PSAT Reading Question 103: Answer and Explanation

Question: 103

Is the main conclusion presented by the author of Passage 2 consistent with the properties of the coffee ring effect, as described in Passage 1?

• A. No, since Passage 1 shows that surfactants can increase the coffee ring effect if ellipsoids are present.
• B. No, since the study in Passage 1 describes how oblong spheres diminish the coffee ring effect.
• C. Yes, since the study in Passage 2 explains that surfactants have an effect on the movement of particles.
• D. Yes, since the study in Passage 2 concludes that bacteria can be genetically modified in order to produce surfactants.

Correct Answer: C

Explanation:

C

The question asks whether the main conclusion of Passage 2 agrees with Passage 1's description of the properties of the coffee ring effect. Consider one passage at a time. Choice (A) contradicts Passage 1 because lines 52–56 say We were thinking it would be useful if you could just sprinkle in a few of these ellipsoid particles to remove the coffee ring effect…and we found that sometimes this idea works and sometimes it doesn't. Eliminate (A). Eliminate (D) because Passage 1 does not discuss bacteria. Consider Passage 2 in relationship to (B) and (C). Eliminate (B) because Passage 2 focuses on surfactants and does not discuss the shape of particles. Lines 45–51 in Passage 1 say the researchers added a surfactant and the ellipsoid particles did not get stuck at the interface and flowed freely to the edge. Lines 93–98 of Passage 2 say that soap causes a counterflow from the edge back towards the centre of the stain, and in this way, you get a more uniform distribution of particles as evaporation occurs. This supports (C), so keep it. The correct answer is (C).