Recent photographs of the planet Venus reveal long lines that appear to be the result of massive streams of lava...
GMAT Critical Reasoning : (CR) Questions
Recent photographs of the planet Venus reveal long lines that appear to be the result of massive streams of lava from volcanic eruptions. However, the lines cannot have originated from lava flows, since some of these lines are over 1,000 miles long, and recently acquired evidence shows that the surface temperature of Venus is not high enough to allow molten lava to travel much more than 200 miles before solidifying.
For an evaluation of the argument, it would be most useful to determine whether
Passage Analysis:
| Text from Passage | Analysis |
| Recent photographs of the planet Venus reveal long lines that appear to be the result of massive streams of lava from volcanic eruptions. |
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| However, the lines cannot have originated from lava flows, since some of these lines are over 1,000 miles long, and recently acquired evidence shows that the surface temperature of Venus is not high enough to allow molten lava to travel much more than 200 miles before solidifying. |
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Argument Flow:
The argument starts with an observation (lines that look like lava flows), then immediately challenges that observation with contradictory evidence (the lines are too long given Venus's temperature constraints)
Main Conclusion:
The long lines on Venus cannot have been caused by lava flows
Logical Structure:
Uses physical impossibility reasoning - if lava can only travel 200 miles before solidifying, but some lines are over 1,000 miles long, then those lines cannot be lava flows. The temperature evidence creates a hard limit that makes the lava explanation impossible.
Prethinking:
Question type:
Evaluate - We need to find what additional information would help us judge whether the author's conclusion is correct
Precision of Claims
The argument makes specific quantitative claims: lines are over 1,000 miles long, lava can only travel 200 miles max before solidifying on Venus, and surface temperature determines this limit
Strategy
For evaluate questions, we need to think about what assumptions the argument relies on that, if tested, could either strengthen or weaken the conclusion. The author concludes the lines aren't from lava flows based on distance and temperature limits. We should look for gaps in this reasoning that need verification.
This asks about meteor impacts potentially shortening the lines from their original length. While this could theoretically affect line length, it doesn't address the core issue of whether lava could have traveled 1,000+ miles in Venus's temperature conditions. Even if some lines were shortened by impacts, we'd still need to explain how lava initially traveled such vast distances given the temperature constraints. This doesn't help us evaluate the fundamental temperature-distance relationship that the argument relies on.
This focuses on whether photographs show volcanic mountain peaks. However, the argument isn't questioning whether volcanoes exist on Venus - it's specifically challenging whether lava flows could create the observed long lines given temperature limitations. Confirming volcanic activity doesn't resolve the distance-temperature contradiction that forms the heart of the argument.
This asks about current active volcanoes that could create new lava flows. But the argument is about explaining existing long lines that have already been photographed, not about future volcanic activity. Whether volcanoes are currently active doesn't help us determine if past lava flows could have created the 1,000+ mile lines we're trying to explain.
This considers whether mountain ranges might have prevented lava flows from traveling as far as they otherwise could have. This actually works against the argument's conclusion - if anything, it suggests lava flows might have been even longer without obstructions, making it harder to explain how they stayed within the 200-mile limit. This doesn't help evaluate whether the temperature constraint explanation is valid.
This directly tests whether Venus's surface temperature was substantially closer to lava's melting point when the lines formed compared to current conditions. This is crucial because the entire argument assumes that today's temperature constraints (limiting lava travel to 200 miles) also applied when the lines were created. If Venus was significantly hotter in the past, lava could have remained molten much longer and traveled much farther, potentially explaining the 1,000+ mile lines. This information would fundamentally determine whether the argument's temperature-based reasoning is sound.