In 1908, a huge explosion known as the Tunguska Event flattened trees for miles across a remote area of Russia. Scientists now think an asteroid or a comet entered Earth's atmosphere, causing the explosion. Ice core samples from an ice sheet in Greenland reveal signs of this enormous explosion: deposits of ammonia equal to 5 micrograms per square meter. But how exactly did these telltale molecules form?
• Hypothesis 1: The Tunguska explosion started forest fires, known to produce ammonia. Data indicates that such fires would have deposited an amount of ammonia over the Northern Hemisphere equaling 0.1 micrograms per square meter.
• Hypothesis 2: Up to 1% of the object's mass might have been ammonia, and this ammonia might have spread over the Northern Hemisphere. Approximately 0.00005 micrograms of ammonia per square meter are predicted by this hypothesis.
• Hypothesis 3: Since many compounds form in the presence of high heat, the ammonia could
have been produced as the falling object heated the atmosphere. However, heat alone is not
sufficient to cause the formation of ammonia.
• Hypothesis 4: As it passed through the atmosphere, the object pushed air in front of it at high pressure. Nitrogen and hydrogen combine to form ammonia under similar pressure. Considering the amount of hydrogen expected in a comet and the available nitrogen in Earth's atmosphere, approximately 5 micrograms of ammonia per square meter would have been deposited under this hypothesis.
best explains the ammonia deposits found in ice core samples from the time of the Tunguska Event. The evidence that best supports the validity of this hypothesis is the-
- A. Hypothesis 2
- B. heat produced by fast-moving objects in the atmosphere
- C. Hypothesis 1
- D. match between measured and predicted amounts of ammonia
Correct Answer & Rationale
Correct Answer: A,D
The ammonia deposits found in ice core samples from the time of the Tunguska Event suggest a significant environmental impact. Hypothesis 2 (Option A) likely proposes a link between the event and the ammonia presence, making it relevant for explaining the deposits. Option B, which discusses heat from fast-moving objects, does not directly address ammonia production or accumulation. Hypothesis 1 (Option C) may not provide sufficient evidence or detail to support the ammonia findings. Option D highlights the alignment between measured and predicted ammonia levels, reinforcing the validity of Hypothesis 2 as it connects empirical data with theoretical expectations.
The ammonia deposits found in ice core samples from the time of the Tunguska Event suggest a significant environmental impact. Hypothesis 2 (Option A) likely proposes a link between the event and the ammonia presence, making it relevant for explaining the deposits. Option B, which discusses heat from fast-moving objects, does not directly address ammonia production or accumulation. Hypothesis 1 (Option C) may not provide sufficient evidence or detail to support the ammonia findings. Option D highlights the alignment between measured and predicted ammonia levels, reinforcing the validity of Hypothesis 2 as it connects empirical data with theoretical expectations.
Other Related Questions
Which statement describes a weakness of the investigation in the passage?
- A. None of the hypotheses are directly related to the ice core data.
- B. The Greenland ice sheet is far away from the site of the explosion in Russia.
- C. Several of the hypotheses rely on unproven processes or estimated values.
- D. A few micrograms of ammonia is insufficient evidence for a conclusion.
Correct Answer & Rationale
Correct Answer: C
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
Option C highlights a significant weakness, as relying on unproven processes or estimated values can lead to unreliable conclusions, undermining the investigation's credibility. Option A is incorrect because hypotheses can be related to data in broader contexts, even if not directly. Option B misrepresents the geographical relevance; distance alone does not invalidate the connection between the ice core data and the explosion. Option D, while suggesting a concern about evidence quantity, does not address the fundamental issue of reliance on unproven processes that can skew the investigation's outcomes.
What natural process is required to connect the ice core data to the Tunguska Event?
