LSAT 15 - Section 2 - Question 12

Here we have a MBT question, which we should recognize from the question stem: If the statements above are true, which one of the following must on the basis of them be true*?*

This question appears to be a lot more difficult than it really is; its difficulty lies in how dense with terminology the stimulus is. If we keep our cool, and focus on discerning the logical relations behind all this scientific jargon, we should have an easy time once we actually get to the answer choices. So don’t get lost in the noise, and make sure to anchor yourself in the conditionals and conjunctions as they show up.

Our first sentence tells us that these things called pyrrole molecules can combine to form polypyrroles. I don’t know about you, but I have never in my life heard of pyrrole molecules. Don’t let yourself be thrown off by this foreign language, what you should take away from this first sentence is that there are these things, pyrroles, and they can combine together. The next sentence continues with the weird language, bringing in this new thing, zeolites. As soon as we notice that the sentence begins with an if, we should look for a conditional relationship. The sentence gives us some information about polypyrrole combination when it is exposed to zeolite, and tells us there are two possible outcomes, conjoined by an OR that should jump at us. If we diagram this conditional, we should end up with something along the lines of: PP combination + Z → chains in Z or lumps on Z. So when we have these polypyrroles form near zeolite, they do so either in lumps on the zeolite, or chains within it. Interesting! The next sentence begins with the conditional indicator when, and we should once again use the logic to guide us through the language. It’s important to note in this conditional that the polypyrrole formation is the necessary condition, what triggers the rule. It’s not the case that polypyrrole formation is enough for the zeolite to change color, it is in fact required that if zeolite changes color from yellow to black, pyrrole formed either lumps on the zeolite or chains in it.

After all this explanation of polypyrrole formation and how it works around zeolites, we are given a phenomena; some yellow zeolite was submerged in pyrrole and turned black, without any pyrrole lumps forming. If we are pre-phrasing, we should recognize that we’ve been told pyrrole formation is required for zeolite to change from yellow to black, so it must have happened either in chains in the zeolite or in lumps on its surface. Since we are told there were no lumps, it must be true that the pyrrole formed chains in the zeolite. With this in mind, let’s look at the answer choices. As always on a MBT question, we should eliminate answers by considering whether it is possible for them to not be true given the information in the stimulus.

Answer Choice (A) This answer choice must be false, as we are explicitly told the zeolite was free of pyrroles before being submerged. If you selected this, you should work on reading the stimulus more carefully.

Answer Choice (B) B also must be false as we are told that no lumps formed on the zeolites surface after it had been submerged. Once again, you should be able to eliminate this answer quickly if you carefully read the stimulus.

Correct Answer Choice (C) This answer says exactly what we inferred in our pre-phrasing. Given the information in the stimulus, it is the only possible explanation for how the zeolite changed from yellow to black. Therefore, it must be true.

Answer Choice (D) Another answer choice that must be false. The third conditional the stimulus gives us requires that polypyrroles form if a zeolite changes from yellow to black. Since the zeolite was free of pyrrole before it was submerged, and changed from yellow to black after being submerged, there must have been some polypyrrole formation when it was submerged.

Answer Choice (E) This is the only incorrect answer choice that is not necessarily false. However, it is still not the case that it must be true. We are given no support to infer with certainty what quantity of the pyrrole entered the zeolites inner chamber.