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# Some ores deep in the Earth are rich in iron particles

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BSchool Forum Moderator
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Some ores deep in the Earth are rich in iron particles  [#permalink]

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16 Aug 2017, 22:40
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45% (medium)

Question Stats:

65% (01:42) correct 35% (02:02) wrong based on 429 sessions

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Some ores deep in the Earth are rich in iron particles. These particles are too vulnerable to the corrosive effects of oxygen to have accumulated under the oxygenated atmosphere of today. Therefore, when the ores were deposited millions of years ago, the atmosphere must have contained less oxygen than it does today

The argument above requires which of the following assumption?

A. The iron particles were exposed to the atmosphere during the period when the ores were deposited
B. Ores were more vulnerable to the effects of corrosion in the past than are today
C. Ores were deposited at various depths in the Earth
D. The oxygen level of the atmosphere remained constant during the period when ores rich in iron particles were deposited
E. Ores near the surface of the Earth are less rich in iron particles than are ores deep in the Earth

Will reveal OA after some healthy discussion

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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 00:38
Some ores deep in the Earth are rich in iron particles. These particles are too vulnerable to the corrosive effects of oxygen to have accumulated under the oxygenated atmosphere of today. Therefore, when the ores were deposited millions of years ago, the atmosphere must have contained less oxygen than it does today

The argument above requires which of the following assumption?

A. The iron particles were exposed to the atmosphere during the period when the ores were deposited - no relevance
B. Ores were more vulnerable to the effects of corrosion in the past than are today - Correct
C. Ores were deposited at various depths in the Earth - OUT OF SCOPE
D. The oxygen level of the atmosphere remained constant during the period when ores rich in iron particles were deposited - NO effect
E. Ores near the surface of the Earth are less rich in iron particles than are ores deep in the Earth - OUT OF SCOPE
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 03:09
IMO A

if ores wern't expose to atmosphere then there would not have a corrosion effect.

Waiting for OA

Thanks
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 03:14
1

If the author had not assumed that the ore was exposed to the atmosphere before it was deposited then he would not have considered the amount of oxygen present that time.
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Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 03:30
I would go for E, because it serves as an evidence to support the argument.

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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 06:52
Took me 10 mins

Go for A.

To me, A and E are contenders. But A wins

Wait for the OA
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 09:12
pikolo2510 wrote:
Some ores deep in the Earth are rich in iron particles. These particles are too vulnerable to the corrosive effects of oxygen to have accumulated under the oxygenated atmosphere of today. Therefore, when the ores were deposited millions of years ago, the atmosphere must have contained less oxygen than it does today

The argument above requires which of the following assumption?

A. The iron particles were exposed to the atmosphere during the period when the ores were deposited
B. Ores were more vulnerable to the effects of corrosion in the past than are today
C. Ores were deposited at various depths in the Earth
D. The oxygen level of the atmosphere remained constant during the period when ores rich in iron particles were deposited
E. Ores near the surface of the Earth are less rich in iron particles than are ores deep in the Earth

Will reveal OA after some healthy discussion

Conclusion : the atmosphere must have contained less oxygen than it does today.

Premise: corrosive effect of oxygen on ores.

No effect on ores ----when exposed to atmosphere ...This proves that atmosphere contains less oxygen at the time when ores got deposited ...

A says that....
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 10:02
Option A gives us a reason to believe that atmosphere contained less oxygen than it does today.
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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17 Aug 2017, 10:08
Probably A. Because if we negate, the argument breaks.

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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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19 Aug 2017, 10:55
Some ores deep in the Earth are rich in iron particles. These particles are too vulnerable to the corrosive effects of oxygen to have accumulated under the oxygenated atmosphere of today. Therefore, when the ores were deposited millions of years ago, the atmosphere must have contained less oxygen than it does today

The argument above requires which of the following assumption?

A. The iron particles were exposed to the atmosphere during the period when the ores were deposited -Correct. The conclusion is that oxygen must have been less at the time ores were formed and the premise states that the ores are rich in iron and that they would have corroded if they came in contact with oxygen. Thus we need to join the "less oxygen" and "corrosion". This option exactly does that by stating that iron particles were exposed to oxygen. As a result we can conclude that the oxygen must have been less at that time, since if the oxygen were in large amounts then the ores would have corroded and we couldn't have said that ores are rich in iron.
B. Ores were more vulnerable to the effects of corrosion in the past than are today -This is giving us an alternative to the behaviour of ores. It is weakening the argument.
C. Ores were deposited at various depths in the Earth -We don't care about the depths of earth.
D. The oxygen level of the atmosphere remained constant during the period when ores rich in iron particles were deposited -This again doesn't have to do anything with the argument at hand.
E. Ores near the surface of the Earth are less rich in iron particles than are ores deep in the Earth -We are not comparing the different types of ores.
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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11 Feb 2018, 04:23
How can the assumption be A. E is the clear winner. Pls, help.
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Re: Some ores deep in the Earth are rich in iron particles  [#permalink]

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16 Mar 2018, 11:15
pikolo2510
Expert, I cannot find the source of this question from google search, can you help me. Thank you.
Re: Some ores deep in the Earth are rich in iron particles   [#permalink] 16 Mar 2018, 11:15
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