Analysis of the motions of stars in the vicinity of the Sun indicates

Question

Analysis of the motions of stars in the vicinity of the Sun indicates that between one-half and three-quarters of the mass in the solar neighborhood has not been identified with visible stars or gas. Conventionally it has been assumed that this local unseen mass exists in the form of very dim, low-mass stars called brown dwarfs. Although this possibility cannot be excluded, inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars.

An attractive alternative is that stellar remnants, the dark matter left behind by the collapse of stars at least ten times as massive as the Sun, may account for this unseen mass. Although the formation of massive stars does not predominate at present in the solar neighborhood, it may well have been more important in the past, when the amount of interstellar gas and the rate of star formation were greater. Remnants of earlier generations of massive stars would then become an important contributor to the total mass in the solar neighborhood.

A model for the content and evolution of the solar neighborhood can readily be constructed in which all the unseen mass is accounted for as remnants. The model requires that the ratio of massive stars to smaller stars formed was higher at earlier times. Like an earlier model proposed by Schmidt that makes the same assumption, this model can account for the variation with stellar age in the abundance of elements such as oxygen in nearby stars. Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas. The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, can therefore be explained if the proportion of massive stars was higher at earlier times. It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass.  
 1 
 1. The author states which of the following about oxygen in the universe?

A. Its presence is due largely to the formation of low-mass stars.
B. It is less abundant in the stars than it is in the interstellar gas.
C. Its presence is more difficult to explain than is the presence of unseen matter.
D. It appears to be less abundant than it would be if conventional theories of star formation were correct.
E. It increased rapidly in abundance during an earlier period and has since increased more slowly.

2 
 2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is

A. well confirmed by observation
B. known to be incorrect
C. indirectly supported by Schmidt's model
D. a recently proposed and interesting hypothesis
E. possibly correct but more likely mistaken

3 
 3. Which of the following, if true, would most weaken support for the model described in lines 21-29? ( Text in Red )

A. Most of the mass in the solar neighborhood is to the form of stellar remnants.
B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed.
C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time.
D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized.
E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now.

4 
 4. According to the passage, Schmidt's model was originally created for which of the following purposes?

A. To explain the relative amounts of various chemicals present in stars
B. To account for the unseen mass in the solar neighborhood
C. To provide an alternative to the conventional theory of star formation
D. To describe the formation of stellar remnants
E. To determine the relative rates at which high-mass and low-mass stars arc formed

5 
 5. According to the passage which of the following was greater in the past?

A. The amount of oxygen in the universe
B. The number of brown-dwarf stars in the universe
C. The amount of interstellar gas in the solar neighborhood
D. The number of stellar remnants in the solar neighborhood
E. The number of stars of very low mass in the vicinity of the Sun

6 
 6. The author indicates that which of the following is an interesting feature of Schmidt's model?

A. It is much simpler than its rivals.
B. It does not rely on any unproven assumptions
C. It builds on well-established aspects of the conventional model of star formation.
D. It may be able to account for something else in addition to what it was created to explain.
E. It may allow for the prediction of future star formation as well as the explanation of past formation.

7 
 7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

A. There is less unseen mass in the solar neighborhood than had been believed.
B. The rate at which high-mass stars have been formed has remained constant.
C. The rate of star formation has been increasing since the origin of the universe.
D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars.
E. The amount of interstellar gas has been steadily increasing with time.

8 
 8. The author's main point is that

A. there is actually very little mass in the form of dim, low-mass stars
B. Schmidt's model accords with the conventional view on local unseen matter
C. although Schmidt's model accords with observational data, it is based on an improbable assumption
D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars
E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun

arpan7 · Answer

1. E (given in the last paragraph): " The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, "
2. E (The author mentions this is the conventional belief in the first paragraph but doubts on its credibility. Also he propose and alternative explanation with observed facts in the rest of the passage)
3. C (If the porportion of smaller stars wrt to large stars remain constant, then oxygen release would be at a constant rate.)
4. A (Last Line)
5. C (Given in 2nd paragraph): " Although the formation of massive stars am does not predominate at present in the solar neighborhood it may well have been more important in the past, me amount of interstellar gas and the rate of star formation were greater. "
6. D (Last line)
7. B (If oxygen increase was at a steady rate, its supply would also be in a steady rate. Hence their origin i.e. high mass stars would also form in a steady manner.)
8. D (The passage is regarding what comprises the unseen matter in the solar neighbourhood. The author gives 2 theories and clearly states that the 2nd one seems far more credible)

YogeshBardia · Answer

For Q1, from " The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe " in the passage we can choose E.

Q2. from the first paragraph we get the possibility of smaller starts constituting thw weight in the neighbourhood but later on we kind of question this probability with some evidence and later found studies.

Q3. from the 3rd para,  " A model for the content and evolution of the solar neighborhood can readily be constructed in which all the unseen mass is accounted for as remnants. "  we get  A.

Q4. From the last lines of the 3rd para where we get the info about his theory " It is interesting that, although Schmidt's model was devised to account for the data on element abundances in star s", we get A.

Q5. This is kinda tricky, we cant go with option-A as we already know that the oxygen is increasing slowly but definitely and so we can't have more oxygen at the beginning. For option-B ,from studies we go that There were more massive planets and less smaller dwarfs and so after some time the no. of dwarfs should increase, because if we had more massive planets we would have a constant increasing rate of oxygen too. For option-C , we cannot have interstellar gas until the massive stars explode into the supernova and we learned that we had more oxygen because of massive planets, so more massive planets = less supernovas. For D, I am not sure there is anything that poses a question, but it could be a good possibility that there were more stellar remnants. Finnally for E, I dont think the no. of dwarfs would go down, like the existed, but now they stopped existing? The no. can go up and that would prove that option to be wrong. Hence D in my opinion. (Please correct me if I am wrong anywhere, that would help me learn.)

Q6. from this, " It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass ." we can choose D.

Q7. If the amount of oxygen generation is steady, we already  know that it has something to do with massive stars, and so we can go for B. C is kinda similar to this as well, but it says that the rate of massive stars forming is increasing and so the rate of oxygen formation should increase too, but we know it stays constant or steady so we opt for B here.

Q8. This was a tough one for me. I found more thn one options to be right. For A, it is right but it is not the main point of the passage, so I think we can just ignore it. For B, although Schmidt's opinion matches with the general idea, we can not determine if it was the main issue, the author sort of just agreed with him subtly, in my opinion. For C, Now this is a true statement and we try to prove how his theory is less likely to happen(thus improbable) and this can be the answer. For D, this option also sounds true, because we can't see whats holding the mass in sun's vicinity and we are trying to find that out throughout the passage. For E, we never talk about the size of stars we would need to get stelar remanants from, so they can be smaller than sun too, we don't have any proof, and hence the last one's standing are C & D. I chose C. I don't know, I felt like we left the topic of something in sun's vicinity and focused more on these theories.

