Reading ComprehensionDifficulty: Medium

PT146 S4 P4 Q25 Explanation

Chlorofluorocarbons and the Ozone

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsInferenceScience

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Passage

By 1970 it was well established that ultraviolet light from the sun contributes to skin cancer. Fortunately, much of the sun’s most damaging ultraviolet radiation is screened out by a thin, diffuse layer of ozone—a toxic to 25 miles above the earth’s surface.

During the 1970s, however, public policy makers worldwide were alerted to the fragility of the ozone layer through the pioneering research and advocacy of two Nobel Prize-winning scientists, Mario Molina and F. Sherwood Rowland. In the absence of pollutants, stratospheric ozone concentrations should remain stable over time, with natural production and destruction chemical reaction, each chlorine atom could destroy as many as 100,000 ozone molecules before becoming inactive.

In 1974 the two scientists estimated that the atmosphere contained the accumulation of five years of global CFC production. This meant that, given the rate of diffusion and breakdown of CFCs in the atmosphere, the depletion of the ozone layer would continue for years, if not decades, even if the production and Congress and was later appointed to the U.S. National Science Foundation Committee on Fluorocarbon Technology Assessment.

Predictably, the work of Molina and Rowland and their advocacy of dramatic policy changes were subjected to attacks by critics, especially scientists with ties to the CFC industry. However, over time their views were corroborated, especially by the discovery of a hole in the ozone layer over Antarctica, and this led to in packaging for consumer spray products and the development of more environmentally friendly refrigerant chemicals.

What this question is testing

Inference

Your task

Find what must be true based on what the passage or stimulus states.

Common trap

Answers that are plausible or likely but not actually guaranteed by the text.

Winning move

Keep only the choice the statements fully support — eliminate anything that requires an extra assumption.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
25.

Which one of the following statements is most strongly supported by the information

Answer choices

  1. Too Strong: little or no12% picked this

    Little or no ozone destruction occurs naturally in the stratosphere unless

    We are being told that chlorine is terribly damaging to ozone in the stratosphere. We're never told it's the only thing that destroys ozone in the stratosphere. This is playing the age old trick of acting like "Only Thing Mentioned = Only Thing". We're actually told in the 2nd sentence of the 2nd paragraph that in its natural state, the ozone layer was "natural production and destruction in rough equilibrium". So there are other things that destroy ozone, but they are offset by natural production of more ozone.

  2. Too Strong: primarily4% picked this

    Skin cancers occur primarily because of excessive absorption of

    We are told in the first sentence that UV radiation contributes to skin cancer. We're never told it's the #1 source skin cancer. This is acting like like "the only cause of skin cancer Mentioned = the #1 cause of skin cancer".

  3. Too Strong: few6% picked this

    Few chemicals besides CFCs can result in the release of chlorine in

    We are told that CFC's can break down and result in the release of chlorine in the upper atmosphere. We're never told it's one of the only things that can result in chlorine in the upper atmosphere. Just because the passage only mentions CFC's releasing chlorine doesn't mean we get to act like CFC's are "one of only a few things" that release chlorine.

  4. Correct75% picked this

    Regulating the use of CFCs contributes indirectly to lowering the incidence

    Why this is right

    Regulating the use of CFC's contributes to keeping the ozone layer as a functional shield against incoming UV light from the sun. UV light from the sun contributes to skin cancer. So this is giving us a little causal chain: Regulate ? stronger ? less UV ? less skin CFC's ozone layer gets thru cancer When we say "A causes B, which causes C", then we can say that A directly caused B and indirectly caused C.

    Skill tested: Inference · how this choice captures the passage's function is the move to repeat next time.

  5. Too Strong: mainly3% picked this

    The upward flow of CFCs into the stratosphere occurs mainly

    We were told that the hole in the ozone layer was discovered in Antarctica, but that doesn't mean that's where the upward flow of CFC's mainly happens. The atmosphere may be thicker by the equator and thinner by the poles, which could account for why the hole first showed up near the South Pole. We are told in the 2nd paragraph, studying two freon gases - types of CFCs - they observed that, when released into the lower atmosphere, these gases slowly diffuse upward into the stratosphere. Nothing in that "diffuse upward" detail is saying anything about "mainly in Antarctica".

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