Stellar objects are dynamic systems involving a symbiotic relationship

Question

Stellar objects are dynamic systems involving a symbiotic relationship between matter and radiation. Thermonuclear fusion, the thermally-induced combining of nuclei as they tunnel through the Coulomb barrier, is responsible for supporting stars against gravitational contraction and the ultimate fate of a star depends upon its remaining mass once thermonuclear fusion can no longer provide the pressure required to counteract gravity.

In a live star, the hot center allows hydrogen to fuse into helium, but once the core has burned all available hydrogen, it will contract until another source of support becomes available. If the star is massive enough, as the core contracts and heats, transforming gravitational energy into kinetic energy, it begins burning helium ashes and producing iron, the most stable of nuclei. This thermonuclear burning continues until it produces an iron core at the heart of the star. The three final forms a star can hold are a white dwarf, a neutron star, or a black hole.

Our Sun will expand and expel most of its outer matter to create a planetary nebula. The remaining core will cool, and at
some point the Fermi pressure of the degenerate electrons will become sufficient to counteract the gravitational pressure; the sun will stabilize. The result will be a relatively cold compact object: a white dwarf star.

In stark contrast, neutron stars result from one of the most cataclysmic events in the universe, the death of a star with a mass much greater than that of our Sun. Electrons in these stars behave ultra-relativistically and hydrostatic equilibrium becomes impossible to achieve. During the collapse of the core, a supernovae shock develops ejecting most of the mass of the star into interstellar space and leaving behind an extremely dense core: the neutron star.

As a star collapses into a neutron core, it begins to lose mass in the form of neutrino radiation. The loss of mass relieves sustaining pressure provided by the core and if that pressure is reduced to the limit beyond which it can not prevent gravitational contraction, the star will collapse into an object of zero radius: a black hole.   1 
 1. According to the passage which of the following is not true of all stars?

(A) They generated helium as a product of thermonuclear fusion.
(B) They rely on internally produced pressures to counteract the effects of gravity on their own mass.
(C) They possess cores hot enough to combine nuclei. 
(D) They eventually produce iron cores through thermonuclear burning.
(E) Their ultimate form is related to the mass they possess as they begin to die.

2 
 2. The primary purpose of the passage is to

(A) present a commonplace idea and its inaccuracies 
(B) explore the implications of a finding
(C) propose a hypothesis for unexplained observations 
(D) analyze a frequent source of misunderstanding
(E) describe a process and its outcomes

3 
 3. Which of the following can most logically be inferred from the passage?

(A) Our Sun has fused the majority of the hydrogen contained within it.
(B) A supernovae shock precedes the formation of a black hole. 
(C) Neutrino radiation is caused by ultra-relativistically electrons.
(D) Fermi pressure is brought about by the gravitational pressure of a collapsing star.
(E) A white dwarf star is incapable of melting the tails of passing comets.

QUESTION-1
The second sentence of paragraph two states that stars produce iron cores only if they have sufficient mass.
Thus, not all stars produce iron cores. Choice D is correct.

QUESTION-2
The passage describes a process that begins "once thermonuclear fusion can no longer provide the pressure required to counteract gravity" in a star. Specifically, the passage describes the three possible outcomes for stars as they "die."
Thus, choice E is the best choice.

QUESTION-3
Paragraph five indicates that when a star collapses into a neutron stars it may continue to collapse further into a black hole. Since paragraph four states that neutron star formation is preceded by a supernovae shock, black hole formation must therefore also be preceded by a supernovae shock. Choice B is correct.

Zatan99 · Answer

Hi there. I am not a verbal expert, but I want to practice myself. So I will try to explain my understand. Please help me fix if I am wrong in some points.