Thanks for considering this reply. Have a good day!

mayankdgmat · Answer

P1: Author introduce conventional theory which gives reason for unseen mass as brown dwarf, says this may be true but present more substantial evidence to undermine conventional theory

P2: Give alternate reason as "Remnants" for this unseen mass, which could have been release by explosion of massive starts in the past since the rate of star formation and amount of interstellar gas was more in the past. So Remnants from past may be an imp factor in the unseen mass

P3: Introduce a model that had same assumption (ratio of massive to smaller star formation was higher in past) as schmidt model. Schmidt model was devised for something else but has given observation for something else also

IMO answers as follows:

E
E
C
A
C
D
B
D

Explanations as follows:

1. The author states which of the following about oxygen in the universe?

A. Its presence is due largely to the formation of low-mass stars
Oxygen only form in massive stars. Hence wrong.

B. It is less abundant in the stars than it is in the interstellar gas.
It release from massive stars and mix into interstellar gas. No where it mentioned that is abundant in either of them. Wrong

C. Its presence is more difficult to explain than is the presence of unseen matter.
Relevant part of passage "between one-half and three-quarters of the mass in the solar neighborhood has not been identified with visible stars or gas." so gases are easily to explain than unseen matter. wrong

D. It appears to be less abundant than it would be if conventional theories of star formation were correct.
Conventional theory was all about brown dwarf, not oxygen. wrong

E. It increased rapidly in abundance during an earlier period and has since increased more slowly.
 Relevant part of passage is "Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas. The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe". Hence correct.

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is

Relevant portion of passage is "Although this possibility cannot be excluded, inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars."

A. well confirmed by observation
No, instead alternative explanation was given.

B. known to be incorrect
No, author says there is possibility.

C. indirectly supported by Schmidt's model
No, Schmidt model is not at all about brown dwarf

D. a recently proposed and interesting hypothesis
No, it is conventional theory.

E. possibly correct but more likely mistaken
 Yes, from above relevant portion of the passage.

3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red)

A. Most of the mass in the solar neighborhood is to the form of stellar remnants.
No, Model indeed in support of this conclusion.

B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed.
No, Model don't even discuss about brown dwarf stars

C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time.
 Yes it weakens because model is based on assumption "The model requires that the ratio of massive stars to smaller stars formed was higher at earlier times."

D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized.
No, It support the assumption of model.

E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now.
No. it indeed support the model.

4. According to the passage, Schmidt's model was originally created for which of the following purposes?

A. To explain the relative amounts of various chemicals present in stars
 Yes, relevant portion of passage "although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass."

B. To account for the unseen mass in the solar neighborhood
No, it explained it by chance.

C. To provide an alternative to the conventional theory of star formation
No, it explained it by chance

D. To describe the formation of stellar remnants
No, it devised for data on element abundance in stars.

E. To determine the relative rates at which high-mass and low-mass stars arc formed
No, it's about element of stars.

5. According to the passage which of the following was greater in the past?

A. The amount of oxygen in the universe
No, we only know about rate of increase.

B. The number of brown-dwarf stars in the universe
No, nothing mentioned about there change.

C. The amount of interstellar gas in the solar neighborhood
 Yes, relevant portion of passage "it may well have been more important in the past, me amount of interstellar gas and the rate of star formation were greater."

D. The number of stellar remnants in the solar neighborhood
No, we know only rate of star formation was higher.

E. The number of stars of very low mass in the vicinity of the Sun
No, cant conclude that from given information in passage

6. The author indicates that which of the following is an interesting feature of Schmidt's model?

A. It is much simpler than its rivals.
No, nothing mentioned in passage.

B. It does not rely on any unproven assumptions
No, it does rely on a assumption

C. It builds on well-established aspects of the conventional model of star formation.
No, have no relation with conventional theory.

D. It may be able to account for something else in addition to what it was created to explain.
 Yes, last line of passage suggest that.

E. It may allow for the prediction of future star formation as well as the explanation of past formation.
No, nothing about future mentioned

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

It is given in passage that oxygen abundance has increased rapidly first and then in slow rate. Accordingly massive star formation was higher early than in later stage. So here we have strong correlation bw oxygen formation and massive star formation. Steady formation means it is increasing linearly like straight line equation y=mx

A. There is less unseen mass in the solar neighborhood than had been believed.
Not necessarily, mass may have been same.

B. The rate at which high-mass stars have been formed has remained constant.
 Yes, as guessed in starting shows correlation bw both.

C. The rate of star formation has been increasing since the origin of the universe.
No, we cant conclude that since Oxygen only forms in massive stars.

D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars.
NO, it can be the case earlier also without steadily increase of oxygen.

E. The amount of interstellar gas has been steadily increasing with time.
No We are concerned about oxygen, there can be other interstellar gas like Helium also

8. The author's main point is that

A. there is actually very little mass in the form of dim, low-mass stars
No, author main purpose to show that rest of the mass may be form the remnant.

B. Schmidt's model accords with the conventional view on local unseen matter
No, first this statement is wrong since model doesn't support conventional view.

C. although Schmidt's model accords with observational data, it is based on an improbable assumption
No, model was discussed only later to prove ultimate point. Further we don't know assumption was improbable.

D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars
 Yes, exactly this is the main point

E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun
No, Remnants are result of collapse of stars is not the matter of concern here, author has presented this as fact.

Oppenheimer1945 · Answer

The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe

1. The author states which of the following about oxygen in the universe?

A. Its presence is due largely to the formation of low-mass stars (opposite).
B. It is less abundant in the stars than it is in the interstellar gas.(no such info given in P3)
C. Its presence is more difficult to explain than is the presence of unseen matter.(irrelavant)
D. It appears to be less abundant than it would be if conventional theories of star formation were correct.(not relevant)
 E. It increased rapidly in abundance during an earlier period and has since increased more slowly (as per passage).

Conventionally it has been assumed that this local unseen mass exists in the form of very dim, low-mass stars called brown dwarfs. Although this possibility cannot be excluded, inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars.
It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass.

