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
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.
Sommer's research concludes that cheetahs have sufficient genetic diversity to respond to common diseases, but may still be at risk of new diseases. Which statement from the passage supports this conclusion?
- A. Major histocompatibility complex (MHC) genes are used by the body to identify self from non-self...
- B. The variation in MHC genes in cheetahs is still smaller than that for other big cat species but appears to be sufficient...
- C. If any of the genetic factors are different, then the immune system of the individual...
- D. Sommer's research determined how many alleles are present on two different types of MHC genes...
Correct Answer & Rationale
Correct Answer: B
Option B directly supports Sommer's conclusion by highlighting that the variation in MHC genes among cheetahs, while less than in other big cats, is adequate for their immune response to common diseases. This indicates sufficient genetic diversity for disease management, aligning with the research's findings. Option A discusses the function of MHC genes but does not address their variation in cheetahs, making it less relevant. Option C mentions genetic factors affecting immune response but lacks specific information about cheetah genetic diversity. Option D focuses on the number of alleles without linking it to the implications for disease response, thus failing to support the conclusion effectively.
Option B directly supports Sommer's conclusion by highlighting that the variation in MHC genes among cheetahs, while less than in other big cats, is adequate for their immune response to common diseases. This indicates sufficient genetic diversity for disease management, aligning with the research's findings. Option A discusses the function of MHC genes but does not address their variation in cheetahs, making it less relevant. Option C mentions genetic factors affecting immune response but lacks specific information about cheetah genetic diversity. Option D focuses on the number of alleles without linking it to the implications for disease response, thus failing to support the conclusion effectively.
The cladogram shows the relatedness of several organisms based on shared characteristics. Which characteristic separates catfish from frogs?
- A. Suborbital fenestra
- B. Amniotic egg
- C. Four limbs
- D. Bony skeleton
Correct Answer & Rationale
Correct Answer: B
The presence of an amniotic egg is a key characteristic that distinguishes frogs from catfish. Frogs, as amphibians, undergo a life cycle that includes an aquatic larval stage, while catfish, as fish, do not produce amniotic eggs and instead lay eggs in water. Option A, suborbital fenestra, relates to skull structure and is not a defining characteristic that separates these groups. Option C, four limbs, applies to frogs but not to catfish, which possess fins instead. Option D, bony skeleton, is present in both groups, making it an insufficient distinguishing trait.
The presence of an amniotic egg is a key characteristic that distinguishes frogs from catfish. Frogs, as amphibians, undergo a life cycle that includes an aquatic larval stage, while catfish, as fish, do not produce amniotic eggs and instead lay eggs in water. Option A, suborbital fenestra, relates to skull structure and is not a defining characteristic that separates these groups. Option C, four limbs, applies to frogs but not to catfish, which possess fins instead. Option D, bony skeleton, is present in both groups, making it an insufficient distinguishing trait.
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 between solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Thus, the equation must reflect the consumption of energy during the process. Option B correctly shows that ammonium nitrate (NH4NO3) and water react to form ammonium hydroxide (NH4OH) and nitric acid (HNO3), while requiring energy input. Option A incorrectly suggests energy is released, which contradicts the endothermic nature of the reaction. Option C implies that energy is produced, which is also incorrect. Option D similarly misrepresents the reaction by suggesting energy is released, aligning with an exothermic process rather than the observed endothermic reaction.
The reaction between solid ammonium nitrate and water is endothermic, meaning it absorbs energy. Thus, the equation must reflect the consumption of energy during the process. Option B correctly shows that ammonium nitrate (NH4NO3) and water react to form ammonium hydroxide (NH4OH) and nitric acid (HNO3), while requiring energy input. Option A incorrectly suggests energy is released, which contradicts the endothermic nature of the reaction. Option C implies that energy is produced, which is also incorrect. Option D similarly misrepresents the reaction by suggesting energy is released, aligning with an exothermic process rather than the observed endothermic reaction.