According to the passage, the lower regions of the Earth's mantle are characterized by
Julie-VJuly 9, 2019
Answer Explanations
Hello there!
I was wondering if someone could explain why A is the correct answer and how we can eliminate the wrong ones. I realized after I reviewed my answers that lines 40-41 states that earth's mantle is has roughly the same composition as meteorites, but when I was doing the question I thought the support was supposed to come from lines 28-34. Many thanks in advance for the help!
Replies
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Thanks for the question! (A) is correct, as you surmised, because of lines 40-41. These lines give us direct textual evidence suggesting that the composition of the lower regions of the Earth's mantle is similar to that of meteorites.
(B) is incorrect because we aren't told anywhere in the passage that the lower mantle is lacking elements found in rocks on the Earth's crust, only that it has elements that aren't found in rocks on the Earth's crust, such as iridium.
(C) is incorrect because we aren't told that the lower regions of the mantle are more stable than the upper regions. Indeed, we're told that the lowest layer of the Earth's mantle is unstable in line 27, though this still isn't compared to the upper regions.
(D) is incorrect because we're not told that there' a large amount of carbon dioxide in the lower regions of the Earth's mantle.
(E) is incorrect because the passage actually suggests the opposite in lines 30-31. When the bottom layer is heated and becomes less dense, it begins to escape upward, which would imply that the upper regions are generally lower density than the lower ones. Hope this helps!
Natalee-GeertsSeptember 1, 2020
I still don't understand why D is not correct based on the information in the second to last paragraph of the passage. It talks of increased amount of carbon dioxide (24) within the lower layers of the earth's mantle (27-28)
Natalee-GeertsSeptember 1, 2020
I still don't understand why D is not correct based on the information in the second to last paragraph of the passage. It talks of increased amount of carbon dioxide (24) within the lower layers of the earth's mantle (27-28)