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is
A. well confirmed by observation (author never confirms this hypothesis)
B. known to be incorrect (author never explicitly stated incorrecteness)
C. indirectly supported by Schmidt's model (author never confirms this hypothesis)
D. a recently proposed and interesting hypothesis (Not true)
 E. possibly correct but more likely mistaken (True)

A model for the content and evolution of the solar neighborhood can readily be constructed in which all the unseen mass is accounted for as remnants. The model requires that the ratio of massive stars to smaller stars formed was higher at earlier times. Like an earlier model proposed by Schmidt that makes the same assumption, this model can account for the variation with stellar age in the abundance of elements such as oxygen in nearby stars

3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red)

A. Most of the mass in the solar neighborhood is to the form of stellar remnants.(this neither supports nor weakens)
B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed.(how much fewer? nothing stated)
C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time.(this neither supports nor weakens)
D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized.(rate of abundance of oxygen is no way weakening)
 E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now. (gives the alternate reason)

4. According to the passage, Schmidt's model was originally created for which of the following purposes?
A. To explain the relative amounts of various chemicals present in stars (Model was not created to explain chemical nature of stars)
 B. To account for the unseen mass in the solar neighborhood (True) 
C. To provide an alternative to the conventional theory of star formation (alternate theory was not derieved from Schmidt's model)
D. To describe the formation of stellar remnants (Model was created to find the missing mass in solar neighbourhood)
E. To determine the relative rates at which high-mass and low-mass stars arc formed (Model was created to find the missing mass in solar neighbourhood)

it may well have been more important in the past, me amount of interstellar gas and the rate of star formation were greater.

5. According to the passage which of the following was greater in the past?

A. The amount of oxygen in the universe
B. The number of brown-dwarf stars in the universe
 C. The amount of interstellar gas in the solar neighborhood (True) 
D. The number of stellar remnants in the solar neighborhood
E. The number of stars of very low mass in the vicinity of the Sun

6. The author indicates that which of the following is an interesting feature of Schmidt's model?
  It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass.  
A. It is much simpler than its rivals.
B. It does not rely on any unproven assumptions
C. It builds on well-established aspects of the conventional model of star formation.
 D. It may be able to account for something else in addition to what it was created to explain.(True) 
E. It may allow for the prediction of future star formation as well as the explanation of past formation.

The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, can therefore be explained if the proportion of massive stars was higher at earlier times

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?
A. There is less unseen mass in the solar neighborhood than had been believed.
 B. The rate at which high-mass stars have been formed has remained constant. (True) 
C. The rate of star formation has been increasing since the origin of the universe.
D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars.
E. The amount of interstellar gas has been steadily increasing with time.

8. The author's main point is that
A. there is actually very little mass in the form of dim, low-mass stars (this is not stated as MP)
B. Schmidt's model accords with the conventional view on local unseen matter (this is a part of passage)
C. although Schmidt's model accords with observational data, it is based on an improbable assumption (improbable assumption of Schmidt's model is not the MP)
 D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars (This is what the author intends to say as main point) 
E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun (author never states that stellar remnants are result of collapse of stars as Main Point)

Sss678 · Answer

Q1. The author states which of the following about oxygen in the universe?

My answer is E).
 E. It increased rapidly in abundance during an earlier period and has since increased more slowly .
It is clearly mentioned in the third para of the passage -"The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, can therefore be explained if the proportion of massive stars was higher at earlier times."

A. Its presence is due largely to the formation of low-mass stars. 
It is completely against the information mentioned in the passage -"Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas."

B. It is less abundant in the stars than it is in the interstellar gas. 
It also goes opposite to the information mentione din the passage -"Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas."- According to it, oxygen is primarily present in the stars and spills over to the interstellar gas in case of supernova explosions.

C. Its presence is more difficult to explain than is the presence of unseen matter. 
Nowhere in the passage is it mentioned that presence of oxygen is difficult to explain than the resence of unseen matter.

D. It appears to be less abundant than it would be if conventional theories of star formation were correct. 
The following line -"The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, can therefore be explained if the proportion of massive stars was higher at earlier times."- gives some insights into the conventional theories of star formation and as per this, oxygen appears to be less abundant now  and not otherwise.

Q2.The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is 
My answer is E).
 E. possibly correct but more likely mistaken 
It is clear from the following line of the passage - "Although this possibility cannot be excluded, inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars."

A. well confirmed by observation 
It is not confirmed by any observation as per the author as mentioned in above line in the explanation of E).

B. known to be incorrect 
The author mentions "Although this possibility cannot be excluded,", so he is not stating that it is incorrect.

C. indirectly supported by Schmidt's model 
Nowhere in the passage is it linked to Schmidt's model.

D. a recently proposed and interesting hypothesis 
The author does not express any particular interest in this hypothesis but he is also not discrading the possibility as already seen in the line - "Although this possibility cannot be excluded, inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars."

Q3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red) 
My answer is C).
 C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time. 
The model described in lines 21-29 states that "all the unseen mass is accounted for as remnants. The model requires that the ratio of massive stars to smaller stars formed was higher at earlier times." So, it can be directly inferred that the number of smaller stars were leeser in proportion in earlier times as compared to now. Hence the statement - having constant proportion of smaller stars- goes directly against the model.

A. Most of the mass in the solar neighborhood is to the form of stellar remnants. 
It actually lends support to the model explaining the basis of unseen matter

B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed. 
There is no proper reference to the actual brown -dwarf stars in solar neighborhood. On the contrary , conventionally it has been assumed that there are more brown-dwarf stars.

D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized. 
It is mentioned in the passage , so it doesn't weaken the model.

E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now. 
It is also mentioned in the passage - "Although the formation of massive stars am does not predominate at present in the solar neighborhood it may well have been more important in the past, me amount of interstellar gas and the rate of star formation were greater." Though it doesn't provide direct linkage to the model but still it aligns with model and does not oppose it.

Q4. According to the passage, Schmidt's model was originally created for which of the following purposes? 
My answer is A)
 A. To explain the relative amounts of various chemicals present in stars 
It is mentioned in the following line of the passage - "It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars"

B. To account for the unseen mass in the solar neighborhood 
The original purpose of Schmidt's model was to account for the data on elements present in stars. and not account for the unseen mass in the solar neighborhood. The following line proves it - "It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars"

C. To provide an alternative to the conventional theory of star formation 
No, it doesn't provide any linkage to conventional theory of star formation.

D. To describe the formation of stellar remnants 
Though the Schmidt's model can be used to explain the stellar remnants but that is not its original purpose -"It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass."

E. To determine the relative rates at which high-mass and low-mass stars arc formed 
No, it is not the original purpose of the passage as seen in the line - "It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass."

Q5.According to the passage which of the following was greater in the past? 
My answer is C)
 C. The amount of interstellar gas in the solar neighborhood 
It is mentioned in the following line of the passage - "Although the formation of massive stars am does not predominate at present in the solar neighborhood it may well have been more important in the past, me amount of interstellar gas and the rate of star formation were greater."

