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
Which hypothesis is suitable for this investigation?
- A. Body temperature, breathing rate, and heart rate depend on the health of the subject.
- B. Many of the body's systems respond to exercise.
- C. Body temperature, breathing rate, and heart rate increase with exercise.
- D. Subjects at rest have better health than subjects that exercise.
Correct Answer & Rationale
Correct Answer: C
Option C effectively addresses the investigation by predicting a specific relationship: that body temperature, breathing rate, and heart rate will increase with exercise. This hypothesis is testable and directly relates to physiological responses during physical activity. Option A is too broad, as it suggests a general relationship between health and various physiological metrics without focusing on exercise. Option B, while relevant, lacks specificity regarding the measurable changes in body temperature, breathing rate, and heart rate. Option D presents a misleading comparison, as it contradicts established knowledge about the benefits of exercise for health.
Option C effectively addresses the investigation by predicting a specific relationship: that body temperature, breathing rate, and heart rate will increase with exercise. This hypothesis is testable and directly relates to physiological responses during physical activity. Option A is too broad, as it suggests a general relationship between health and various physiological metrics without focusing on exercise. Option B, while relevant, lacks specificity regarding the measurable changes in body temperature, breathing rate, and heart rate. Option D presents a misleading comparison, as it contradicts established knowledge about the benefits of exercise for health.
Which statement describes one feature of the Rutherford-Bohr atom model that the Thomson model does not share?
- A. The Rutherford-Bohr model identifies different elements by the numbers of particles present.
- B. The Rutherford-Bohr model maintains the observed neutral charge of atoms.
- C. The Rutherford-Bohr model correctly describes the types of particles in the atom.
- D. The Rutherford-Bohr model restricts the positive charge of the atom to the nucleus.
Correct Answer & Rationale
Correct Answer: D
The Rutherford-Bohr model uniquely restricts the atom's positive charge to the nucleus, a significant advancement over the Thomson model, which depicts a diffuse positive charge throughout the atom. Option A is incorrect as both models can identify elements based on particle numbers, but the Rutherford-Bohr model adds more detail about electron arrangements. Option B is misleading; both models account for atomic neutrality, but the Rutherford-Bohr model provides a clearer structure. Option C is also inaccurate; while the Rutherford-Bohr model describes particles more accurately, it does not fundamentally change the types of particles present compared to Thomson's model.
The Rutherford-Bohr model uniquely restricts the atom's positive charge to the nucleus, a significant advancement over the Thomson model, which depicts a diffuse positive charge throughout the atom. Option A is incorrect as both models can identify elements based on particle numbers, but the Rutherford-Bohr model adds more detail about electron arrangements. Option B is misleading; both models account for atomic neutrality, but the Rutherford-Bohr model provides a clearer structure. Option C is also inaccurate; while the Rutherford-Bohr model describes particles more accurately, it does not fundamentally change the types of particles present compared to Thomson's model.
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.
A substance has a mass of 10 grams. This substance has 45 joules of heat added to it, and the change in temperature is 5 degrees. What is the specific heat of the substance? J/gK
Correct Answer & Rationale
Correct Answer: 0.9
To determine the specific heat, we use the formula \( c = \frac{Q}{m \Delta T} \), where \( Q \) is the heat added (45 J), \( m \) is the mass (10 g), and \( \Delta T \) is the temperature change (5 °C). Plugging in the values: \( c = \frac{45 \, \text{J}}{10 \, \text{g} \times 5 \, \text{°C}} = 0.9 \, \text{J/g°C} \). Other options may arise from calculation errors, such as misapplying the formula or using incorrect units. For instance, if one mistakenly divides by a different temperature change or mass, it would yield incorrect specific heat values. Thus, 0.9 J/gK accurately reflects the relationship between heat, mass, and temperature change for this substance.
To determine the specific heat, we use the formula \( c = \frac{Q}{m \Delta T} \), where \( Q \) is the heat added (45 J), \( m \) is the mass (10 g), and \( \Delta T \) is the temperature change (5 °C). Plugging in the values: \( c = \frac{45 \, \text{J}}{10 \, \text{g} \times 5 \, \text{°C}} = 0.9 \, \text{J/g°C} \). Other options may arise from calculation errors, such as misapplying the formula or using incorrect units. For instance, if one mistakenly divides by a different temperature change or mass, it would yield incorrect specific heat values. Thus, 0.9 J/gK accurately reflects the relationship between heat, mass, and temperature change for this substance.