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.
Scientists have estimated the mass of the object that caused the Tunguska Event at 5 x 10^12 kilograms (kg). If the object was a comet in which 1% of total mass was ammonia, how much ammonia did the comet contain? kg
Correct Answer & Rationale
Correct Answer: 5x10^10
To find the mass of ammonia in the comet, we calculate 1% of the total mass (5 x 10^12 kg). This is done by multiplying the total mass by 0.01: 5 x 10^12 kg × 0.01 = 5 x 10^10 kg. This calculation confirms that the comet contained 5 x 10^10 kg of ammonia. Other options may result from incorrect calculations, such as misunderstanding the percentage or misapplying the multiplication. For instance, using 0.1 instead of 0.01 would yield an answer ten times larger, while failing to convert the percentage to a decimal would also lead to an incorrect figure.
To find the mass of ammonia in the comet, we calculate 1% of the total mass (5 x 10^12 kg). This is done by multiplying the total mass by 0.01: 5 x 10^12 kg × 0.01 = 5 x 10^10 kg. This calculation confirms that the comet contained 5 x 10^10 kg of ammonia. Other options may result from incorrect calculations, such as misunderstanding the percentage or misapplying the multiplication. For instance, using 0.1 instead of 0.01 would yield an answer ten times larger, while failing to convert the percentage to a decimal would also lead to an incorrect figure.
Other Related Questions
Based on these results and assuming that whenever two materials are present their remaining energy is averaged, what would the scientist best conclude to be the composition of Saturn's rings?
- A. equal amounts of loose rocks and loose snow
- B. equal amounts of ice and bedrock
- C. a small amount of bedrock and a large amount of carbon rock
- D. large amounts of ice and smaller amounts of carbon rock
Correct Answer & Rationale
Correct Answer: D
The conclusion about Saturn's rings is supported by the composition of ice and carbon rock. Large amounts of ice are consistent with observations of Saturn’s rings, which are primarily composed of water ice particles. Smaller amounts of carbon rock align with the presence of darker materials found in the rings. Options A and B suggest equal amounts of materials that do not reflect the observed predominance of ice. Option C overestimates the presence of bedrock, which is not supported by scientific data. Thus, option D accurately captures the dominant composition of Saturn's rings.
The conclusion about Saturn's rings is supported by the composition of ice and carbon rock. Large amounts of ice are consistent with observations of Saturn’s rings, which are primarily composed of water ice particles. Smaller amounts of carbon rock align with the presence of darker materials found in the rings. Options A and B suggest equal amounts of materials that do not reflect the observed predominance of ice. Option C overestimates the presence of bedrock, which is not supported by scientific data. Thus, option D accurately captures the dominant composition of Saturn's rings.
Why is the conclusion about gene variation among cheetahs from Sommer's research more valid than the conclusion from O'Brien's research?
- A. Sommer's research was conducted more recently than O'Brien's
- B. Sommer's research used a different population of cheetahs than O'Brien's
- C. Sommer's conclusion is about disease response, while O'Brien's is about skin grafts.
- D. Sommer's conclusion is based on examining the genes, while O'Brien's conclusion is based on acceptance of a skin graft.
Correct Answer & Rationale
Correct Answer: D
Sommer's conclusion is more valid as it directly examines gene variation, providing a clearer understanding of genetic factors influencing traits. This direct analysis allows for more reliable insights into gene functionality. In contrast, O'Brien's research focuses on skin graft acceptance, which, while informative, does not provide the same depth of genetic examination. Option A is incorrect as recency does not inherently validate research findings. Option B is misleading; differing populations may affect findings but do not necessarily validate one conclusion over another. Option C misrepresents the focus of the studies; both are relevant but differ in application rather than validity.
Sommer's conclusion is more valid as it directly examines gene variation, providing a clearer understanding of genetic factors influencing traits. This direct analysis allows for more reliable insights into gene functionality. In contrast, O'Brien's research focuses on skin graft acceptance, which, while informative, does not provide the same depth of genetic examination. Option A is incorrect as recency does not inherently validate research findings. Option B is misleading; differing populations may affect findings but do not necessarily validate one conclusion over another. Option C misrepresents the focus of the studies; both are relevant but differ in application rather than validity.
Two people are standing at the edge of a high cliff. One person throws a rock horizontally off the cliff. Which uncontrolled part of this investigation can prevent the rocks from hitting the ground at the same time?
- A. gravity
- B. mass of the rocks
- C. air resistance
- D. strength of the person
Correct Answer & Rationale
Correct Answer: C
When a rock is thrown horizontally, it is influenced by both gravity and air resistance. Gravity acts equally on both rocks, ensuring they fall at the same rate. The mass of the rocks does not affect the time it takes to hit the ground in a vacuum, as all objects fall at the same rate regardless of mass. The strength of the person throwing the rock only affects the initial horizontal velocity, not the fall time. However, air resistance can vary based on the shape and size of the rocks, potentially causing differences in descent time. Thus, air resistance is the uncontrolled factor that can prevent the rocks from hitting the ground simultaneously.
When a rock is thrown horizontally, it is influenced by both gravity and air resistance. Gravity acts equally on both rocks, ensuring they fall at the same rate. The mass of the rocks does not affect the time it takes to hit the ground in a vacuum, as all objects fall at the same rate regardless of mass. The strength of the person throwing the rock only affects the initial horizontal velocity, not the fall time. However, air resistance can vary based on the shape and size of the rocks, potentially causing differences in descent time. Thus, air resistance is the uncontrolled factor that can prevent the rocks from hitting the ground simultaneously.
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.