- A. the cycling of carbon in forest fires
- B. the interaction of comets with the solar wind
- C. the movement of glaciers due to gravity
- D. the constant mixing of the atmosphere
Correct Answer & Rationale
Correct Answer: D
Connecting ice core data to the Tunguska Event necessitates understanding atmospheric dynamics, which is achieved through the constant mixing of the atmosphere. This mixing disperses particles and gases, allowing researchers to correlate ice core samples with historical events, including the Tunguska explosion. Option A, the cycling of carbon in forest fires, is unrelated to the atmospheric conditions or the specific data derived from ice cores. Option B, the interaction of comets with the solar wind, pertains to space phenomena rather than terrestrial atmospheric processes. Option C, the movement of glaciers due to gravity, describes glacial dynamics but does not address the atmospheric mixing needed to link ice core data to the event.
Connecting ice core data to the Tunguska Event necessitates understanding atmospheric dynamics, which is achieved through the constant mixing of the atmosphere. This mixing disperses particles and gases, allowing researchers to correlate ice core samples with historical events, including the Tunguska explosion. Option A, the cycling of carbon in forest fires, is unrelated to the atmospheric conditions or the specific data derived from ice cores. Option B, the interaction of comets with the solar wind, pertains to space phenomena rather than terrestrial atmospheric processes. Option C, the movement of glaciers due to gravity, describes glacial dynamics but does not address the atmospheric mixing needed to link ice core data to the event.
Scientists can indirectly observe temperatures and insolation (the Intensity or direct solar radiation) in the distant past by measuring oxygen isotope ratios in ice cores collected from polar ice. The graph presents data for the period from what ta200.000 years ago. What time period in the graph shows the greatest correlation between Milankovitch cycles and climate?
- A. 140,000-160,000 years ago
- B. 120,000-140,000 years ago
- C. 100,000-120,000 years ago
- D. 160,000-180,000 years ago
Correct Answer & Rationale
Correct Answer: C
The time period from 100,000 to 120,000 years ago exhibits the greatest correlation between Milankovitch cycles and climate, as evidenced by significant fluctuations in temperature and insolation reflected in the oxygen isotope ratios. This interval aligns closely with the timing of glacial and interglacial periods influenced by Earth's orbital changes. Options A and B show notable climate changes, but they do not align as strongly with Milankovitch cycles, indicating less correlation. Option D, while part of the broader glacial cycle, reveals less pronounced temperature shifts, making it less relevant to the question of correlation.
The time period from 100,000 to 120,000 years ago exhibits the greatest correlation between Milankovitch cycles and climate, as evidenced by significant fluctuations in temperature and insolation reflected in the oxygen isotope ratios. This interval aligns closely with the timing of glacial and interglacial periods influenced by Earth's orbital changes. Options A and B show notable climate changes, but they do not align as strongly with Milankovitch cycles, indicating less correlation. Option D, while part of the broader glacial cycle, reveals less pronounced temperature shifts, making it less relevant to the question of correlation.
Which statement is a valid conclusion from the data?
- A. The male athletes used more energy than the female athletes after 30 minutes of exercise.
- B. Strenuous exercise is more difficult for male athletes than female athletes.
- C. The average increase in heart rate was lower for the females than for the males.
- D. All the females had a lower heart rate than the males after 30 minutes of exercise.
Correct Answer & Rationale
Correct Answer: C
Option C accurately reflects the data, indicating a measurable difference in heart rate between male and female athletes after 30 minutes of exercise. This conclusion is supported by the data trends, which typically show a higher average heart rate in males. Option A makes an assumption about energy expenditure without specific data to support it, making it invalid. Option B incorrectly suggests a subjective comparison of difficulty, which cannot be deduced from heart rate data alone. Lastly, Option D overgeneralizes by claiming that all females had lower heart rates than males, which is unlikely and not supported by typical statistical findings, as individual variations exist.
Option C accurately reflects the data, indicating a measurable difference in heart rate between male and female athletes after 30 minutes of exercise. This conclusion is supported by the data trends, which typically show a higher average heart rate in males. Option A makes an assumption about energy expenditure without specific data to support it, making it invalid. Option B incorrectly suggests a subjective comparison of difficulty, which cannot be deduced from heart rate data alone. Lastly, Option D overgeneralizes by claiming that all females had lower heart rates than males, which is unlikely and not supported by typical statistical findings, as individual variations exist.