The first question ask about which one is not true of all stars. So from my understand, I have to understand the overall structure so that I can find the location where there are details that tell me about info of every stars, not just one type of stars. The structure of each paragraph will be like - Para 1&2: common characters of all stars - Para 3: white dwarf - Para 4: the neutron star - Para 5: black hole How I know it? - The last sentence of 2nd paragraph is "The three final forms a star can hold are a white dwarf, a neutron star, or a black hole." So I can think that OK after this they may tell about these 3 final form - And yes they tell about it in each paragraph! We can easily spot from the last word of each para 3&4&5 So now I know that I have to look into para 1&2 in order to get answer since these paragraphs talk about overall stars details. For me this question is hard, but OK, let's look at the choices 1. According to the passage which of the following is not true of all stars? (A) They generated helium as a product of thermonuclear fusion. So it basically says that Thermo -> Helium. In para 2, it says "In a live star, the hot center allows hydrogen to fuse into helium," so it means that the star makes helium. I'm not sure about thermo thing, so it is not 100% right but not wrong either. So I keep it but partly eliminate. (B) They rely on internally produced pressures to counteract the effects of gravity on their own mass. So it says that pressure something counteract the gravity. In para 1, it talks about thermo that support stars against gravity, and pressure counteract gravity. So for me I eliminate this choice since it is mentioned. Eliminate. (C) They possess cores hot enough to combine nuclei. it does say about "Thermonuclear fusion, the thermally-induced combining of nuclei " which has combine nuclei? So I am not sure but think that this not gonna be a right answer.

(D) They eventually produce iron cores through thermonuclear burning. So my understand is that it says that the stars produce ironcore through thermo, which mean that both ironcore and thermo have the action in the same moment. At first I see that, OK, it talks about iron cores. But when I look closely, it says "This thermonuclear burning continues until it produces an iron core at the heart of the star. ". This means that thermo thing continues until it the ironcore is produced, which means that it is not happened at the same time. For me, this choice is very convincing. (E) Their ultimate form is related to the mass they possess as they begin to die OK. This choice is stated very clear in the sentence "the ultimate fate of a star depends upon its remaining mass". Eliminate. So now I got A,C, and D left. But in A,C though i cant find the right explanation, I think that with my current resource, I could eliminate the choices. But in D, it is obvious that the info is not correct. So D is the right answer. On the second question, this one looks a lot more easy to me. 2. The primary purpose of the passage is to (A) present a commonplace idea and its inaccuracies ; ok it does present idea. But does it mention about inaccuracy? NO. so Eliminate . (B) explore the implications of a finding ; Firstly, it doesnt say that this is a "finding". And it is not "implication", just more of normal information. Eliminate. (C) propose a hypothesis for unexplained observations ; No hypothesis at all. And no mention about unexplain. Eliminate. (D) analyze a frequent source of misunderstanding ; Didn't see any words talk about "misunderstanding" or "frequent source" Eliminate. (E) describe a process and its outcomes ; It says about process of many things (when it says that something is like this, then it will...,then it begins...,then it continues... For me these are clues of "process"). And the "outcomes" are obvious. It talks about 3 outcomes and do describe each in para 3&4&5. So YES we choose this. PS. in the first question is kind of tough for me. Any experts please give suggestions.

Nipungupta9081 · Answer

Took me around 6 minutes - the language is interesting , i still need to catch up on this.

Well here are the explanations

Para 1 : Talks about thermonuclear fusion and how stars are formed. 
Para 2 : Talks about how hydrogen to fuse into helium and 3 stars are formed.
Para 3 : white dwarf star is formed 
Para 4 : the neutron star.
Para 5 : The Black Hole.

Q1. According to the passage which of the following is not true of all stars?

Answer : (D) They eventually produce iron cores through thermonuclear burning -  This thermonuclear burning continues until it produces an iron core at the heart of the star . - Specifically mentioned in the passage.

Q2. The primary purpose of the passage is to

Answer :  (E) describe a process and its outcomes  - Attached the summary in the starting .

Q3. Which of the following can most logically be inferred from the passage?

