GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 05 Aug 2020, 11:10

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

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

Author Message
TAGS:

### Hide Tags

Board of Directors
Joined: 01 Sep 2010
Posts: 3495
Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

13 Jan 2020, 03:32
Top Contributor
Question 1
00:00

based on 128 sessions

55% (01:48) correct 45% (01:58) wrong

### HideShow timer Statistics

Question 2
00:00

based on 120 sessions

77% (01:10) correct 23% (01:24) wrong

### HideShow timer Statistics

Question 3
00:00

based on 116 sessions

77% (01:02) correct 23% (01:38) wrong

### HideShow timer Statistics

Project RC Butler 2020 - Participate and win GMAT Club Tests.
Passage # 142, Date: 10-Jun-2020
This post is a part of Project RC Butler 2020. Click here for Details

Kudos for the right answer and explanation

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.

Spoiler: :: OA
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

Spoiler: :: OA
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?

Spoiler: :: OA
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

_________________
Intern
Joined: 21 Dec 2018
Posts: 41
GMAT 1: 680 Q48 V34
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

13 Jan 2020, 08:58
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 ?
Manager
Status: Risk or die!
Joined: 26 Jul 2018
Posts: 104
Location: India
GMAT 1: 650 Q48 V31
GMAT 2: 660 Q49 V31
GMAT 3: 620 Q49 V26
WE: Consulting (Investment Banking)
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

15 Jan 2020, 02:10
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
_________________
Extraordinary results demand extraordinary work!!

I'd rather live one day as a lion than 1000 years as a sheep!!
GMAT Club team member
Status: GMAT Club Team Member
Affiliations: GMAT Club
Joined: 02 Nov 2016
Posts: 6429
GPA: 3.62
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

12 Jun 2020, 00:45
+1 Kudos to posts containing answer explanation of all questions
_________________
Manager
Joined: 03 Jan 2020
Posts: 106
Location: India
Schools: ISB'21, NUS, HEC Montreal, NTU
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

12 Jun 2020, 13:27
1
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

Spoiler: :: OA
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

Spoiler: :: OA
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"

Spoiler: :: OA
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[/box_in][/box_out][/quote]
Manager
Joined: 03 Jan 2020
Posts: 106
Location: India
Schools: ISB'21, NUS, HEC Montreal, NTU
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds  [#permalink]

### Show Tags

12 Jun 2020, 13:28
1
tejasvkalra wrote:
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 ?

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
Re: Eight percent of the Earth's crust is aluminum, and there are hundreds   [#permalink] 12 Jun 2020, 13:28