#16 - Chlorofluorocarbons are the best possible solvents to

[Dave Killoran]

Complete Question Explanation

Must Be True. The correct answer choice is (E)

This is a difficult question for many students, in part because they fail to identify the absolute nature of the statement in the first sentence where the author factually states that chlorofluorocarbons (CFCs) are the best possible solvents. At that point, there can be no better solvent. And, since automakers must now phase out those very useful solvents, in order to meet the new more stringent standards they will have to come up with some other approach.

Answer choice (A): while this would make some sense in the real world, there is no indication that this will for sure happen in this question. Thus, this answer is incorrect.

Answer choice (B): while some level of redesign is not unreasonable to expect, there is no indication that the redesign will be radical or that ti will fully eliminate the need to clean these sensors. This answer simply goes way too far for what we know.

Answer choice (C): This answer doesn't address cleaning sensors or meeting the new requirements in any way, and thus it cannot be correct.

Answer choice (D): The problem with this answer is the phrase, "only marginally less effective." There is simply no way to know that whatever replaces the CFCs will be just a little bit less effective (although societal predisposition to believe in technical solutions pre-progams the reader to believe this is the likely result).

Answer choice (E): This is the correct answer choice. Since the current solvents are the "best possible" solvents, and their loss will have to be made up in some way since the rules are becoming more stringent, we can infer that something other than the solvents will need to make up the difference.

[GLMDYP]

Hi Powerscore!
I find answer (C), (B) and (E) equally right, but there's only one right answer. Can you explain this question to me?
Thanks!

[David Boyle]

Hi Powerscore!
I find answer (C), (B) and (E) equally right, but there's only one right answer. Can you explain this question to me?
Thanks!

Hello,

There is no proof for B or C, but for E: if chlorofluorocarbons ("CFC's") are the most efficient solvents anywhere, and they're being phased out, then per se, something else must "make a relatively greater contribution to meeting emission standards than at present."

David

[andriana.caban]

Hi David,

Your explanations of why (B) or (C) is wrong doesn't make sense to me!

I read the stimulus and prephrased two things: 1) Whatever they replace Chlorofluorocarbon with will be less efficient since Chlorofluorocarbon is "the best possible" solvent and 2) If the Chlorofluorocarbon is phased out and there isn't anything else to use, then cars will have to be redesigned to not include cleaners.

(B) follows logically. Here, automakers phased out the use of C solvents. So, then a redesign of the car is in order since they can't use the "best" solvent anymore; and

(D) The solvents replacing C will be less efficient. I chose this answer because it matched my prephrase although I did have issue with "only marginally less effective". Since this was a MSS question, I ignored my intuition and chose.

(E) I took (E) to be wrong because of "something other". What if this something other doesn't make a greater contribution to meeting emission standard? What if this something other is generally or equally as bad as Chlorofluorocarbon?

I'm so confused. Is (E) correct because the question stem states that the cars are continuing to meet emission standards and the solvent has contributed significantly to even meeting standards in the first place. Meaning, we need to replace the old solvent with someone new in order to meet the emission requirement (since we couldn't do so before without C) and whatever we replace C with will meet the emission requirements more or "make a greater contribution" because we know that current emission requirements are being met

[KelseyWoods]

Hi Andriana!

Careful here...it's too much of a leap to say that just because they can't use the best possible solvents anymore that necessarily means they will have to totally redesign cars to not use cleaners. What if they instead just switch to using the 2nd best solvents? Or find a non-solvent way of cleaning the sensors?

We also don't know that the solutions designed to replace CFCs will be only marginally less solvent. Maybe they'll be SIGNIFICANTLY less solvent.

Emission standards are being met, but only because we're currently using CFCs. The CFCs have contributed significantly to automakers' ability to meet those standards. So if we get rid of CFCs as cleansers, and if no other cleansers can be as effective as CFCs, then something besides cleansers is going to have to pick up the slack if we're going to keep meeting those standards.

Hope this helps!

Best,
Kelsey

[anureet]

Even though I got this question right, I want to clarify some of my doubts. Cholorfluorcarbons are the best possible solvent to clean the ignition systems. However, how do we know that the second-best solvent would not be enough to clean the ignition system? It might not be as good as the chlorofluorocarbons, but how do we know it cant get the job done. For me, best possible solvent means that it is the best one out there but that does not mean there are no other solvents that cant get the job done.

[evelineliu]

Hi Anureet,

The key here is the question is looking for the answer choice that is the "most strongly supported inference." When CFC solvent cleansers are phased out, the other existing cleansers need to step up and make a relatively greater contribution to meeting emission standards than they have before. Alternatively, a cleanser that hasn't been used before can also step up and make a greater contribution.

If there is that second-best solvent as you described in your post, it is either an existing cleanser already used or one that is not used at present.

• If it's an existing cleanser already used, it may not be used to its full potential because CFC solvent cleansers are having the greatest contribution right now. Therefore, it needs to make a greater contribution moving forward.

• If it is not already used in the cleansing process, the second-best solvent still needs to make a relatively greater contribution to meeting emission standards than it is at present (which would be 0 impact as of right now).

Best,
Eveline