testing with the thorium technique
Incorrect. Thorium technique cannot fully replace carbon-14 testing

E. were conducted in order to compare the effectiveness of two different radioactive "clocks"
Correct

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?
A. All dating techniques are more useful when calibrated with the thorium technique.
All dating techniques - too extreme. Only carbon-14 and thorium dating techniques are mentioned. Incorrect

B. Many scientists have doubted the accuracy of the thorium technique.
Incorrect. Out of scope

C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago.
Correct. It is mentioned that the margin of error is 3500 years

D. Coral samples have greater concentrations of thorium than of carbon-14.
Incorrect. Out of scope

E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.
Incorrect. Out of scope

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method
Incorrect. It is mentioned that this cannot fully replace carbon-14 method

B. as a substitute for the standard method for only those materials that do not contain carbon-14
Incorrect. Out of scope

C. as a tool to date a wider variety of materials than carbon dating can alone
Incorrect. thorium technique cannot date a wider variety of materials than carbon dating

D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time
Incorrect

E. as a calibration device for the carbon-dating method
Yes, correct

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium
Correct

B. Measuring carbon-14 locked within organic material from plants and animals
Incorrect. This is neither mentioned or inferred

C. Formulating deductions from the combined use of the carbon-dating and calibration techniques
No, this is not the most accurate. The margin of error for carbon-dating can be 3500 years

D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known
Incorrect. This is neither mentioned or inferred

E. Assessing the rate of decay of all radioactive elements within certain organic material
Incorrect. This is neither mentioned or inferred

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.
Correct

B. The carbon-dating method is extremely inaccurate and therefore obsolete.
No. The author mentions that carbon dating cannot be completely replaced

C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago.
Incorrect. This is not mentioned or inferred

D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others.
Incorrect. This is not mentioned or inferred

E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old.
Incorrect. This is not mentioned or inferred

7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced
No, the author doesn't mention that carbon-14 dating must be replaced

B. describing the advantages of an established method over newer, less universally applicable methods
Incorrect. throrium based dating method is newer and more accurate

C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages
Incorrect

D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness
Correct

E. criticizing an established method but admitting that a suitable alternative has yet to be found
Incorrect

Haridas800 · Answer

1.Ans E ( lies in its ability to measure calibration points in carbon-14)

A. is not widely accepted in the scientific community --- Not Relevant
B. surpasses that of carbon-14 testing -- Yes but that does not prove the effectiveness
C. will change the focus of scientific research -- Not relevant
D. is limited to certain types of materials -- This looks good but not effective

2. Ans B. will help to settle questions about the end of the last ice age.

A. will confirm previously established dates of prehistoric events --- NR
C. were conducted at a variety of sites over several years --NR
D. have helped to replace carbon-14 testing with the thorium technique -- No but this also a technique
E. were conducted in order to compare the effectiveness of two different radioactive "clocks" -- NR

3. Ans E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium.

4. Ans D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time.

5. Ans A. Experimenting with the new method of measuring the decay of uranium to thorium.

6. Ans A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies.

7. Ans C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages

snscatter · Answer

1. According to the passage, the effectiveness of the thorium technique

A. is not widely accepted in the scientific community –  No, cant refer that from the passage 
B. surpasses that of carbon-14 testing –  No, we have cons of the thorium technique mentioned in the passage vs carbon-14 
C. will change the focus of scientific research –  No, cant refer that from the passage 
D. is limited to certain types of materials –  Yes, referring to line “This method, now known as the thorium technique can date only a limited variety of materials” 
E. lies in its ability to measure calibration points in carbon-14 –  No, this is not the only point of effectiveness of this technique.