A. The amount of oxygen in the universe 
The passage mentions the rise of oxygen was very rapid in early period and not the total amount in the universe.

B. The number of brown-dwarf stars in the universe 
There is no mention of higher number of brown-dwarf stars in the universe in the past period.

D. The number of stellar remnants in the solar neighborhood 
The passage actually explains that there were higher number of massive stars in the past which later converted to stellar remnants. So stellar remnants were not higher in the past.

E. The number of stars of very low mass in the vicinity of the Sun 
It is wrong since the passage mentions that the number of massive stars was higher in the vicinity of the sun in the past.

Q6. The author indicates that which of the following is an interesting feature of Schmidt's model? 
My answer is D).
 D. It may be able to account for something else in addition to what it was created to explain. 
It is clear from the line - "It is interesting that, although Schmidt's model was devised to account for the data on element abundances in stars, it also predicts enough mass in remnants to account for the local unseen mass." - that the original purpose of the Schmidt's model was to account for the different elements present in stars but the model might also be able to explain the cause of local unseen mass.

A. It is much simpler than its rivals. 
There is no mention of the simplicity of the model in the passage

B. It does not rely on any unproven assumptions 
The Schmidt's model relies on the assumption -"The model requires that the ratio of massive stars to smaller stars formed was higher at earlier times. Like an earlier model proposed by Schmidt that makes the same assumption," - however, the basis of this assumption is not clarified in the passage.

C. It builds on well-established aspects of the conventional model of star formation. 
The passage does not link conventional method of star formation to Schmidt's model

E. It may allow for the prediction of future star formation as well as the explanation of past formation. 
The passage doesn't mention anything as such.

Q7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage? 
My answer is A).
 A. There is less unseen mass in the solar neighborhood than had been believed. 
As per the passage  -"Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas. The rapid early rise and the later more gradual increase in the abundance of oxygen in the universe, which has been inferred from observations, can therefore be explained if the proportion of massive stars was higher at earlier times.". So if the oxygen abundance has been increasing at steady rate, then the number of massive stars in the solar neighborhood would have been almost constant and so does the low-mass stars. Hence, the unseen mass would have been lesser than expected now.

B. The rate at which high-mass stars have been formed has remained constant. 
As per the passage, if it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, then it can be inferred that the number of high mass stars might be constant ,not their formation.

C. The rate of star formation has been increasing since the origin of the universe. 
There is no direct expression involving rate of all star formation and  the rate of increase of oxygen.

D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars. 
This is the explanation for the current hypothesis, so the new discovery would have changed this notion .

E. The amount of interstellar gas has been steadily increasing with time. 
There is no direct linkage between the two concepts.

Q8. The author's main point is that 
My answer is D).
 D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars 
The entire passage concentrates on explaining the basis of unseen mass by linking the proportionof high-mas stars in the past to the increase of oxygen and hence the stellar remnants. So this is the central idea of the passage.

A. there is actually very little mass in the form of dim, low-mass stars 
It states opposite to whta is mentioned in the first para - Conventionally it has been assumed that this local unseen mass exists in the form of very dim, low-mass stars called brown dwarfs.

B. Schmidt's model accords with the conventional view on local unseen matter 
Schmidt's model is not the central idea of the passage. The author just takes help from Schmidt's model to explain the possible alternative explanation in the third para.

C. although Schmidt's model accords with observational data, it is based on an improbable assumption 
Schmidt's model is not the central idea of the passage. The author just takes help from Schmidt's model to explain the possible alternative explanation in the third para.

E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun 
The passage is not concerned with just the cause of creation of stellar remnants. It is one aspect of the passage, not the main point.

8Harshitsharma · Answer

Ultra crisp notes that I made:
P1: presents a possible solution that is unlikely to be true for an existing discrepancy
P2: An alternate possible solution is presented
P3: one model similar to existing model of Schmidt with the same assumption - explains the discrepancy, although made for a different purpose.

Pre-thought main point: Present possible solutions to a discrepancy and accept one of the solutions that is based on an assumption.

A. this point is proposed and then rejected in first para 
B. not supported anywhere - only stated that based on the assumption that in the past high mass stars > low mass stars, accounts for early rapid and then gradual increase in oxygen in the universe.
C. not discussed anywhere
D. conventional theories of star formation are not discussed as such in the passage 
 E. correct - this is stated as such in the middle portion of para 3     
 
   A. not stated 
 B. Not implied anywhere that is incorrect.
C. Schmidt's model is based on the assumption that in the past, high-mass stars# >> low-mass stars#. And also level of oxygen is still increasing gradually today which means high-mass stars# > low-mass stars# today. Opposite choice.
D. not recently proposed it was conventional 
 E. very weird choice of words for this answer choice but still the closest to information in para 1. "possible but mistaken"   
 
Pre-thinking: by attacking the assumption "in the past, high-mass star# - low-mass star# >> 0" we can weaken the support for the new model.
 A. strengthens
B. effect is not clear 
 C. if the proportion of smaller stars remained constant that would directly go against the assumption that "in the past, the ratio of high-mass stars# to low-mass stars# was higher than today" - it would further hinder the model's explanation of the oxygen level rising rapidly then increasing "gradually". 
 D. slowing of oxygen abundance would mean high-mass stars are decreasing at a faster rate than are formed. Meaning more gas is mixed with the interstellar. But still, the model will hold as such. 
 E. It is already stated as such in para 2 - doesn't do anything to the argument as such. INCORRECT  
  
 
 A. Yes, as stated in the last portion of para 3. 
 B. No
C. No
D. No
E. No     
 
 A. Not stated
B. Not stated 
 C. Yes, as stated in the middle of para 2. 
 D. Not stated
E. Not stated    
 
 A. Not stated
B. Actually, it does rely.
C. Nope it is based on an exclusive assumption. 
 D. Stated clearly in the last portion of para 3. 
 E. Not stated     
 
Pre-thinking: In para 3, it is stated that oxygen abundance is created by high-mass stars.

A. Nope 
 B. Nailed it. Steady oxy⬆️ steady high-mass stars creation. 
 C. only star formation increasing doesn't shed light on the total number of high-mass stars, whether this is increasing will determine oxygen level.
D. Nope
E. Nope 
 
 
 
The correct choice should fit in the "mold" set by the above main point without causing any unexpected trouble while covering all the major portions from the passage.

