Reading Comprehension

PT146 · S4 · P4 · Q27 Chlorofluorocarbons and the Ozone

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By 1970 it was well established that ultraviolet light from the sun contributes to skin cancer.

Topic

The effects of chlorofluorocarbons (CFCs) on ozone depletion and the resulting public policy response.

Framework

Problem / Solution

Main Point

Molina and Rowland discovered that CFCs deplete the ozone layer, which protects us from cancer-causing ultraviolet radiation, prompting international policy change to control these pollutants. (Paragraph 2) This is wrapped up in Paragraph 4, where it summarizes the outcome:

P1: Importance of the Ozone Layer

By 1970, it was understood that ultraviolet radiation from the sun can cause skin cancer, but thankfully Earth's ozone layer filters out much of this harmful radiation.

P2: Discovery of the Ozone Problem

Scientists Molina and Rowland revealed that man-made chemicals called CFCs, found in products like aerosols and refrigerants, break down in the upper atmosphere and release chlorine, which destroys ozone. A single chlorine atom can wipe out thousands of ozone molecules.

P3: The Lasting Threat and Call to Action

Their research showed that even if we stopped using CFCs immediately, the chemicals already present would keep damaging ozone for many years. Molina and Rowland pushed for urgent public policies to address this environmental danger, leading to political attention and involvement in research committees.

27.

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

  1. No refrigerant chemicals other than

    Too Strong: no

    We were told that some CFCs were refrigerants. This answer is saying that "all known refrigerants are CFCs". We can't support that anywhere in the passage.

    3% picked this

  2. Correct

    Refrigerant chemicals developed as substitutes

    Why this is right

    This is supported by the final sentence, as well as more broadly by the whole point of the passage. CFCs were discovered to be terrible for the ozone layer because they broke down into chlorine atoms. A chlorine atom in the stratosphere would kill 100,000 useful oxygen atoms, thus depleting that layer of ozone. We know from the story of this passage that eventually this discovery translated into action. CFCs were banned in the late 1970s and naturally they would be replaced by something less harmful to the ozone layer (since that's the whole reason for the ban). The final sentence says that once CFCs were banned in the late 1970s, it led to more environmentally friendly refrigerant chemicals. In what sense were these new refrigerant chemicals more environmentally friendly? The passage doesn't specifically say, but since these new chemicals were designed as a response to the CFC's, which were damaging because of the chlorine atoms they released into the stratosphere, it's common sense to think the passage is saying, 'these new refrigerants were not as bad when it came to releasing chlorine atoms into the stratosphere".

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

    71% picked this

  3. CFCs were originally used in

    Too Strong: most Unsupported Causal Relationship

    We were never told why CFC's were originally used. Maybe it was because they provided the most energy-efficient means of refrigeration. Maybe they provided the 2nd most energy-efficient means but they smelled better, or they were easier to make cheaply. We have no idea.

    2% picked this

  4. The Montreal Protocol led to

    Contradicted

    The final two sentences suggest the opposite of this. The Montreal Protocol wasn't until 1987, but we're told that North America ceased CFC production in the late 1970s, when CFC's were banned.

    19% picked this

  5. Some of the refrigerant chemicals

    Out of Scope: manufactured today

    We never hear about any refrigerant chemicals made today, so we have no support to say anything about them.

    6% picked this

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