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# The dark regions in the starry night sky are not pockets

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The dark regions in the starry night sky are not pockets  [#permalink]

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16 Aug 2019, 01:26
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Question 1
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72% (02:11) correct 28% (02:23) wrong

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Question 2
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36% (00:54) correct 64% (01:09) wrong

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Question 3
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Kudos for the right answer and explanation

The dark regions in the starry night sky are not pockets in the universe that are devoid of stars as had long been thought. Rather, they are dark because of interstellar dust that hides the stars behind it. Although its visual effect is so pronounced, dust is only a minor constituent of the material, extremely low in density, that lies between the stars. Dust accounts for about one percent of the total mass of interstellar matter. The rest is hydrogen and helium gas, with small amounts of other elements. The interstellar material, rather like terrestrial clouds, comes in all shapes and sizes. The average density of interstellar material in the vicinity of our Sun is 1,000 to 10,000 times less than the best terrestrial laboratory vacuum. It is only because of the enormous interstellar distances that so little material per unit of volume becomes so significant. Optical astronomy is most directly affected, for although interstellar gas is perfectly transparent, the dust is not.
1. According to the passage, which of the following is a direct perceptual consequence of interstellar dust?

(A) Some stars are rendered invisible to observers on Earth.
(B) Many visible stars are made to seem brighter than they really are.
(C) The presence of hydrogen and helium gas is revealed.
(D) The night sky appears dusty at all times to observers on Earth.
(E) The dust is conspicuously visible against a background of bright stars.

Spoiler: :: OA
A

2. It can be inferred from the passage that the density of interstellar material is

(A) higher where distances between the stars are shorter
(B) equal to that of interstellar dust
(C) unusually low in the vicinity of our Sun
(D) independent of the incidence of gaseous components
(E) not homogeneous throughout interstellar space

Spoiler: :: OA
E

3. It can be inferred from the passage that it is because space is so vast that

(A) little of the interstellar material in it seems substantial
(B) normal units of volume seem futile for measurements of density
(C) stars can be far enough from Earth to be obscured even by very sparsely distributed matter
(D) interstellar gases can, for all practical purposes, be regarded as transparent
(E) optical astronomy would be of little use even if no interstellar dust existed

Spoiler: :: OA
C

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Re: The dark regions in the starry night sky are not pockets  [#permalink]

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19 Aug 2019, 04:46
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All correct in 3 mins 45 seconds, including 1 min 45 seconds to read.

1. According to the passage, which of the following is a direct perceptual consequence of interstellar dust?

(A) Some stars are rendered invisible to observers on Earth. - Correct
The dark regions in the starry night sky are not pockets in the universe that are devoid of stars as had long been thought. Rather, they are dark because of interstellar dust that hides the stars behind it.

2. It can be inferred from the passage that the density of interstellar material is
(E) not homogeneous throughout interstellar space - Correct
The average density of interstellar material in the vicinity of our Sun is 1,000 to 10,000 times less than the best terrestrial laboratory vacuum. --> since the passage talks about average density, we can infer that the density is not homogeneous

3. It can be inferred from the passage that it is because space is so vast that
(C) stars can be far enough from Earth to be obscured even by very sparsely distributed matter - Correct
It is only because of the enormous interstellar distances that so little material per unit of volume becomes so significant. Optical astronomy is most directly affected, for although interstellar gas is perfectly transparent, the dust is not.
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Re: The dark regions in the starry night sky are not pockets  [#permalink]

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19 Aug 2019, 05:35
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carcass wrote:
3. It can be inferred from the passage that it is because space is so vast that

(A) little of the interstellar material in it seems substantial
(B) normal units of volume seem futile for measurements of density
(C) stars can be far enough from Earth to be obscured even by very sparsely distributed matter
(D) interstellar gases can, for all practical purposes, be regarded as transparent
(E) optical astronomy would be of little use even if no interstellar dust existed

Could someone tell me what is wrong in option A?

I chose A as it resembled the 2nd last sentence in the passage.
carcass wrote:
It is only because of the enormous interstellar distances that so little material per unit of volume becomes so significant.
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Re: The dark regions in the starry night sky are not pockets  [#permalink]

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19 Aug 2019, 12:11
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It is only because of the enormous interstellar distances that so little material per unit of volume becomes so significant.

(C) stars can be far enough from Earth to be obscured even by very sparsely distributed matter

What is sparsely, which means NOT so dense, to a long-distance the become significant in obscuring the stars

(A) little of the interstellar material in it seems substantial

It is not the same paraphrasing. Moreover, in C we talk about the matter + other material = Interstellar Material.

In A , on the other hand, we care about ONLY of matter

Hope is now more clear to you. The passage is short but nasty

Regards
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Re: The dark regions in the starry night sky are not pockets   [#permalink] 19 Aug 2019, 12:11
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