2. According to the passage, the experiments conducted on coral

A. will confirm previously established dates of prehistoric events –  No, this options states a partial purpose 
B. will help to settle questions about the end of the last ice age –  No, this option states a partial purpose 
C. were conducted at a variety of sites over several years –  No, Cant refer that from the passage. 
D. have helped to replace carbon-14 testing with the thorium technique –  No, it has not replaced the technique. Cant refer that from the passage.  
E. were conducted in order to compare the effectiveness of two different radioactive "clocks" –  Yes, the passage in 2nd and 3rd para compare these two “clocks” and tell how traditional method of carbon dating has a huge margin of error which thorium technique can help resolve. These experiments had not taken place had this was not known – “While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required.”

3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques?

A. All dating techniques are more useful when calibrated with the thorium technique. --  No, Cant refer that from the passage. 
B. Many scientists have doubted the accuracy of the thorium technique. --  No, Cant refer that from the passage. 
C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago. –  Yes, from the line “Their results suggest that the carbon-14 method occasionally has a large margin of error, producing dates of as many as 3,500 years too young for material that is in fact at least 20,000 years old. “ 
D. Coral samples have greater concentrations of thorium than of carbon-14. --  No, Cant refer that from the passage. 
E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium. --  No, Cant refer that from the passage.

4. According to the passage, the best use of the dating method used on the Barbados coral would be

A. as a replacement for the carbon-14 method –  No, refer to line “This method, now known as the thorium technique can date only a limited variety of materials and therefore can never completely replace the carbon-14 “ 
B. as a substitute for the standard method for only those materials that do not contain carbon-14 –  No, if they do not contain carbon 14 that does not mean they surely contain radioactive elements 
C. as a tool to date a wider variety of materials than carbon dating can alone –  No, we know that thorium technique is applicable on a small subset of materials on which carbon dating can be done 
D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time –  No, although this point is mentioned in the first line of last para but is not talked about as the best use of dating method 
E. as a calibration device for the carbon-dating method –  Yes, refer to line “But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages.”

5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate?

A. Experimenting with the new method of measuring the decay of uranium to thorium –  No, thorium technique alone is not suggested. It is used in collaboration with carbon dating. 
B. Measuring carbon-14 locked within organic material from plants and animals –  No, not mentioned in the passage 
C. Formulating deductions from the combined use of the carbon-dating and calibration techniques –  Yes, this is the one. “While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required.” This shows that the scientists accept calibration points given by thorium technique and these points will be used to adjust the base scale derived through carbon dating. 
D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known –  No, not mentioned in the passage 
E. Assessing the rate of decay of all radioactive elements within certain organic material –  No, not mentioned in the passage

6. With which of the following statements concerning carbon-dating would the author most likely agree?

A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies. –  Yes, this is the one. “While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required.” This shows that the scientists accept calibration points given by thorium technique and these points will be used to adjust the base scale derived through carbon dating. 
B. The carbon-dating method is extremely inaccurate and therefore obsolete. –  No, not mentioned in the passage 
C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago. -  No, not mentioned in the passage 
D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others. -  No, not mentioned in the passage 
E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old. -  No, not mentioned in the passage
 
7. The author is primarily concerned with

A. presenting the inadequacies of one method and the reasons it should be replaced –  No, author does not talk about replacing any method with the other 
B. describing the advantages of an established method over newer, less universally applicable methods -  No. Although the passage does tell benefits of Carbon Dating over Thorium technique but that is not the sole point which the author wants to convey 
C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages –  No. Although the passage does tell drawbacks of Thorium technique and Carbon Dating technique but that is not the sole point which the author wants to convey 
D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness –  Yes, in the last para author talks about combining results from both methods to get an accurate scale 
E. criticizing an established method but admitting that a suitable alternative has yet to be found –  No, this is not what the author is concerned with

