8. Which statement describes a weakness of the investigation in the passage?
Answer: C
Several of the hypotheses rely on unproven processes or estimated values.
The investigation highlights that multiple hypotheses regarding the formation of ammonia after the Tunguska Event depend on processes that have not been conclusively proven or involve estimated values, making them less reliable.
A) None of the hypotheses are directly related to the ice core data.
This statement is incorrect as the hypotheses are indeed related to the ice core data. The ice core samples provide evidence of ammonia deposits, which the hypotheses aim to explain. Therefore, the connection between the hypotheses and the ice core data is significant.
B) The Greenland ice sheet is far away from the site of the explosion in Russia.
While it is true that the Greenland ice sheet is geographically distant from the Tunguska Event site, this distance does not inherently weaken the investigation. The study focuses on the ammonia deposits found in the ice core, which can originate from atmospheric phenomena, regardless of the distance.
C) Several of the hypotheses rely on unproven processes or estimated values.
This statement accurately identifies a weakness in the investigation. Hypotheses such as the one suggesting ammonia production through high heat or the estimation of ammonia content based on the object's mass depend on assumptions that have not been empirically validated. This reliance on unproven mechanisms undermines the strength of the conclusions drawn from the investigation.
D) A few micrograms of ammonia is insufficient evidence for a conclusion.
While the amount of ammonia detected is indeed small, it does not automatically invalidate the evidence. The investigation's aim is to explore possible explanations for the observed ammonia levels, and a low concentration can still provide meaningful insights into the event's aftermath, depending on the context of the findings.
Conclusion
The correct answer identifies a critical limitation of the investigation, as several hypotheses depend on unproven processes or estimations that may not reflect the actual events surrounding the Tunguska explosion. In contrast, the other options either misinterpret the relationship between the hypotheses and the ice core data or overlook the significance of the ammonia levels, thereby failing to address the core weaknesses in the investigation.