Answer :  (B) A supernovae shock precedes the formation of a black hole.  -  Para 4  " During the collapse of the core, a supernovae shock develops ejecting most of the mass of the star into interstellar space and leaving behind an extremely dense core: the neutron star. " and then  followed by Para 5  - As a star collapses into a neutron core, it begins to lose mass in the form of neutrino radiation. The loss of mass relieves sustaining pressure provided by the core and if that pressure is reduced to the limit beyond which it can not prevent gravitational contraction, the star will collapse into an object of zero radius: a black hole.

bM22 · Answer

1. According to the passage which of the following is not true of  all stars ?

(A) They generated helium as a product of thermonuclear fusion.
(B) They rely on internally produced pressures to counteract the effects of gravity on their own mass.
(C) They possess cores hot enough to combine nuclei.
 (D) They eventually produce iron cores through thermonuclear burning.
 (E) Their ultimate form is related to the mass they possess as they begin to die.

Explanation: Consider the lines: " If the star is massive enough , as the core contracts and heats, transforming gravitational energy into kinetic energy, it begins burning helium ashes and producing iron, the most stable of nuclei.  This thermonuclear burning continues until it produces an iron core at the heart of the star. ." We can infer that D is not true for all stars, whereas other options mentioned are relevant for all the stars.

2. The primary purpose of the passage is to

(A) present a commonplace idea and its inaccuracies
(B) explore the implications of a finding
(C) propose a hypothesis for unexplained observations
(D) analyze a frequent source of misunderstanding
 (E) describe a process and its outcomes

Explanation: Throughout the passage we see that author describing the Thermonuclear fusion and how it leads to the three final forms a star, thus implying that option E is the correct choice. Other options are incorrect as author is not presenting any idea or an hypothesis and mentioning their inaccuracies or implications. He is simply talking about a process and how it leads to the formation of white dwarf, a neutron star, or a black hole.

3. Which of the following can most logically be inferred from the passage?

(A) Our Sun has fused the majority of the hydrogen contained within it.
 (B) A supernovae shock precedes the formation of a black hole.
 (C) Neutrino radiation is caused by ultra-relativistically electrons.
(D) Fermi pressure is brought about by the gravitational pressure of a collapsing star.
(E) A white dwarf star is incapable of melting the tails of passing comets.

Explanation: can be inferred from the lines: "a supernovae shock develops ejecting most of the mass of the star into interstellar space and leaving behind an extremely dense core: the neutron star. As a star collapses into a neutron core,.......the star will collapse into an object of zero radius: a black hole.", implying that a supernovae shock precedes the formation of a black hole. Options A, D and E cannot be inferred as they are not mentioned in the passage. Option C is a little tricky as it is present in the passage, and can be considered as a trap answer, but is not correct. From the passage, we know that when the core collapses, a supernovae shock develops ejecting most of the mass of the star into interstellar space and leaving behind an extremely dense core: the neutron star. Now, what's mentioned next is : "As a star collapses into a neutron core, it begins to lose mass in the form of neutrino radiation.", thus we cannot if Neutrino radiation is caused by the ultra-relativistically electrons.

Thanks.

TheAdmissionHub · Answer

Paragraph 1 — What the author does / talks about: 
The author introduces the relationship between matter, radiation, and gravity in stars. The paragraph explains that thermonuclear fusion provides the pressure needed to prevent stars from collapsing and that the final state of a star depends on its remaining mass after fusion stops.
 Short summary: 
 The paragraph explains why fusion is essential for a star’s stability and introduces the idea that a star’s mass determines its final fate.
 
 Paragraph 2 — What the author does / talks about: 
The author explains the life cycle of a star after it uses up its hydrogen fuel. The paragraph describes how a massive star continues fusing heavier elements until it creates an iron core, and it introduces the three possible final states of a star: white dwarf, neutron star, or black hole.
 Short summary: 
 The paragraph describes how stars evolve after hydrogen depletion and identifies their three possible end states.
 
 Paragraph 3 — What the author does / talks about: 
The author focuses on the future of our Sun and explains that it will become a white dwarf. The paragraph describes how the Sun will lose its outer layers and how electron pressure will eventually stabilize the remaining core.
 Short summary: 
 The paragraph explains the process by which a Sun-like star becomes a white dwarf.
 