A. True, but only a grain of sand in the desert, as the passage is 
B. Doesn't need to accord: conventional view relies on brown dwarf abundance; we are making an assumption on the ratio of high-mass and low-mass stars from the past.
C. It is not an improbable assumption as per the passage. 
 D. True - this statement is also kind of specific, but at least covers the intro in para 1 stating the discrepancy, the para 2 stating this alternative explanation, and para 3 accepting the model justifying this explanation. 
 E. Bleh, random detail. Ignore immediately.

Can't wait to see how many I get right 🤩 and wrong😑 to learn from and get my target score😎

Anugmat740 · Answer

1. The author states which of the following about oxygen in the universe?

Refer to the line " The rapid early rise and the later more gradual increase in the abundance of oxygen  in the universe, which has been inferred from observations,"

A. Its presence is due largely to the formation of low-mass stars.
B. It is less abundant in the stars than it is in the interstellar gas. 
C. Its presence is more difficult to explain than is the presence of unseen matter.
D. It appears to be less abundant than it would be if conventional theories of star formation were correct.
 E. It increased rapidly in abundance during an earlier period and has since increased more slowly.

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is

Refer to the line " Although  this possibility cannot be excluded , inferences based on the ratio of visible low-mass to high-mass stars suggest that there is actually very little mass in unseen faint stars. " Possibility is correct but inference drawn is mistaken or may not be correct.

A. well confirmed by observation
B. known to be incorrect 
C. indirectly supported by Schmidt's model
D. a recently proposed and interesting hypothesis
 E. possibly correct but more likely mistaken

3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red)

The model requires that the ratio of massive stars to smaller stars formed  was higher  at earlier times.

A. Most of the mass in the solar neighborhood is to the form of stellar remnants.
B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed.
 C. The proportion of smaller stars formed in the solar neighborhood has  remained constant  through time.  Clearly weakens the above argument.
D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized.
E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now.

4. According to the passage, Schmidt's model was originally created for which of the following purposes?

The model is similar to the convention model and  is created to identify the unknown mass by creating remnants of the earlier generation of massive stars.

A. To explain the relative amounts of various chemicals present in stars
B. To account for the unseen mass in the solar neighborhood
C. To provide an alternative to the conventional theory of star formation
 D. To describe the formation of stellar remnants 
E. To determine the relative rates at which high-mass and low-mass stars arc formed

5. According to the passage which of the following was greater in the past? 
Refer to the line ...at present in the solar neighborhood it may well have been more important in the past,   the amount of interstellar gas   and the rate of star formation were greater.

A. The amount of oxygen in the universe
B. The number of brown-dwarf stars in the universe
 C. The amount of interstellar gas in the solar neighborhood 
D. The number of stellar remnants in the solar neighborhood
E. The number of stars of very low mass in the vicinity of the Sun

6. The author indicates that which of the following is an interesting feature of Schmidt's model? 
It is interesting that,  although Schmidt's model was devised to  account for the data on element abundances in stars,  it also predicts  enough mass in remnants to account for the local unseen mass.

A. It is much simpler than its rivals.
B. It does not rely on any unproven assumptions
C. It builds on well-established aspects of the conventional model of star formation.
 D. It may be able to account for something else in addition to what it was created to explain.  Correct the model also predicted one more finding other than it was created for.
E. It may allow for the prediction of future star formation as well as the explanation of past formation.

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

Refer to the line " Oxygen is produced only in massive stars and is mixed into the interstellar as when some of the star explode as supernovas.  Increasing Oxygen means  increase in massive stars formation and  increase in interstellar gas."

A. There is less unseen mass in the solar neighborhood than had been believed.
B. The rate at which high-mass stars have been formed has remained constant.
C. The rate of star formation has been increasing since the origin of the universe.
D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars.
 E. The amount of interstellar gas has been steadily increasing with time.

8. The author's main point is that

Author intitally mentions the conventional model mentions it's drawback, than another model which is the remnants of star model. This model is analogus to the model created by Schmidt observed similar theory that the unseen matter in solar neighbourhood may consist of remnants of very high mass stars.

A. there is actually very little mass in the form of dim, low-mass stars
B. Schmidt's model accords with the conventional view on local unseen matter
C. although Schmidt's model accords with observational data, it is based on an improbable assumption
 D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars 
E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun

missionmba2025 · Answer

1. The author states which of the following about oxygen in the universe?A. Its presence is due largely to the formation of low-mass stars. - Incorrect. The passage states that oxygen is produced only in massive stars.
B. It is less abundant in the stars than it is in the interstellar gas. - Not directly addressed in the passage.
C. Its presence is more difficult to explain than is the presence of unseen matter. - Incorrect. The passage doesn't compare the difficulty of explaining oxygen presence with that of unseen matter.
D. It appears to be less abundant than it would be if conventional theories of star formation were correct. - Incorrect. The passage discusses the increase in oxygen abundance over time, not its comparison with conventional theories of star formation.
E. It increased rapidly in abundance during an earlier period and has since increased more slowly -  Correct . The passage mentions the rapid early rise and the later more gradual increase in the abundance of oxygen in the universe.

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars isA. well confirmed by observation - Incorrect. The passage suggests that this idea may not be confirmed by observations.
B. known to be incorrect - Incorrect. The passage doesn't assert that the idea is definitely incorrect.
C. indirectly supported by Schmidt's model - Incorrect. The passage doesn't mention any support from Schmidt's model for this idea.
D. a recently proposed and interesting hypothesis - Incorrect. The passage doesn't mention the recency of the hypothesis.
E. possibly correct but more likely mistaken -  Correct . The passage implies uncertainty about the validity of this idea.

3. Which of the following, if true, would most weaken support for the model described in lines 21-29?

A. Most of the mass in the solar neighborhood is to the form of stellar remnants. - Incorrect. This strengthens support for the model.
B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed. - Incorrect. This might actually strengthen support for the model.
C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time. -  Correct . If this were true, it would weaken the model's assumption that the ratio of massive stars to smaller stars formed was higher at earlier times.
D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized. - Not directly relevant to the model described in the passage.
E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now. - Doesn't directly weaken the support for the model described in lines 21-29.

4. According to the passage, Schmidt's model was originally created for which of the following purposes?

A. To explain the relative amounts of various chemicals present in stars -  Correct . Refer line " Schmidt's model was devised to account for the data on element abundances in stars ,"
B. To account for the unseen mass in the solar neighborhood - Incorrect. Schmidt's model is mentioned as an alternative model, but not specifically created for this purpose.
C. To provide an alternative to the conventional theory of star formation - Incorrect. Schmidt's model is presented as an alternative explanation for the data on element abundances in stars.
D. To describe the formation of stellar remnants - Incorrect. Schmidt's model doesn't focus on the formation of stellar remnants.
E. To determine the relative rates at which high-mass and low-mass stars are formed - Incorrect.

