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# The popular view is that Ozone layer’s depletion-"Tough one"

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The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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03 Feb 2013, 20:18
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Another week starts and here's the question for this week from e-GMAT:

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.

Happy Solving!

-Chiranjeev
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 00:33
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The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone. how many years is not the question, but the question is that can mankind be responsible for ozone depletion ?
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. may be less but may be even more
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies not an assumption, already mentioned in the argument
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
negate this - if the molecules from Volcanic eruptions can't reach the ozone layer, they wont deplete it
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. we don't really know whose rate is higher - volcanic eruption or industries
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 05:12
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Conclusion :- Ozone Depleting chemicals from volcano eruptions have depleted the ozone layer more than man made ozone depleting chemicals because the quantity of chemicals from volcano is more than man made chemicals

Assumption :- even if the quantity is more, the chemicals from volcano should actually cause the depletion

A. It would take mankind more than 4 billion years to destroy Ozone. - OFS, from the given premise the quantity of man made chemicals will always be lower than natural chemicals
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. - OFS the amount of ozone destroyed by a single amount is not the scope of passage
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies - already stated in the passage, and our scope is total quantity not only 1 eruption
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides. - Correct, if for some reason the chemical from volcano does not reach the ozone layer then chemical from volcano cannot be the cause of ozone depletion.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. - this option states that rate is not as important as quantity, if we negate this option then it becomes rate is as important as quantity does this break the conclusion ? no, because we do not know whose rate is higher volcano or man made, if man made chemical`s rate is higher then the conclusion breaks but if volcano`s rate is higher then the conclusion is reinforced because in this situation both the rate and quantity of volcano is higher than man made.

IMO :- D

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 07:47
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The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Paraphrase: Ozone layer depletion is real, but human is not the culprit. Why ? - Only one volcanic eruption released much more ozone-depleting chemicals than humans have ever produced. And since mankind can't even match one of them, mankind cannot be the culprit
.

Author trying to accuse the nature and exonerate humans.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone. - Doesn't help authors purpose, we are not bothered how many years does it take. we are looking at who is responsible

B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
- The author have stated already that the amount is cumulatively too large. So breaking to molecualr level is not required.

C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
- Again a stated fact in the premise. Not an assumption.

D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
- Correct. If this becomes true, then the author claim doesn't hold valid. The conclusion is: human shoots only once, but since nature explodes a bomb - nature is the culprit. This option eliminates the possibility that the bomb misses the target.

E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.
- The author says nature is responsible. And the nature wins both in rate and quantity. So it is not relevant to compare whether rate is important or quanity.
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Re: An assumption question - a tough nut to crack [#permalink]

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03 Feb 2013, 20:51
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Even though this post was reserved for posting official solution and explanation, given the quality of discussions on this forum, I think it would only help the students if they go through the thread and understand different doubts and discussion points.

Therefore, the official solution and explanations have been posted at the end of this thread.

-Chiranjeev Singh
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Last edited by egmat on 12 Feb 2013, 22:55, edited 1 time in total.

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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03 Feb 2013, 23:48
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Expert's post
egmat wrote:
Another week starts and here's the question for this week from e-GMAT:

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.

Happy Solving!

-Chiranjeev

Premise: A volcanic eruption spews forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. There has been so many of such eruptions.
Conclusion: Humans cannot be held responsible for destroying ozone.

We can see that the author's argument is based on the quantity of chemicals released. So the assumption would be based on that. Among the choices, E best fits as the assumption as it says that it is only the quantity of chemicals released that is important. Factors such as rate of release is less important.

Choice B is close but we do not know how many molecules are there in each case. If there are significantly more molecules of flourocarbons released then man caused destruction could also be significant.
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 00:34
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very good question egmat. +1 to you.
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 01:17
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The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone. how many years is not the question, but the question is that can mankind be responsible for ozone depletion ?
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. may be less but may be even more
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies not an assumption, already mentioned in the argument
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
negate this - if the molecules from Volcanic eruptions can't reach the ozone layer, they wont deplete it
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. we don't really know whose rate is higher - volcanic eruption or industries

The logic of Choice D that chemicals released in a volcanic eruption may not reach the stratosphere and therefore not destroy ozone is fine but the problem is it is not related to the author's argument. You would want to select a choice that relates to the author's argument and Choice E does that best. This is because the author makes his point by saying that the quantity of chemicals released in a volcanic eruption is enormously more than that released in man-made reactions. So his central assumption is that quantity of chemicals released determines how much of ozone is destroyed. Choice E represents that assumption by saying factors other than quantity released such as the rate of release of chemicals are not important.
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 09:49
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Well IMO D is the right answer , but in hindsight i fear that it is tempting.
I ll present my logic on selecting D.
Conclusion: Man made chemicals cannot be held responsible for ozone depletion.
Premise : Volcanic eruption has ozone depleting substance and its presence after eruption is much larger in quantity than the man made chemicals.