 Paragraph 4 — What the author does / talks about: 
The author contrasts white dwarfs with neutron stars and explains that neutron stars form from the violent collapse of much more massive stars. The paragraph describes how a supernova ejects most of the star’s material while leaving behind an extremely dense core.
 Short summary: 
 The paragraph explains the formation of neutron stars through massive stellar explosions.
 Paragraph 5 — What the author does / talks about: 
The author explains the final stage of stellar collapse leading to a black hole. The paragraph describes how mass loss through neutrino radiation reduces the pressure supporting the star, allowing gravity to cause complete collapse.
 Short summary: 
 The paragraph explains how a collapsing star can become a black hole when gravity overwhelms all remaining pressure.
 
 1. Which of the following is NOT true of all stars? 
 (A) They generated helium as a product of thermonuclear fusion. 
  Wrong:  The passage says that in a live star, hydrogen fuses into helium. This describes stars in general, so this is true.
 (B) They rely on internally produced pressures to counteract the effects of gravity on their own mass. 
  Wrong:  The passage states that thermonuclear fusion provides pressure that supports stars against gravitational contraction. All stars need internal pressure to balance gravity.
 (C) They possess cores hot enough to combine nuclei. 
  Wrong:  Stars are defined by having hot cores where nuclear fusion can occur, so this is true.
 (D) They eventually produce iron cores through thermonuclear burning. 
   Correct:  
 This is  not true of all stars . The passage says that  massive stars  continue burning helium and heavier elements until they produce an iron core. A star like the Sun does not become massive enough to create an iron core; it becomes a white dwarf after exhausting its fuel.
 (E) Their ultimate form is related to the mass they possess as they begin to die. 
  Wrong:  The passage explicitly states that a star’s final fate depends on its remaining mass after fusion can no longer support it.

2. The primary purpose of the passage is to... 
 (A) Present a commonplace idea and its inaccuracies 
  Wrong:  The passage does not introduce a common belief and then correct mistakes. It simply explains how stars evolve.
 (B) Explore the implications of a finding 
  Wrong:  The passage does not discuss a specific discovery or research finding and its consequences.
 (C) Propose a hypothesis for unexplained observations 
  Wrong:  The author does not propose a new theory or attempt to explain something unknown.
 (D) Analyze a frequent source of misunderstanding 
  Wrong:   The passage does not focus on correcting misconceptions about stars.
 (E) Describe a process and its outcomes 
  Correct:  The passage describes the  process of stellar evolution : how stars burn fuel, lose stability, collapse, and eventually become white dwarfs, neutron stars, or black holes.

3. Which of the following can most logically be inferred from the passage? 
 (A) Our Sun has fused the majority of the hydrogen contained within it. 
  Correct:  The passage states that the Sun will eventually expand and expel its outer matter when it has exhausted its available hydrogen. Since the Sun is currently a live star and will eventually enter this stage, it can be inferred that it has already fused a large portion of its hydrogen.
 (B) A supernovae shock precedes the formation of a black hole. 
  Wrong:  The passage states that a supernova shock occurs during the formation of a neutron star, not necessarily before every black hole. A black hole forms later if the remaining core collapses further after losing supporting pressure.
 (C) Neutrino radiation is caused by ultra-relativistically electrons. 
  Wrong:  The passage mentions ultra-relativistic electrons in relation to neutron stars and separately discusses neutrino radiation during collapse. It does not state that electrons cause neutrino radiation.
 (D) Fermi pressure is brought about by the gravitational pressure of a collapsing star. 
  Wrong:  The passage explains that Fermi pressure from degenerate electrons counters gravitational pressure; it is not caused by gravity.
 (E) A white dwarf star is incapable of melting the tails of passing comets. 
  Wrong:  The passage does not discuss comets or the ability of white dwarfs to melt comet tails, so this cannot be inferred.

Stellar objects are dynamic systems involving a symbiotic relationship

Prep Toolkit

Top 5 GMAT Debrief Videos

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

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

Stellar objects are dynamic systems involving a symbiotic relationship

Prep Toolkit

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

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards