#26 - Concept Reference, Must Be True

[Adam Tyson]

Stick with the info from the passage, RajPatel, and not any outside info. Here, the author told us that the lower atmosphere is the troposphere, and that CFCs released there drift upwards into the stratosphere, where they have those problematic reactions. If we were looking for a replacement for CFCs, what good would it do us to look at how it behaves in the lower atmosphere? And what is this bit about chemicals "commonly found" there? Do CFCs have something to do with chemicals commonly found somewhere? Don't we want to know whether those chemicals would drift upwards, like CFC does, and what they would do up in the stratosphere? Would they release chlorine, or something like chlorine, that would damage the ozone layer? Also, is "reacting" by itself a problem, or is it only certain types of reactions that matter?

Your goal in this question is to select an answer that asks a crucial question, one that will help us better analyze a potential replacement for CFCs. This is a lot like an Evaluate the Argument question in LR, where you have to find the answer that asks the right question.

Try a thought experiment here: imagine that we are testing a potential replacement for CFCs. Let's say we are testing XYZs to see if they will do the job. Now imagine that we conduct a test to see whether XYZs react with chemicals commonly found in the lower atmosphere. What are the possible outcomes? It's either "yes, they do react" or "no, they do not react." What impact would a Yes have on our analysis? Would that mean they are not an acceptable replacement? What if the answer is No, they do not react - would that mean they are okay as a replacement? I think in either case we would be left unsure, because we wouldn't know what might happen to the ozone as a result of any of that. Are those reactions good for it, bad for it, or neutral? Would XYZs even interact with the ozone?

Since answer B doesn't ask a particularly crucial question, and answer D asks one that is more salient, answer B is not the most useful question to ask. It's not wrong to ask it, but it's just not as important to ask as answer D is. If XYZs contain parts that are similar to chlorine, the main culprit in the destruction of the ozone, that would be very useful to know. It wouldn't tell us for sure whether they are an acceptable replacement or not, but at least we would have some valuable information that would help in making that determination.

Answer B isn't a wrong answer - it's just not the best answer, and we always want the one that is best. Don't just look at answer B in isolation, but compare it to answer D. What makes one of them more useful than the other? Don't just go for an answer that could work, or that might be okay. Go for the one that is better than the other four choices!

[fork4k]

Both D and E seemed like the least wrong answers of the bunch to me, but both seemed to underdetermine the prompt.

D wasn't really adequate since even if the chemical shared nothing in common with chlorine it could've shared things in common with some other element that was also damaging to the atmosphere (and nowhere in the passage does it say chlorine is the only constituent of CFC that's bad for the ozone layer).

E also felt inadequate since even if it didn't break down into its components it could still be bad for the atmosphere. I ended up going with E, arbitrarily.

In a situation like this where both answers seem to be not fully correct, how do you decide between them? It isn't clear to me why D is any "more" correct than E.

[Adam Tyson]

The question asks which of these would be most useful to know, fork4k. That doesn't mean that the correct answer will completely settle the question of whether a particular chemical would be an acceptable replacement. it's just the one issue, from among the five answer choices, that would be most important to know.

Answer E does nothing. So what if the replacement breaks down? That doesn't tell us anything about whether it's a good replacement or not. What if it does not break down? Is that a good thing, or a bad thing? This information is not useful without something more.

But knowing whether it has something in common with chlorine would be very important, because chlorine was the big problem for the ozone. While that doesn't completely settle the issue, it's the kind of thing we should care about, a lot. What if it's exactly like chlorine? That would be bad! What if it's nothing like chlorine? That at least gives us some hope that it won't be a problem. Does it prove it? No. But it's still something useful to know, one way or the other, and that makes it the best answer of the ones presented.