Prethinking Assumption: Its analogy that substantiates the conclusion. Hence Assumption should be more driven to establish the soundness of analogy.
Therefore, Something that justifies that both man made chemicals and volcanic eruption both are equal in their properties, when it comes to the destruction of the ozone layer.
or Something that establishes a similarity between man made chemicals and volcanic eruption chemicals.....

I do not think E is the right answer as it discusses about the rate is discussed , which is not more important.
I think If D is negated than conclusion cannot stand also it presents a dissimilarity between the two.

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 11:13
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Dear Dinesh2Apr,

An assumption is something which makes the conclusion valid given the premise. Now let us state the premise, assumption and conclusion

Premise: the quantity of ozone depleting chemicals released determines how much of ozone is destroyed

Assumption: the rate of release of ozone depleting chemicals may or may not be more in a volcanic eruption and is more important than the quantity of chemicals released

Now does the conclusion that the chemicals released in a volcanic eruption destroys ozone more, follow from the above? It does not. It is not necessary that the argument totally break down. It is enough if the argument does not logically follow from the premise and the assumption. That is if you do not make the assumption the conclusion will not logically follow.That itself implies that the argument has broken down.

The problem with D is that it is not in any way related to the author's argument. The author never talks of molecular structure of the chemicals. An assumption is something that links the premise and the conclusion. So for the premise that quantity released determines how much of ozone is destroyed, the logical assumption is that there are no other factors that are more important than the quantity released. So we see choice D is totally out of place given the premise. In my opinion you cannot assume more than is warranted by the argument.
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 01:26
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As per my understanding:

The argument says that if mankind cannot produce enough depleting chemicals to match those produced by the volcanic eruption (already in place) in 4 billion years. How can it be held responsible for depleting the ozone layer.

An assumption must hold true for the conclusion to be valid.

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.

Irrelevant. Even if it took mankind more than 4 billion years to destroy ozone, the volcanic eruptions would be blamed first for the eruption.

B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.

Out of scope as the question is between the source of depletion and not how much depletion is caused.

C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies

D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.

If this point is negated the argument fails as the comparison between chemicals released during volcanic eruptions and industrial chemicals would be void.

E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.

Out of scope

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 08:45
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The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. (Background information While that may be the case, the attribution of such depletion to man-made chemicals is not true.Conclusion Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history.Support. Quantity of ozone depleting Chemicals higher in one volcanic reaction than all other man-made ozone depleters combined Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.Further Support for the claim that man-made chemicals being ozone depleters isn't true.

A required assumption, is an assumption that must be true. It doesn't draw the conclusion, it merely must be factually correct. If not true, it will put doubt into the argument.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.Time. Doesn't matter.
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.Doesn't need to be true. The main comparison is total ozone depleting chemicals. Hypothetically, human depleting could be more per molecule, but the argument indicates that a volcanic eruption spews far more quantity-wise.
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companiesThis is specifically indicated in the argument
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.If it did prevent, then there'd be no way for the volcanic eruptions to deplete the ozone, so you couldn't say that the human chemicals aren't contributing to depletion.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.Even if it is more important, we don't know what about the rate? What will the rate do!? We don't know. Will a faster rate lead to more destruction? Will a slower rate lead to more destruction? If the answer said a slower rate of chemicals released doesn't lead to more destruction, then that'd be a correction assumption in my opinion

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 12:34
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SravnaTestPrep wrote:
Consider this:

Premise: Socrates is a human
Conclusion: Socrates is intelligent

What is the assumption here for you to reach the conclusion that Socrates is intelligent? The assumption should be Humans are intelligent. So the assumption is based on the premise and the conclusion. It links the two. Any extraneous information should not be considered as assumption because we figure out the assumption based on the argument. For example you cannot say that "Humans who are not beautiful are intelligent and Socrates is not beautiful" is an assumption, though the conclusion would logically follow. This is because the argument doesn't warrant that information.

That is the reason choice D does not fit as an assumption for this question.

Dear Sravna,

I have to respectfully disagree with you regarding this question. Your example is based on a sufficient assumption, whereas the question is in relation to a necessary assumption.

I certainly agree with your logic regarding the socrates example. However, that is sufficient as opposed to necessary. Whereas a necessary assumption if we drew in the sufficient assumption that you indicated

Socrates is human.
Socrates is intelligent.
Sufficient asssumption which would make argument stick: "All humans are intelligent" or "All people (people inferred to be human) named Socrates are intelligent"

However, a necessary assumption would be "All Intelligent humans are not named Bob"
This is necessary because if all intelligent humans were named Bob, then the conclusion that Socrates is intelligent couldn't follow.

