I have already explained Question 1.
3. It can be inferred from the passage that, if Fabian is correct, gas in the peripheral regions of a galaxy cluster
(A) streams outward into intergalactic space
(B) is hotter than gas in the central regions of the galaxy
(C) is composed primarily of gas left over from the big bang
(D) results in the creation of unusually large stars
(E) expands to increase the size of the galaxy
From the second para "Thus, the physicist Fabian reasoned that as intergalactic gas cools, the cooler gas shrinks inward toward the center of the galaxy. Meanwhile its place is taken by hotter intergalactic gas from farther out on the edge of the galaxy, which cools as it is compressed and flows into the galaxy."
From above, it it clear that gas in the external region is hotter than the gas in the central region. As gas cools down, it moves towards inner side of the galaxy.
The best option that summarizes above point is : (B) is hotter than gas in the central regions of the galaxy
5. According to the passage, Fabian believes that gas flowing into a central galaxy has which of the following characteristics?
(A) It is one-tenth hotter than it was in the outer regions of the galaxy cluster.
(B) It emits radiation with wavelengths that change as the gas moves toward the center of the galaxy.
(C) The total amount of radiation emitted diminishes as the gas cools.
(D) It loses 90 percent of its energy as it moves to the center of the galaxy.
(E) It condenses at a rate much slower than the rate of decrease in temperature as the gas flows inward.
From the 3rd para , "Because the strands of gas radiating from NGC 1275 are visible in optical photographs, Fabian suggested that such strands consisted not of gas blown out of the galaxy but of cooling flows of gas streaming inward. He noted that the wavelengths of the radiation emitted by a gas would changes as the gas cooled, so that as the gas flowed into the galaxy and became cooler, it would emit not x-rays, but visible light, like that which was captured in the photographs"
The lines above state that as gas cools down and moves towards the inner side of galaxy, the wavelength of the radiation would change
The option that summarizes above is : (B) It emits radiation with wavelengths that change as the gas moves toward the center of the galaxy.
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