irisjojojo · Answer

Question 1: D "This method, now known as the thorium technique can date only a limited variety of materials and therefore can never completely replace the carbon-14 method. But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages." Question 2: B A --> "confirm" is wrong here. The coral experiments is used to correct ("alter") the previous established erroneous date C --> "at a variety of sites over several years" --> not mentioned D --> the passage never says carbon-14 testing can be replaced (in fact, it suggests the other way around. ) E --> nope, the purpose is not for comparison Question 3: C A --> " All dating techniques are more useful" --> nope B --> "Many scientists have doubted" --> nope nope, "doubt" is never mentioned in the paragraph D --> have greater concentrations --> no evidence E --> not sure where the passage mentions "mass spectrometer" Question 4: E A --> can not substitute because... "can date only a limited variety of materials and therefore can never completely replace the carbon-14 method" B --> the concept of " only " (limitation) is not mentioned in the passage C --> true, but not the best use of the method C --> "at a specific time" --> not true E is better than D because the author indicates in the last sentence: "While carbon-14 specialists knew the scale needed correction, most were surprised at the magnitude of the correction that was required." Thus, we can conclude that thorium technique is used to calibrate and serves as a supplement of the carbon-dating method. Question 5: C D --> knowing the concentration of elements is not needed From the experience of the previous question, we can deduct that the answer should be C, the combination of the two methods. Question 6: A B --> obsolete? --> of course not C --> "as many as 40,000 years ago" suggests that the accuracy is limited to 40,000 years ago, but that is not the case D --> not mentioned; "less accurate for others (substances)" --> not justified E --> not mentioned; "most useful" --> not justified A --> compatible with the passage (discussed multiple times in previous question.) Question 7: D A --> stated many times, NOT replaced B --> the passage is NOT describing the "advantages" of carbon-dating method! C --> "evaluating the drawbacks of a new method" totally wrong. Thorium technique may have limitation, but the author is definitely not focusing on its disadvantages. E --> "has yet to be found" --> nope --> suitable alternative is not perfect, but is discovered. Finally done, mission complete

RohitSaluja · Answer

Q1. According to the passage, the effectiveness of the thorium technique - Answer E A. is not widely accepted in the scientific community - Nowhere it is mentioned that thorium technique isn't accepted, instead it is used to calibrate the errors in c-14, so eliminate this B. surpasses that of carbon-14 testing - No the passage states that thorium cant replace C-14 testing, so eliminate C. will change the focus of scientific research - Never mentioned in the passage D. is limited to certain types of materials - this is true but that is not why it is effective E. lies in its ability to measure calibration points in carbon-14 - Yes this is what it is essentially used for and unfortunately, I selected the wrong option while answering

