Official Solution:

Although fullerenes - spherical molecules made entirely of carbon - were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite. Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.
Which of the following, if true, most seriously undermine the argument?


A. Confirming that the shungite genuinely contained fullerenes took careful experimentation
B. Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft
C. The mineral shungnite itself contains large amount of carbon, from which fullerenes apparently formed
D. The naturally occurring fullerenes are arranged in a previously unknown crystalline structure
E. Shungite itself is only formed under distinctive conditions


D undermines the argument by attacking the premise by suggesting that naturally occurring fullerene and synthetic fullerene differ in their structure. Since the objects of comparison are not similar, the comparison between the conditions these were formed does not stand.

A) the effort which took to confirm fullerene presence in shungite is irrelevant to the argument. What matters is whether shungite contains fullerene or not.

B) This one is close. I almost fell for it. It seems to offer an alternate explanation for the formation of fullerene. But what should be considered is, even if fullerene is formed in outer space does that change anything if it is also formed in earth? No, it does not.

C) This one provides more evidence to the argument and thus is strengthening the argument.

E) This is the premise itself.


Answer: D
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I did not choose answer D because of the words "previously unknown crystalline structure",does this mean that this structure is not known at present ?
Experts please explain ..

Thank you
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Jat

Very tricky one and good explanation.

Critical thinkers.

It has not been concluded that the one synthesized in lab is not crystalline. The basis of reasoning is that the structure was not known before - both could have crystalline structure, but different from each other.

I am not very convinced yet.

Let me talk about option D later. Let us first understand why B should be incorrect?

The argument says that Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.

Now, if it get known that this fullerenes came from some meteorite, than the argument definitely gets weakened, because now geologist will NOT be able to evaluate hypotheses about the state of the Earth's crust at the time these fullerenes were found (i.e. in meteor remains). So B IS a correct answer.

Now, looking at D: I am not a chemistry expert, but if the structure is different, wouldn't that make it a different substance/different compound altogether? Then it will not be called fullerene. e.g. coal and diamond have different structures of carbon. Because they have different structures, they have different properties. So they are different substances. With this understanding, option D seems to be invalid altogether. (My understanding about chemical structures may not be 100% correct though).

Please share your thoughts!!!

Okay got it. Nice question. Notice "Naturally occuring" modifier. Classic case of generalization. Fell for B.
It points to the fact that naturally occurring structure and the laboratory structure are two different compounds.

Thanks,
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GMAT1 650 Q48 V32.