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# If carbon dioxide gas is generated in large enough quantities

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Intern
Joined: 14 Sep 2017
Posts: 34
Location: Italy
If carbon dioxide gas is generated in large enough quantities  [#permalink]

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02 Nov 2017, 01:46
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25% (medium)

Question Stats:

77% (01:51) correct 23% (02:19) wrong based on 144 sessions

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If carbon dioxide gas is generated in large enough quantities, it will collect in the atmosphere and cause an unwelcome warming effect.

The decay of plants, including trees, generates carbon dioxide, but in forests such carbon dioxide is balanced by the carbon dioxide taken in by living plants, which give off oxgen.

The use in industry of fuels derived from plants generates a large amount of carbon dioxide; such fuels include wood, coal, and oil.

If the statements above are true, which of the following can properly be concluded from them?

(A) All of the carbon dioxide that can be generated in an industrial society is attributable to plants, directly or indirectly.

(B) An unwelcome warming effect on climate cannot be avoided, since carbon dioxide is given off by the natural processes of decay in plants.

(C) Forests contribute as much carbon dioxide to the atmosphere as does the industrial use of fuel derived from plants.

(D) A society that uses plant-based fuels in industry will contribute a net surplus of carbon dioxide to the atmosphere, unless the gas is reabsorbed in some way.

(E) No matter which fuels are used by industry, there is bound to be an increase in the total amount of carbon dioxide in the atmosphere and a consequent unwelcome warming effect on climate.
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4493
Re: If carbon dioxide gas is generated in large enough quantities  [#permalink]

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03 Nov 2017, 17:30
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Fedemaravilla wrote:
If carbon dioxide gas is generated in large enough quantities, it will collect in the atmosphere and cause an unwelcome warming effect.

The decay of plants, including trees, generates carbon dioxide, but in forests such carbon dioxide is balanced by the carbon dioxide taken in by living plants, which give off oxygen.

The use in industry of fuels derived from plants generates a large amount of carbon dioxide; such fuels include wood, coal, and oil.

If the statements above are true, which of the following can properly be concluded from them?

(A) All of the carbon dioxide that can be generated in an industrial society is attributable to plants, directly or indirectly.

(B) An unwelcome warming effect on climate cannot be avoided, since carbon dioxide is given off by the natural processes of decay in plants.

(C) Forests contribute as much carbon dioxide to the atmosphere as does the industrial use of fuel derived from plants.

(D) A society that uses plant-based fuels in industry will contribute a net surplus of carbon dioxide to the atmosphere, unless the gas is reabsorbed in some way.

(E) No matter which fuels are used by industry, there is bound to be an increase in the total amount of carbon dioxide in the atmosphere and a consequent unwelcome warming effect on climate.

Dear Fedemaravilla,

I'm happy to respond.

This question has an interesting design: it doesn't follow the ordinary patterns for the GMAT CR, but the logic of it is sound.

We want to draw a conclusion. See the blog article:
GMAT Critical Reasoning: Find the Conclusion or Inference
We don't want something that could be true or is probably true. We need something that absolutely must be true.

(A) All of the carbon dioxide that can be generated in an industrial society is attributable to plants, directly or indirectly.
The prompt states: "The use in industry of fuels derived from plants generates a large amount of carbon dioxide." That's true, according to the prompt. What we don't know is whether there is another source of fuel, from something else, that produces a small amount of CO2. For example, maybe a factoring that runs purely on geothermal energy generates a small amount of CO2. That would be consistent with the prompt, but would contradict (A), so (A) might not be true. This is not a valid conclusion.

(B) An unwelcome warming effect on climate cannot be avoided, since carbon dioxide is given off by the natural processes of decay in plants.
No. The prompt explicitly tells us that "The decay of plants, including trees, generates carbon dioxide, but in forests such carbon dioxide is balanced by the carbon dioxide taken in by living plants, which give off oxygen." The forest takes care of itself, so before the Industrial Revolution, before there were any factories, the "unwelcome warming effect" was not an issue. Yes, it's an issue in our coal-drunk and oil-drunk modern world, but in an ideal future in which all power were generated by, say, solar & wind power, forms of power that emit no CO2, then the only CO2 would be from the forest, which can take care of itself. in that ideal future, the "unwelcome warming effect" would not be an issue. Therefore, it could be avoided. This is not a valid conclusion.

(C) Forests contribute as much carbon dioxide to the atmosphere as does the industrial use of fuel derived from plants.
This directly contradicts the statements given. Forest create a little, and can reabsorb that little. Factories create tons and tons, and don't reabsorb one iota of it. This directly contradicts the prompt and is not a valid conclusion.

(D) A society that uses plant-based fuels in industry will contribute a net surplus of carbon dioxide to the atmosphere, unless the gas is reabsorbed in some way.
We know that "The use in industry of fuels derived from plants generates a large amount of carbon dioxide.." The contribute a lot of CO2 to the atmosphere and reabsorb none. Now, forests & plants may reabsorb some, but whatever they can't reabsorb will be a net contribution to the atmosphere. This has to be true.

(E) No matter which fuels are used by industry, there is bound to be an increase in the total amount of carbon dioxide in the atmosphere and a consequent unwelcome warming effect on climate
No. We know that all the plant-based fuels create massive amounts of CO2, but we are not told about other types of fuel. Nuclear energy, wind power, and solar energy all produce zero CO2, and in an ideal world, all the energy in the world would be generated from those forms, which would not produce any CO2. Thus, it is possible to avoid that scenario. This is not a valid conclusion.

The only possible answer is (D).

Does all this make sense?
Mike
_________________

Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

Re: If carbon dioxide gas is generated in large enough quantities &nbs [#permalink] 03 Nov 2017, 17:30
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