2. According to the passage, the experiments conducted on coral - Answer B A. will confirm previously established dates of prehistoric events - The passage mention that it will alter the dates not confirm, so this is out B. will help to settle questions about the end of the last ice age - Directly mentioned in the passage C. were conducted at a variety of sites over several years - Never mentioned in the passage, so this is out D. have helped to replace carbon-14 testing with the thorium technique - The passage states that it can never replace but can be used to calibrate, eliminate this E. were conducted in order to compare the effectiveness of two different radioactive "clocks" - Nope never mentioned in passage 3. Which of the following can be inferred from the information in the passage about improvements in carbon-14 dating techniques? - Answer C A. All dating techniques are more useful when calibrated with the thorium technique. - The keyword here is 'All', the passage only talks about C-14 and thoium, so we cant generalise the information, hence eliminate B. Many scientists have doubted the accuracy of the thorium technique. - Never mentioned in the passage C. Some events previously believed to have occurred around 16,500 years ago may have occurred around 20,000 years ago. - Can be inferred from last paragraph in passage D. Coral samples have greater concentrations of thorium than of carbon-14. - Never mentioned in the passage E. Mass spectrometers can be used to measure carbon-14 as well as the ratio of uranium to thorium. - Never mentioned in the passage 4. According to the passage, the best use of the dating method used on the Barbados coral would be - Answer E A. as a replacement for the carbon-14 method -Passage never mentioned one method can be replaced by another B. as a substitute for the standard method for only those materials that do not contain carbon-14 - Not mentioned anywhere C. as a tool to date a wider variety of materials than carbon dating can alone - Limitation of C-14 methods are not discussed in passage D. to determine the fluctuating amounts of carbon-14 in the environment at a specific time - Not mentioned E. as a calibration device for the carbon-dating method - Directly mention in passage - Correct answer choice 5. The passage suggests that scientists consider which of the following methods of dating prehistoric material to be the most accurate? - Answer C A. Experimenting with the new method of measuring the decay of uranium to thorium - Not mentioned and cant be inferred B. Measuring carbon-14 locked within organic material from plants and animals - Nowhere in the passage any organic material is referred to C. Formulating deductions from the combined use of the carbon-dating and calibration techniques - Given there are margin of errors in C-14, that's where thorium techniques comes in handy to calibrate for the error, hence this is the correct answer choice D. Comparing thorium and carbon-14 found in the organic material in which the concentration of those elements in the environment is known - Nowhere in the passage any organic material is referred to E. Assessing the rate of decay of all radioactive elements within certain organic material - Same as D 6. With which of the following statements concerning carbon-dating would the author most likely agree? - Correct answer A The passage mentioned that C-14 has a wide range of errors and which can be calibrated by thorium techniques and options A fits the bill perfectly, hence the correct answer A. the carbon-dating method should be used in conjunction with other techniques that compensate for possible inaccuracies. B. The carbon-dating method is extremely inaccurate and therefore obsolete. C. With improved calibration, carbon dating can accurately date events that occurred as many as 40,000 years ago. D. The carbon-dating method should be considered accurate for certain organic substances but less accurate for others. E. The carbon-dating method is most useful in measuring the age of objects less than 8,000 years old 7. The author is primarily concerned with - Option D The author presents the two techniques and goes on to mention the inherent weakness in 1 and then present how can it be improved to minimize the impact, hence D is the correct answer choice A. presenting the inadequacies of one method and the reasons it should be replaced B. describing the advantages of an established method over newer, less universally applicable methods C. evaluating the drawbacks of a new method in comparison with other methods that have equally serious, but different disadvantages D. identifying a weakness inherent in one method and presenting another method that could somewhat minimize the impact of this weakness E. criticizing an established method but admitting that a suitable alternative has yet to be found

Sajjad1994 · Answer

Hello everyone!

Thank you for participating in Day 1 questions, OAs are revealed and also the competition mode is off now, Don't edit or modify your explanations. Day 2 questions have been posted.

neutronstar · Answer

Sajjad1994 · Answer

Here is my response to passage #2

Question #1
Difficulty Level: 600
Second lucrative asnwer choice is E

Question #2
Difficulty Level: 700-750
Second lucrative asnwer choice is E

Question #3
Difficulty Level: 500
Second lucrative asnwer is A

Question #4
Difficulty Level: 500
Second lucrative asnwer is D

Question #5
Difficulty Level: 700
Second lucrative asnwer is A

Question #6
Difficulty Level: 500
No other answer is even near

Question #7
Difficulty Level: 500
No other answer is even near

Excellent reasoning and excellent format by  Gaudapada  (10/10)
Excellent reasoning  c93liu  (9.5/10)
 800gal  and  Rohitq  (9/10)
 snscatter  (8/10)
 zyt  and irisjojojo (7/10)

Rest all explanations are either average or below average. Keep trying to improve you have still 8 passages remaining.

Good luck with the upcoming passages.

SatvikVedala · Answer

Since Question 1 asks about the effectiveness of Thorium Technique

From the passage (second para end) it is mentioned " But the thorium dates do provide valuable calibration points that provide a clearer picture of "real" calendar ages. "

isn't it an evidence to conclude  The effectiveness of Thorium Technique surpasses that of Carbon-14

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By measuring tiny amounts of radioactive elements in coral, scientists

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GMAT Reading Comprehension (RC) Questions

By measuring tiny amounts of radioactive elements in coral, scientists

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615 to 715 in 15 Days (Ria's Strategies)

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