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 18:44
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Expert's post
Hi All,

It has been a great discussion so far. I really enjoyed reading it - points, counter-points - I think this is what we are here for - to learn from each other.

Thank you to all and Kudos to people who put in detailed explanations for their answer choices.

Very nice and precise explanations by Anshunadir, ConnectTheDots and VariableChange.

And if some people are still wondering about OA:

We'll put up official explanations by tomorrow. In any case, explanations by Anshunadir, ConnectTheDots and VariableChange are already there.

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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 19:04
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Dinesh2Apr wrote:
Conclusion :- Ozone Depleting chemicals from volcano eruptions have depleted the ozone layer more than man made ozone depleting chemicals because the quantity of chemicals from volcano is more than man made chemicals

Assumption :- even if the quantity is more, the chemicals from volcano should actually cause the depletion

A. It would take mankind more than 4 billion years to destroy Ozone. - OFS, from the given premise the quantity of man made chemicals will always be lower than natural chemicals
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. - OFS the amount of ozone destroyed by a single amount is not the scope of passage
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies - already stated in the passage, and our scope is total quantity not only 1 eruption
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides. - Correct, if for some reason the chemical from volcano does not reach the ozone layer then chemical from volcano cannot be the cause of ozone depletion.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. - this option states that rate is not as important as quantity, if we negate this option then it becomes rate is as important as quantity does this break the conclusion ? no, because we do not know whose rate is higher volcano or man made, if man made chemical`s rate is higher then the conclusion breaks but if volcano`s rate is higher then the conclusion is reinforced because in this situation both the rate and quantity of volcano is higher than man made.

IMO :- D

Hi Dinesh,

Dinesh2Apr wrote:
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. - OFS the amount of ozone destroyed by a single amount is not the scope of passage

If amount destroyed by single molecule is out of scope, how come molecular structure discussed in Choice D is within the scope?

Dinesh2Apr wrote:
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. - this option states that rate is not as important as quantity, if we negate this option then it becomes rate is as important as quantity does this break the conclusion ? no, because we do not know whose rate is higher volcano or man made, if man made chemical`s rate is higher then the conclusion breaks but if volcano`s rate is higher then the conclusion is reinforced because in this situation both the rate and quantity of volcano is higher than man made.

The option states that rate is "not more important" than quantity - not "not as important" as quantity. So, if we negate this, we get that either rate is more important than quantity. Then, you correctly say that we don't know whose rate is higher.

But an important point here is that even if rate of man-made chemical is higher than that of volcanic eruption, the conclusion won't break apart. Why? Simply because we don't know a direct relation between rate of eruption to the depletion. If you think that that is obvious, then revisit Option D.

Negation of Option D breaks down the link between quantity of chemicals produced to their impact on the ozone layer. While chemicals released in volcanic eruption might be higher, if Option D is not true, these chemicals impact the ozone layer.

Even though you chose the right choice, the idea is that you understand these nuances so that when you see other OG question, you are more sure while selecting and rejecting option statements.

Hope this helps

Thanks,
Chiranjeev
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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05 Feb 2013, 20:21
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SravnaTestPrep wrote:
Premise 1: Quantity of chemicals released determines how much of ozone is depleted

There is the problem.

"Quantity of chemicals released determines how much of ozone is depleted." is not a premise. It is what the author is implying/assuming. It is not given as a fact.

Let's review the argument:

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. - A fact about what people generally think.

While that may be the case, the attribution of such depletion to man-made chemicals is not true. - Conclusion of the argument

Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all mankind in history. - Fact about who produces more ozone-depleting chemicals

The argument does not tell us that "Quantity of chemicals released determines how much of ozone is depleted." It is something the author is implying. He is assuming that if more chemicals are released, more ozone is depleted. The point is that if the 'chemicals released' are unable to reach the ozone layer, they cannot deplete it. So the author is assuming that the chemicals released are able to reach the ozone layer.

Hence answer has to be (D).
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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12 Feb 2013, 22:50
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Here's the official answer and explanation:

Understanding the passage

Conclusion:
The attribution of depletion of Ozone layer to man-made chemicals is not true.

Premises:
1. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history
2. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them

In this case, premises 1 and 2 are set of dependent information pieces and comprise a single reason used by the author to arrive at the conclusion. In essence, the reason is:

Ozone depleting chemicals produced by Mount Pinatubo is much greater (probably billion of times) than ozone depleting chemicals (fluorocarbons) produced by mankind.
This reason is used to signal that man-made chemicals can only play an insignificant role in the depletion of Ozone layer.
Therefore, (Conclusion) Man-made chemicals can’t be held responsible for ozone layer depletion.

