A neutral atom always contains an equal number of which of the following?
- A. Protons and electrons
- B. Protons and neutrons
- C. Neutrons and electrons
- D. Protons and alpha particles
Correct Answer & Rationale
Correct Answer: A
A neutral atom contains an equal number of protons and electrons, ensuring that the positive and negative charges balance each other out, resulting in no overall charge. Option B is incorrect because protons and neutrons do not need to be equal; the number of neutrons can vary, leading to different isotopes. Option C is also wrong, as neutrons do not have a charge and do not balance with electrons, which are negatively charged. Lastly, option D is incorrect since alpha particles, which consist of two protons and two neutrons, are not found in neutral atoms and do not play a role in charge balance.
A neutral atom contains an equal number of protons and electrons, ensuring that the positive and negative charges balance each other out, resulting in no overall charge. Option B is incorrect because protons and neutrons do not need to be equal; the number of neutrons can vary, leading to different isotopes. Option C is also wrong, as neutrons do not have a charge and do not balance with electrons, which are negatively charged. Lastly, option D is incorrect since alpha particles, which consist of two protons and two neutrons, are not found in neutral atoms and do not play a role in charge balance.
Other Related Questions
The preceding figure represents a cloud that has formed in the atmosphere above Earth's surface. Which of the following diagrams best illustrates the arrangement of charges in the cloud and on Earth's surface just before a cloud-to-ground lightning strike?
- A. Cloud: top (+), middle (-), bottom (+); Ground: (-)
- B. Cloud: top (+), middle (+), bottom (-); Ground: (+)
- C. Cloud: top (-), middle (+), bottom (+); Ground: (-)
- D. Cloud: top (+), middle (-), bottom (-); Ground: (+)
Correct Answer & Rationale
Correct Answer: D
In a thunderstorm, clouds typically develop a charge separation where the upper region becomes positively charged and the lower region negatively charged. This charge distribution is crucial for lightning formation. Option D accurately represents this arrangement: the top of the cloud is positively charged, the middle is negatively charged, and the bottom is also negatively charged, while the ground becomes positively charged in response to the cloud's negative charge. Option A incorrectly places a positive charge at the bottom of the cloud, which does not align with typical charge distributions. Option B misrepresents the charges by having two positive regions in the cloud, which is unlikely. Option C also fails by placing the top of the cloud negatively charged, contradicting the established understanding of charge distribution in storm clouds.
In a thunderstorm, clouds typically develop a charge separation where the upper region becomes positively charged and the lower region negatively charged. This charge distribution is crucial for lightning formation. Option D accurately represents this arrangement: the top of the cloud is positively charged, the middle is negatively charged, and the bottom is also negatively charged, while the ground becomes positively charged in response to the cloud's negative charge. Option A incorrectly places a positive charge at the bottom of the cloud, which does not align with typical charge distributions. Option B misrepresents the charges by having two positive regions in the cloud, which is unlikely. Option C also fails by placing the top of the cloud negatively charged, contradicting the established understanding of charge distribution in storm clouds.
Based on the food web shown, which of the following is true about the feeding relationships?
- A. Bivalves have no natural predators in the Chesapeake Bay ecosystem.
- B. Wading birds are herbivores that eat aquatic vegetation.
- C. Phytoplankton are producers that convert light energy into organic matter.
- D. Sea ducks are primary consumers that eat only bald eagles.
Correct Answer & Rationale
Correct Answer: C
In the food web, phytoplankton are classified as producers because they perform photosynthesis, converting light energy into organic matter. This foundational role supports the entire ecosystem. Option A is incorrect; bivalves often have predators, such as certain fish and birds, that feed on them. Option B misclassifies wading birds, which are carnivores that primarily feed on small fish and invertebrates, not herbivores. Option D is misleading, as sea ducks are primary consumers but do not exclusively eat bald eagles; they primarily consume aquatic plants and invertebrates. Thus, option C accurately reflects the role of phytoplankton in the ecosystem.
In the food web, phytoplankton are classified as producers because they perform photosynthesis, converting light energy into organic matter. This foundational role supports the entire ecosystem. Option A is incorrect; bivalves often have predators, such as certain fish and birds, that feed on them. Option B misclassifies wading birds, which are carnivores that primarily feed on small fish and invertebrates, not herbivores. Option D is misleading, as sea ducks are primary consumers but do not exclusively eat bald eagles; they primarily consume aquatic plants and invertebrates. Thus, option C accurately reflects the role of phytoplankton in the ecosystem.
Which of the following best describes what happens when two magnets repel each other?
- A. The objects are pulled toward one another.
- B. The objects are pushed away from one another.
- C. An electric spark jumps from one object to another.
- D. Nothing happens until the objects are touched.
Correct Answer & Rationale
Correct Answer: B
When two magnets repel each other, they exert forces that push away from one another due to their like poles (north-north or south-south). This repulsion is a fundamental property of magnetism. Option A is incorrect because it describes attraction, which occurs when opposite poles (north-south) interact. Option C is misleading; electric sparks are not a typical result of magnet repulsion. Option D is also wrong, as repulsion occurs before any physical contact, demonstrating the active interaction between the magnets. Thus, the best description of this phenomenon is that the objects are pushed away from one another.
When two magnets repel each other, they exert forces that push away from one another due to their like poles (north-north or south-south). This repulsion is a fundamental property of magnetism. Option A is incorrect because it describes attraction, which occurs when opposite poles (north-south) interact. Option C is misleading; electric sparks are not a typical result of magnet repulsion. Option D is also wrong, as repulsion occurs before any physical contact, demonstrating the active interaction between the magnets. Thus, the best description of this phenomenon is that the objects are pushed away from one another.
Which THREE of the following are considered sources of freshwater?
- A. Rivers
- B. Aquifers
- C. Oceans
- D. Glaciers
Correct Answer & Rationale
Correct Answer: A,B,D
Rivers, aquifers, and glaciers are all significant sources of freshwater. Rivers provide accessible water for ecosystems and human use, while aquifers store water underground, making it available for wells and springs. Glaciers, as large ice formations, hold substantial freshwater reserves that can feed rivers and lakes as they melt. In contrast, oceans are primarily saline and not suitable for direct human consumption or most agricultural uses. Therefore, they do not qualify as sources of freshwater, making options A, B, and D the correct choices.
Rivers, aquifers, and glaciers are all significant sources of freshwater. Rivers provide accessible water for ecosystems and human use, while aquifers store water underground, making it available for wells and springs. Glaciers, as large ice formations, hold substantial freshwater reserves that can feed rivers and lakes as they melt. In contrast, oceans are primarily saline and not suitable for direct human consumption or most agricultural uses. Therefore, they do not qualify as sources of freshwater, making options A, B, and D the correct choices.