5. According to the passage which of the following was greater in the past?A. The amount of oxygen in the universe -  Correct . The passage mentions the rapid early rise in the abundance of oxygen.
B. The number of brown-dwarf stars in the universe - Incorrect. Brown-dwarf stars are not discussed in the context of being greater in the past.
C. The amount of interstellar gas in the solar neighborhood - Incorrect. The passage discusses the possibility of interstellar gas being greater in the past, not its presence in the entire universe.
D. The number of stellar remnants in the solar neighborhood - Correct. The passage suggests that remnants of earlier generations of massive stars may have been more important in the past.
E. The number of stars of very low mass in the vicinity of the Sun - Incorrect. The passage doesn't discuss the number of low-mass stars in the past.

6. The author indicates that which of the following is an interesting feature of Schmidt's model?A. It is much simpler than its rivals. - Not mentioned in the passage.
B. It does not rely on any unproven assumptions - Not explicitly mentioned in the passage.
C. It builds on well-established aspects of the conventional model of star formation. - Incorrect. Schmidt's model is mentioned as an alternative to the conventional model.
D. It may be able to account for something else in addition to what it was created to explain. -  Correct .
The passage mentions that Schmidt's model predicts enough mass in remnants to account for the local unseen mass, in addition to its original purpose of explaining data on element abundances in stars.
E. It may allow for the prediction of future star formation as well as the explanation of past formation. - Not mentioned in the passage.

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

A. There is less unseen mass in the solar neighborhood than had been believed. - Not directly supported by the passage.
B. The rate at which high-mass stars have been formed has remained constant. -  Correct . This aligns with the idea that the proportion of massive stars was higher at earlier times.
C. The rate of star formation has been increasing since the origin of the universe. - Not directly supported by the passage.
D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars. - Not directly supported by the passage.
E. The amount of interstellar gas has been steadily increasing with time. - Not directly supported by the passage.

8. The author's main point is thatA. there is actually very little mass in the form of dim, low-mass stars - Incorrect. While the passage discusses the possibility of unseen mass not being in the form of brown dwarfs, it doesn't assert the absence of low-mass stars.
B. Schmidt's model accords with the conventional view on local unseen matter - Incorrect. Schmidt's model is presented as an alternative to conventional views.
C. although Schmidt's model accords with observational data, it is based on an improbable assumption - Incorrect. The passage doesn't suggest that Schmidt's model is based on an improbable assumption.
D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars -  Correct . This aligns with the main point that stellar remnants could account for the unseen mass.
E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun - Incorrect. This is mentioned in the passage but not as the main point. The main point is about stellar remnants accounting for the unseen mass.

Answers
1. E
2. E
3. C
4. A
5. A
6. D
7. B
8. D

Abhishek_007 · Answer

1. The author states which of the following about oxygen in the universe?

A. Its presence is due largely to the formation of low-mass stars. 
- Incorrect. The passage does not attribute the presence of oxygen to low-mass stars.

B. It is less abundant in the stars than it is in the interstellar gas. 
- Incorrect. The passage does not make a direct comparison between the abundance of oxygen in stars and interstellar gas.

C. Its presence is more difficult to explain than is the presence of unseen matter. 
- Incorrect. The passage does not suggest that the presence of oxygen is more difficult to explain than unseen matter.

D. It appears to be less abundant than it would be if conventional theories of star formation were correct. 
- Incorrect. The passage does not directly compare the abundance of oxygen to conventional theories of star formation.

E. It increased rapidly in abundance during an earlier period and has since increased more slowly. 
  - Correct. The passage mentions,   
 
    This option accurately reflects the information in the passage about the changing abundance of oxygen.

---

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is

A. well confirmed by observation 
- Incorrect. This is incorrect as the passage mentions that inferences based on star ratios suggest there is little mass in unseen faint stars, casting doubt on the idea of brown-dwarf stars being the main source of unseen mass.

B. known to be incorrect 
- Incorrect. This is too strong of a statement as the passage does not outright dismiss the idea of brown dwarfs but rather suggests it may not be the primary source of unseen mass.

C. indirectly supported by Schmidt's model 
- Incorrect. This is incorrect as Schmidt's model does not directly support the idea of brown-dwarf stars being the main source of unseen mass; instead, it focuses on stellar remnants.

D. a recently proposed and interesting hypothesis 
- Incorrect. This is incorrect as the passage does not indicate that this idea is recent or particularly interesting; it simply presents it as a possibility alongside other explanations.

E. possibly correct but more likely mistaken 
  - Correct.  The passage states,   
 
   indicating that the idea of mass in the form of brown-dwarf stars is a possibility but not necessarily the most likely one.

---

3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red)

A. Most of the mass in the solar neighborhood is to the form of stellar remnants. 
- Incorrect. This statement is actually consistent with the model's assumption that all unseen mass can be accounted for as remnants. It does not weaken support for the model.

B. There are fewer brown-dwarf stars in the solar neighborhood than has conventionally been assumed. 
- Incorrect. This statement does not directly address the model's assumption about the ratio of massive stars to smaller stars at earlier times. It is not relevant to the model's key assumption and therefore does not weaken the support for the model.

C. The proportion of smaller stars formed in the solar neighborhood has remained constant through time.  
   - Correct. This statement directly challenges the model's assumption that the ratio of massive stars to smaller stars was higher at earlier times. If the proportion of smaller stars remained constant, it contradicts the model's premise and weakens its support.

D. The increase in the abundance of oxygen, though rapid in the distant past, is slowing at a greater rate than has been realized. 
- Incorrect. This statement addresses the rate of change in oxygen abundance but does not directly challenge the model's assumption about the ratio of massive to smaller stars. It is not relevant to the key assumption of the model.

E. The amount of interstellar gas in the solar neighborhood was much greater during the early period of the universe than it is now. 
- Incorrect. While this statement provides information about interstellar gas, it does not directly impact the model's assumption about the ratio of massive stars to smaller stars at earlier times. It is not addressing the core premise of the model.

---

4. According to the passage, Schmidt's model was originally created for which of the following purposes?

A. To explain the relative amounts of various chemicals present in stars  
   - Correct. The relevant part of the passage is:   
 
   The passage indicats that the primary purpose of Schmidt's model was to explain the relative amounts of various chemicals, particularly elements like oxygen.

B. To account for the unseen mass in the solar neighborhood 
- Incorrect. The passage doesn't attribute Schmidt's model to explaining unseen mass.

C. To provide an alternative to the conventional theory of star formation 
- Incorrect. While Schmidt's model may be an alternative, it was created to explain element abundances.