Prethinking

As we can see, the argument is talking only in terms of the amount of ODC ( Ozone Depleting Chemicals), not in terms of their impact on the ozone layer. This is a missing link that is needed to establish the correctness of the argument.
So, a statement like “ODCs generated by volcanic eruptions have the same effect on the Ozone as ODCs generated by mankind”, would complete the argument.
However, this is not a must-be-true statement. Why? Because we know that the quantity of volcanic ODCs is probably billions of times greater than man-made ODCs, therefore, even if volcanic ODCs have much less effect than man-made ODCs, our conclusion would still hold.

Therefore, our only requirement can be that volcanic ODCs have at least some effect on the Ozone layer.
However, why would ODCs be called so if they don’t have any effect on Ozone layer. So, they have to have some impact. This leads me to think that there are only two situations in which the argument won't hold:

1. Volcanic ODCs don’t reach Ozone layer due to some reason (hypothetical) –
a. Probably because due to their high temperature. they react with some chemical as soon as they reach atmosphere and this reaction snaps their ability to deplete Ozone layer
b. Their chemical or physical properties is different from man-made ODCs and these properties prevent them from reaching Ozone layer

2. Volcanic ODCs can’t deplete unless the depletion has been started by man-made ODCs. Suppose, Ozone layer exists in a very stable state – this state cannot be affected by volcanic ODCs. However, once man-made ODCs can start reactions with this stable state of Ozone and deplete it, this makes the Ozone layer reactive even to Volcanic ODCs.

In both the situations above, our conclusion won’t hold. Therefore, negation of either of the two statements could be a valid assumption and therefore, answer to our question.

A. It would take mankind more than 4 billion years to destroy Ozone. – So what? We are concerned with the cause of depletion, not the time-frame. Incorrect.

B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons. – As we analyzed in the pre-thinking, this is not required. Even if a molecule of volcanic chemical destroys much less ozone than a man-made chemical, the conclusion will still hold. Therefore, this is not a must be true statement. Thus, Incorrect.

C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies – This can be inferred from the passage. Therefore, this presents no new information and thus, cannot be an assumption. Incorrect.

D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides. – This is in line with our prethinking. If these volcanic ODCs don’t reach ozone layer, then the reasoning of the argument breaks down. Therefore, this is a must-be-true statement for the argument to hold. Correct.

E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. – Given this statement is in a negative form “not more”. Let’s negate it and see if the conclusion breaks down. We can see that even if rate is more important than the quantity, it doesn’t impact the conclusion, since we don’t know whether slow rate depletes Ozone layer more or fast rate depletes more. Therefore, Incorrect.

Therefore, the answer choice is Option D.

Hope this helps

-Chiranjeev Singh
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 01:26
egmat wrote:
Another week starts and here's the question for this week from e-GMAT:

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.

Happy Solving!

-Chiranjeev

Hi all,

Frankly, i'd say that C is the assumption that we're looking for : If you negate it, you will have : The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much lower than the quantity of fluorocarbons produced by the companies. In other words and based on the argument, and if it is true, man-made chemicals like fluorocarbons are responsible for destroying ozone and therefore the argument will not be valid at all
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 02:54
Rock750 wrote:
egmat wrote:
Another week starts and here's the question for this week from e-GMAT:

The popular view is that Ozone layer’s depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

A. It would take mankind more than 4 billion years to destroy Ozone.
B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.

Happy Solving!

-Chiranjeev

Hi all,

Frankly, i'd say that C is the assumption that we're looking for : If you negate it, you will have : The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much lower than the quantity of fluorocarbons produced by the companies. In other words and based on the argument, and if it is true, man-made chemicals like fluorocarbons are responsible for destroying ozone and therefore the argument will not be valid at all

C we already know these information. at least C is an inference question

E must be the answer though D is tempting
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Re: The popular view is that Ozone layer’s depletion-"Tough one" [#permalink]

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04 Feb 2013, 07:00
Dinesh2Apr wrote:
E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released. - this option states that rate is not as important as quantity, if we negate this option then it becomes rate is as important as quantity does this break the conclusion ? no, because we do not know whose rate is higher volcano or man made, if man made chemical`s rate is higher then the conclusion breaks but if volcano`s rate is higher then the conclusion is reinforced because in this situation both the rate and quantity of volcano is higher than man made.

Dear Dinesh2Apr,

It does not matter whether the rate of chemicals released in a volcanic eruption is greater or not. The point is that there is another factor than quantity of chemicals released that may determine how much of ozone is destroyed. Think of it this way. Instead of calling it as rate of release call it as another factor. So the choice would say that there are no other factors than quantity that determines how much of ozone is destroyed. Thus we can see that the author's conclusion would hold absolutely only when quantity is the only factor that determines how much of ozone is destroyed. If there are other factors his argument is not air tight. That is the conclusion would not logically follow from the premise.
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Re: The popular view is that Ozone layer’s depletion-"Tough one"   [#permalink] 04 Feb 2013, 07:00

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