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.
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.
Other Related Questions
Placing solid ammonium nitrate, NH4NO3, in a container of water causes an endothermic reaction. The result is ammonium hydroxide, NH4OH, and nitric acid, HNO3. Which diagram shows the correct equation for the reaction?
- A. NH4OH + HNO3 → NH4NO3 + H2O + energy
- B. NH4NO3 + H2O + energy → NH4OH + HNO3
- C. NH4NO3 + H2O → NH4OH + HNO3 + energy
- D. NH4OH + HNO3 + energy → NH4NO3 + H2O
Correct Answer & Rationale
Correct Answer: B
The reaction involving solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Option B accurately reflects this by showing ammonium nitrate and water reacting to form ammonium hydroxide and nitric acid while requiring energy input, consistent with the endothermic nature of the process. Option A incorrectly suggests that energy is released, which contradicts the reaction's endothermic characteristic. Option C also misrepresents the energy aspect, implying that energy is produced, which is not the case. Option D similarly indicates that energy is released, misaligning with the reaction's true nature.
The reaction involving solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Option B accurately reflects this by showing ammonium nitrate and water reacting to form ammonium hydroxide and nitric acid while requiring energy input, consistent with the endothermic nature of the process. Option A incorrectly suggests that energy is released, which contradicts the reaction's endothermic characteristic. Option C also misrepresents the energy aspect, implying that energy is produced, which is not the case. Option D similarly indicates that energy is released, misaligning with the reaction's true nature.
The graph shows results from a study that sought to determine average exposure to triclosan in the U.S. population. Which statement is supported by the results in the graph?
- A. Triclosan concentration does not vary significantly among different age groups.
- B. Increased levels of triclosan in urine are related to increased age.
- C. Triclosan concentration in urine is highest in the 30- to 39-year-old age group.
- D. People aged 20-29 likely use more products containing triclosan.
Correct Answer & Rationale
Correct Answer: C
The data indicates that the highest triclosan concentration in urine occurs in the 30- to 39-year-old age group, supporting option C. This finding highlights a specific peak in exposure among this demographic. Option A is incorrect as the graph likely shows variation in triclosan levels across age groups. Option B misinterprets the data; the graph does not suggest that triclosan levels increase with age. Option D assumes usage patterns without evidence from the graph, which focuses on urinary concentration rather than product usage.
The data indicates that the highest triclosan concentration in urine occurs in the 30- to 39-year-old age group, supporting option C. This finding highlights a specific peak in exposure among this demographic. Option A is incorrect as the graph likely shows variation in triclosan levels across age groups. Option B misinterprets the data; the graph does not suggest that triclosan levels increase with age. Option D assumes usage patterns without evidence from the graph, which focuses on urinary concentration rather than product usage.
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.
A scientist studying solubility increased the temperature of a constant volume of water and measured the amount of sugar that dissolved into solution... Which of the following describes the relationship between the independent and dependent variables?
- A. As the amount of dissolved sugar increased, the temperature of the water decreased.
- B. As the water temperature increased, the amount of dissolved sugar increased.
- C. As the amount of dissolved sugar increased, the amount of water remained constant.
- D. As the water temperature increased, the amount of water decreased.
Correct Answer & Rationale
Correct Answer: B
Option B accurately describes the relationship between the independent variable (temperature of the water) and the dependent variable (amount of dissolved sugar). As temperature rises, solubility typically increases, allowing more sugar to dissolve. Option A incorrectly suggests an inverse relationship; higher temperatures do not cause the amount of dissolved sugar to decrease. Option C, while true, does not address the relationship between the two variables in question. Option D incorrectly implies that increasing temperature leads to a decrease in water volume, which is not relevant in this context.
Option B accurately describes the relationship between the independent variable (temperature of the water) and the dependent variable (amount of dissolved sugar). As temperature rises, solubility typically increases, allowing more sugar to dissolve. Option A incorrectly suggests an inverse relationship; higher temperatures do not cause the amount of dissolved sugar to decrease. Option C, while true, does not address the relationship between the two variables in question. Option D incorrectly implies that increasing temperature leads to a decrease in water volume, which is not relevant in this context.