D. To describe the formation of stellar remnants 
- Incorrect. The passage doesn't mention Schmidt's model being created to describe the formation of remnants.

E. To determine the relative rates at which high-mass and low-mass stars arc formed 
- Incorrect. The passage doesn't attribute Schmidt's model to determining rates of star formation.

---

5. According to the passage which of the following was greater in the past?

A. The amount of oxygen in the universe 
- Incorrect. The passage doesn't make a direct comparison of the amount of oxygen to interstellar gas.

B. The number of brown-dwarf stars in the universe 
- Incorrect. The passage doesn't discuss the number of brown-dwarf stars in the universe.

C. The amount of interstellar gas in the solar neighborhood  
   - Correct. The passage suggests that remnants of earlier generations of massive stars contribute to the total mass in the solar neighborhood, and this was more significant in the past when the amount of interstellar gas and the rate of star formation were greater.

D. The number of stellar remnants in the solar neighborhood 
- Incorrect. While remnants contribute to mass, the passage doesn't directly compare their numbers to the past.

E. The number of stars of very low mass in the vicinity of the Sun 
- Incorrect. The passage doesn't discuss the number of low-mass stars in the vicinity of the Sun.

---

6. The author indicates that which of the following is an interesting feature of Schmidt's model?

A. It is much simpler than its rivals. 
- Incorrect. The passage doesn't discuss the simplicity of Schmidt's model in comparison to others.​​​​​​​

B. It does not rely on any unproven assumptions 
- Incorrect. The passage doesn't make claims about the model not relying on unproven assumptions.​​​​​​​

C. It builds on well-established aspects of the conventional model of star formation. 
- Incorrect. The passage doesn't state that Schmidt's model builds on conventional aspects.​​​​​​​

D. It may be able to account for something else in addition to what it was created to explain.  
   - Correct. The passage mentions that Schmidt's model, while created to account for element abundances, also predicts enough mass in remnants to account for local unseen mass. This indicates an interesting additional feature of the model.

E. It may allow for the prediction of future star formation as well as the explanation of past formation. 
- Incorrect. The passage doesn't discuss the predictive capabilities of Schmidt's model.

---

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

A. There is less unseen mass in the solar neighborhood than had been believed. 
- Incorrect. The passage doesn't connect oxygen abundance to the belief in unseen mass.​​​​​​​

B. The rate at which high-mass stars have been formed has remained constant. 
- Incorrect. The passage doesn't discuss the constancy of the rate of high-mass star formation.​​​​​​​

C. The rate of star formation has been increasing since the origin of the universe.  
   - Correct. The passage suggests that the variation in the abundance of elements like oxygen can be explained by the proportion of massive stars being higher at earlier times. A steady increase in oxygen abundance supports the idea that the rate of star formation has been increasing.

D. Most of the unseen mass in the solar neighborhood is due to the collapse of very massive stars. 
- Incorrect. The passage connects unseen mass to remnants but doesn't directly tie it to the rate of star formation.​​​​​​​

E. The amount of interstellar gas has been steadily increasing with time. 
- Incorrect. The passage doesn't discuss the trend of interstellar gas increasing with time.

---

8. The author's main point is that

A. there is actually very little mass in the form of dim, low-mass stars 
- Incorrect. The passage doesn't focus on the mass of dim, low-mass stars.​​​​​​​

B. Schmidt's model accords with the conventional view on local unseen matter 
- Incorrect. The passage mentions Schmidt's model as an alternative to conventional views.​​​​​​​

C. although Schmidt's model accords with observational data, it is based on an improbable assumption 
- Incorrect. The passage doesn't characterize Schmidt's model as being based on an improbable assumption.​​​​​​​

D. the unseen matter in the solar neighborhood may well consist of the remnants of very high-mass stars 
  - Correct. The passage concludes with,    
 
    This suggests that remnants of very high-mass stars could account for the unseen mass in the solar neighborhood.​​​​​​​

E. stellar remnants are probably the result of the collapse of stars at least ten times as massive as the Sun 
- Incorrect. While the passage mentions remnants from massive stars, it doesn't specify the size as ten times the mass of the Sun.

Sajjad1994 · Answer

Official Explanation

1. The author states which of the following about oxygen in the universe?

Explanation

The passage discusses the abundance of oxygen in the universe and how it relates to the formation of stars, particularly massive stars. According to the passage:
 
  Oxygen Production:  Oxygen is produced only in massive stars. 
  Supernova Explosions:  Oxygen is mixed into the interstellar gas when some of these massive stars explode as supernovas. 
  Variation with Stellar Age:  The abundance of oxygen in nearby stars varies with stellar age. The passage mentions a rapid early rise and a later more gradual increase in the abundance of oxygen in the universe.  
Therefore, the correct statement about oxygen in the universe is that it increased rapidly in abundance during an earlier period and has since increased more slowly. This aligns with  option E.

Answer: E

Sajjad1994 · Answer

Official Explanation

2. The author implies that the idea that much of the mass in the solar neighborhood is in the form of brown-dwarf stars is

Explanation

A.  The passage does not provide evidence that the idea of much of the mass being in the form of brown-dwarf stars is well confirmed by observation. In fact, it introduces doubts about this assumption.

B.  The passage does not state that the idea of much of the mass being in the form of brown-dwarf stars is known to be incorrect. It raises questions about this assumption but doesn't make a definitive statement.

C.  This is partially correct.

D.  The passage does not provide information about the recency of the proposal regarding brown-dwarf stars. It mentions that the conventional assumption is that the unseen mass is in the form of brown dwarfs but does not characterize it as recently proposed.

E.   This is a reasonable interpretation based on the passage. The author introduces an alternative explanation involving stellar remnants and suggests that the conventional assumption about brown dwarfs may be mistaken. This option captures the uncertainty and doubt expressed in the passage regarding the assumption about brown dwarfs.

In summary,  option E  is correct because it aligns with the passage's tone of skepticism and presents the idea of brown-dwarf stars as possibly correct but more likely mistaken.  Options A, B,  and  D  are incorrect because they make stronger or unsupported statements, and  option C  is incorrect as it misinterprets the relationship between Schmidt's model and the brown-dwarf star hypothesis.

Answer: E

Sajjad1994 · Answer

Official Explanation

3. Which of the following, if true, would most weaken support for the model described in lines 21-29? (Text in Red)

Explanation

A.  supports the model's proposal rather than weakening it. If most of the mass is in the form of stellar remnants, it aligns with the model's explanation.

B.  Does not necessarily weaken the model. The model focuses on stellar remnants, not brown dwarfs, and even if there are fewer brown dwarfs, it doesn't directly challenge the main components of the model.

