Eight percent of the Earth's crust is aluminum, and there are hundreds

Question

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Passage # 142, Date: 10-Jun-2020
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Eight percent of the Earth's crust is aluminum, and there are hundreds of aluminum-bearing minerals and vast quantities of the rocks that contain them. The best aluminum ore. is bauxite, defined as aggregates of aluminous minerals, more or less impure, in which aluminum is present as hydrated oxides. Bauxite is the richest of all those aluminous rocks that occur in large quantities, and it yields alumina, the intermediate product required for the production of aluminum. Alumina also occurs naturally as the mineral corundum, but corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum. Most of the many abundant nonbauxite aluminous minerals are silicates, and, like all silicate minerals, they are refractory, resistant to analysis, and extremely difficult to process. The aluminum silicates are therefore generally unsuitable alternatives to bauxite because considerably more energy is required to extract alumina from them.    1 
 C 
 1. The author implies that a mineral must either be or readily supply which of the following in order to be classified as an aluminum ore?

(A) An aggregate 
(B) Bauxite 
(C) Alumina 
(D) Corundum 
(E) An aluminum silicate

2 
 A 
 2. The passage supplies information for answering all of the following questions regarding aluminous minerals EXCEPT:

(A) What percentage of the aluminum in the Earth's crust is in the form of bauxite? 
(B) Are aluminum-bearing nonbauxite minerals plentiful? 
(C) Do the aluminous minerals found iIi bauxite contain hydrated oxides? 
(D) Are aluminous hydrated oxides found in rocks? 
(E) Do large quantities of bauxite exist?

3 
 C 
 3. The author implies that corundum would be used to produce aluminum if

(A) corundum could be found that is not contaminated by silicates 
(B) the production of alumina could be eliminated as an intermediate step in manufacturing aluminum 
(C) many large deposits of very high-quality corundum were to be discovered 
(D) new technologies were to make it possible to convert corundum to a silicate 
(E) manufacturers were to realize that the world's supply of bauxite is not unlimited

tejasvkalra · Answer

can someone explain how the answer to question one is (C)?
The passage states that 
"Alumina also occurs naturally as the mineral corundum, but corundum is not found in large deposits of high purity"
Doesn't this imply that having alumina in something is not a sufficient condition for it to be classified as an aluminum ore ?

thinkvision · Answer

All correct in 3.5 mins!

Meaning of the passage - Sources of Aluminium or Alumnia (intermediary component)

1. The author implies that a mineral must either be or readily supply which of the following in order to be classified as an aluminum ore?

(A) An aggregate
(B) Bauxite
(C) Alumina - Correct, Aluminia is an intermediary product that is essentially required to make aluminium
(D) Corundum
(E) An aluminum silicate

2. The passage supplies information for answering all of the following questions regarding aluminous minerals EXCEPT:

(A) What percentage of the aluminum in the Earth's crust is in the form of bauxite? - Correct. The passage states the percentage of "Aluminium" and not bauxite
(B) Are aluminum-bearing nonbauxite minerals plentiful?
(C) Do the aluminous minerals found iIi bauxite contain hydrated oxides?
(D) Are aluminous hydrated oxides found in rocks?
(E) Do large quantities of bauxite exist?

3. The author implies that corundum would be used to produce aluminum if

(A) corundum could be found that is not contaminated by silicates
(B) the production of alumina could be eliminated as an intermediate step in manufacturing aluminum
(C) many large deposits of very high-quality corundum were to be discovered - Correct, Corundum is less efficient/rich in Aluminia (intermediary). Hence, having an aluminia rich corundum would efficient for producing Aluminium.
(D) new technologies were to make it possible to convert corundum to a silicate
(E) manufacturers were to realize that the world's supply of bauxite is not unlimited

Iceman2020 · Answer

Here's my mind map and answers to the questions.

Mind Map: Para1: Alu and the rocks bearing Alu --> Best is Bauxite --> Reasons why it is the best --> Bauxite gives Alumina --> Alumina can also be found in corundum --> However Corundum is not widely available --> Silicates another alternative --> but silicates also have some drawbacks

C 
 1. The author implies that a mineral must either be or readily supply which of the following in order to be classified as an aluminum ore?    -Now if you read the question carefully you will see the question is asking for something that "mineral must itself be" or something that "mineral must readily supply". Now with this is mind let's apply there two conditions to our options.

(A) An aggregate  mineral must readily supply "an aggregate" - Incorrect 
(B) Bauxite  mineral must readily supply "bauxite" - Incorrect 
(C) Alumina  As stated in the passage. "alumina is an intermediate product" so this matches our above two filters "mineral is alumina" or "readily supplies alumina" 
(D) Corundum  mineral must readily supply "Corundum" - Incorrect 
(E) An aluminum silicate  mineral must readily supply "An aluminum silicate" - Incorrect

A 
 2. The passage supplies information for answering all of the following questions regarding aluminous minerals EXCEPT:

(A) What percentage of the aluminum in the Earth's crust is in the form of bauxite?  The % of aluminum in earth is given. the passage does not throw light on % found as Bauxite 
(B) Are aluminum-bearing nonbauxite minerals plentiful?  "Most of the many abundant nonbauxite aluminous" 
(C) Do the aluminous minerals found iIi bauxite contain hydrated oxides?  "in which aluminum is present as hydrated oxides" 
(D) Are aluminous hydrated oxides found in rocks?  bauxite is a rock and hydrated oxides are found in bauxite 
(E) Do large quantities of bauxite exist?  "Bauxite is the richest of all those aluminous rocks that occur in large quantities"

C 
 3. The author implies that corundum would be used to produce aluminum if

The only reason given in the passage to eliminate corundum is: "is not found in large deposits of high purity"

(A) corundum could be found that is not contaminated by silicates 
(B) the production of alumina could be eliminated as an intermediate step in manufacturing aluminum 
(C) many large deposits of very high-quality corundum were to be discovered  Precisely matches with what we discussed above 
(D) new technologies were to make it possible to convert corundum to a silicate 
(E) manufacturers were to realize that the world's supply of bauxite is not unlimited

Iceman2020 · Answer

Hi tejasvkalra 1. The author implies that a mineral must either be or readily supply which of the following in order to be classified as an aluminum ore? -Now if you read the question carefully you will see the question is asking for something that "mineral must itself be" or something that "mineral must readily supply". Now with this is mind let's apply there two conditions to our options. (A) An aggregate mineral must readily supply "an aggregate" - Incorrect (B) Bauxite mineral must readily supply "bauxite" - Incorrect (C) Alumina As stated in the passage. "alumina is an intermediate product" so this matches our above two filters "mineral is alumina" or "readily supplies alumina" (D) Corundum mineral must readily supply "Corundum" - Incorrect (E) An aluminum silicate mineral must readily supply "An aluminum silicate" - Incorrect Please hit Kudos if you liked the explanation

mayurmb · Answer

According to passage
"corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum"

And answer of Q3 says "many large deposits of very high-quality corundum were to be discovered"

So does high purity implies high quality?

Posted from my mobile device

bM22 · Answer

Hi  mayurmb ,

Yes, it can be implicitly inferred from the lines in the passage: "corundum is not found in large deposits of high purity, and therefore it is an impractical source for making aluminum", implying that high purity corundum is need for making aluminium, and that it's currently not being manufactured as high purity conundrum is not present in large deposits.

Hope This Helps.
Thanks.

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Eight percent of the Earth's crust is aluminum, and there are hundreds

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Eight percent of the Earth's crust is aluminum, and there are hundreds

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