C.   This is the correct answer. The model requires a higher ratio of massive stars to smaller stars at earlier times. If the proportion of smaller stars formed has remained constant, it challenges the model's assumption that this ratio was higher in the past.

D.  This partially weakens but is not better than  option C.

E.  This statement supports the model by suggesting that there was more interstellar gas in the past, which could have led to the formation of more massive stars. It does not weaken the support for the model.

In summary, option C is indeed the correct answer.

Answer: C

Sajjad1994 · Answer

Official Explanation

4. According to the passage, Schmidt's model was originally created for which of the following purposes?

Explanation

A.   This is the correct answer. The passage explicitly mentions that Schmidt's model was devised to account for the data on element abundances in stars. It explains how the model can be used to understand the variation in the abundance of elements like oxygen in nearby stars.

B.  This is not the primary purpose of Schmidt's model, according to the passage. While the model is used to construct a broader understanding of the solar neighborhood, its original purpose was to explain element abundances in stars.

C.  The passage does not suggest that Schmidt's model was initially created as an alternative to the conventional theory of star formation. Schmidt's model shares the assumption with an earlier model mentioned in the passage, both proposing a higher ratio of massive stars to smaller stars at earlier times.

D.  Describing the formation of stellar remnants is a consequence of Schmidt's model, but the primary purpose, as stated in the passage, was to account for the data on element abundances in stars.

E.  The passage does not indicate that Schmidt's model was originally created to determine the relative rates at which high-mass and low-mass stars arc formed.

Answer: A

Sajjad1994 · Answer

Official Explanation      5. According to the passage which of the following was greater in the past?

Explanation

The passage mentions:  "Although the formation of massive stars does not predominate at present in the solar neighborhood, it may well have been more important in the past when the amount of interstellar gas and the rate of star formation were greater."

This indicates that in the past, the amount of interstellar gas in the solar neighborhood was greater. The passage suggests that this increased amount of interstellar gas in the past may have contributed to the formation of more massive stars, whose remnants are proposed to account for the unseen mass in the solar neighborhood.  C  is correct.

A.  The passage talks about the variation in the abundance of oxygen over time but does not explicitly state that the overall amount was greater in the past.

B.  The passage discusses doubts about the assumption that brown dwarfs account for the unseen mass but doesn't compare their number over time.

D.  While the passage discusses the importance of stellar remnants in the solar neighborhood, it doesn't explicitly compare their number over time.

E.  The passage questions the assumption of the existence of many brown dwarfs, but it doesn't provide a comparison of their number over time.

Answer: C

Sajjad1994 · Answer

Official Explanation

6. The author indicates that which of the following is an interesting feature of Schmidt's model ?

Explanation

A.  The passage does not provide information about the simplicity or complexity of Schmidt's model compared to rivals. Therefore, there is no indication in the passage to support this option. B.  The passage does not explicitly mention whether Schmidt's model relies on unproven assumptions or not. It does mention that Schmidt's model was devised to account for the data on element abundances in stars, but it does not provide details about any assumptions made.

C.  The passage does not provide information about whether Schmidt's model builds on well-established aspects of the conventional model of star formation. It mentions that Schmidt's model makes the same assumption as an earlier model, but it doesn't specify if this assumption aligns with well-established aspects of the conventional model.

D.   This is the correct answer. The passage explicitly states that Schmidt's model, created to account for the data on element abundances in stars, also predicts enough mass in remnants to account for the local unseen mass. It suggests that the model may be able to explain more than originally intended.

E.  The passage does not provide information about whether Schmidt's model allows for the prediction of future star formation. It focuses on the model's ability to explain the observed variation with stellar age in the abundance of elements such as oxygen.

In summary,  option D  is the correct answer based on the passage's indication that Schmidt's model may be able to account for something else (mass in remnants) in addition to its original purpose of explaining element abundances in stars.

Answer: D

Sajjad1994 · Answer

Official Explanation

7. If it were discovered that oxygen abundance has been increasing at a steady rate throughout the age of the universe, which of the following inferences would be most strongly supported by the passage?

Explanation

The passage suggests that the formation of massive stars does not predominate at present in the solar neighborhood but may have been more important in the past when the rate of star formation was greater. If oxygen abundance has been increasing steadily, it implies a consistent production of oxygen over time, which could be explained by a constant rate of formation of high-mass stars. Therefore,  option B  is correct.

A.  The passage doesn't provide a direct link between the rate of oxygen increase and the amount of unseen mass in the solar neighborhood. It primarily focuses on the contribution of massive stars and their remnants.

C.  The passage suggests that star formation might have been more significant in the past due to a greater amount of interstellar gas. However, a steady increase in oxygen abundance does not necessarily imply a continuous increase in the rate of star formation.

D.  The passage mentions massive stars, but it doesn't specify that they are  "very massive."  The term  "massive"  could encompass a range of star sizes. Also, the increase in oxygen abundance doesn't explicitly support the idea that the unseen mass is specifically due to the collapse of very massive stars.

E.  The passage suggests that in the past, the amount of interstellar gas might have been greater, but it doesn't necessarily support a steady increase in interstellar gas throughout the entire age of the universe.

In summary, based on the information in the passage,  option B  is the most strongly supported inference.

Answer: B

Sajjad1994 · Answer

Official Explanation

8. The author's main point is that

Explanation

The passage argues that a significant portion of the unseen mass in the solar neighborhood might be explained by stellar remnants, particularly those left behind by stars at least ten times as massive as the Sun. The author supports this by suggesting that although the formation of massive stars doesn't predominate at present, it might have been more important in the past when the interstellar gas and star formation rates were greater. Remnants of earlier generations of massive stars could then contribute to the total mass in the solar neighborhood. This aligns with  option D.

A.  While the passage discusses the possibility that brown dwarfs might not account for the unseen mass, the main focus is on the alternative explanation of stellar remnants, particularly those from massive stars.

B.  The passage mentions that Schmidt's model, like an earlier model, assumes a higher ratio of massive stars to smaller stars at earlier times. However, the primary focus is on the potential contribution of stellar remnants to the unseen mass, not the agreement with the conventional view.

C.  The passage doesn't suggest that Schmidt's model is based on an improbable assumption. In fact, it indicates that both Schmidt's model and an earlier model share the assumption of a higher ratio of massive stars to smaller stars at earlier times.

E.  While the passage supports the idea that stellar remnants are the result of the collapse of massive stars, it doesn't explicitly state the specific mass threshold of ten times as massive as the Sun. The focus is more on the potential contribution of remnants to the unseen mass.

Answer: D

VerbalBot · Answer

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Analysis of the motions of stars in the vicinity of the Sun indicates

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