On the periodic table, elements in the same row are characterized by:
- A. an increasing number of neutrons from left to right.
- B. a decreasing number of neutrons from left to right.
- C. an increasing number of protons from left to right.
- D. a decreasing number of protons from left to right.
Correct Answer & Rationale
Correct Answer: C
Elements in the same row, or period, of the periodic table are arranged by increasing atomic number, which corresponds to the number of protons. Therefore, as you move from left to right across a row, the number of protons increases. Option A is incorrect because the number of neutrons does not consistently increase across a row; it varies based on the specific isotopes of each element. Option B is also incorrect for the same reason, as neutrons can vary independently of proton count. Option D is incorrect since it suggests a decrease in protons, which contradicts the fundamental organization of the periodic table.
Elements in the same row, or period, of the periodic table are arranged by increasing atomic number, which corresponds to the number of protons. Therefore, as you move from left to right across a row, the number of protons increases. Option A is incorrect because the number of neutrons does not consistently increase across a row; it varies based on the specific isotopes of each element. Option B is also incorrect for the same reason, as neutrons can vary independently of proton count. Option D is incorrect since it suggests a decrease in protons, which contradicts the fundamental organization of the periodic table.
Other Related Questions
Which of the following best describes a comet?
- A. A small planet orbiting the Sun between Mars and Jupiter.
- B. A chunk composed primarily of metal that enters Earth's atmosphere.
- C. A chunk composed primarily of rock, ice, and dust orbiting the Sun in an elliptical path.
- D. A dark region that appears periodically on the surface of the Sun.
Correct Answer & Rationale
Correct Answer: C
Option C accurately describes a comet as a chunk composed primarily of rock, ice, and dust that orbits the Sun in an elliptical path. This definition captures the essential components and behavior of comets. Option A incorrectly defines a comet as a small planet, which is misleading; comets are distinct from asteroids and do not have the same characteristics. Option B describes a meteoroid, which is a metallic chunk entering Earth's atmosphere, not a comet. Option D refers to sunspots, which are dark regions on the Sun's surface, unrelated to comets. Each incorrect option misrepresents the nature of comets, highlighting the unique characteristics of these celestial bodies.
Option C accurately describes a comet as a chunk composed primarily of rock, ice, and dust that orbits the Sun in an elliptical path. This definition captures the essential components and behavior of comets. Option A incorrectly defines a comet as a small planet, which is misleading; comets are distinct from asteroids and do not have the same characteristics. Option B describes a meteoroid, which is a metallic chunk entering Earth's atmosphere, not a comet. Option D refers to sunspots, which are dark regions on the Sun's surface, unrelated to comets. Each incorrect option misrepresents the nature of comets, highlighting the unique characteristics of these celestial bodies.
Which of the following is a nonrenewable fossil fuel?
- A. Coal
- B. Uranium
- C. Geothermal energy
- D. Ethanol
Correct Answer & Rationale
Correct Answer: A
Coal is a nonrenewable fossil fuel formed from ancient organic matter subjected to heat and pressure over millions of years. It is finite and cannot be replenished on a human timescale. Uranium (B) is a nonrenewable resource used in nuclear energy production but is not classified as a fossil fuel. Geothermal energy (C) harnesses heat from the Earth and is considered renewable. Ethanol (D) is a biofuel derived from plant materials, making it renewable as it can be produced continuously. Thus, coal stands out as the only nonrenewable fossil fuel in this list.
Coal is a nonrenewable fossil fuel formed from ancient organic matter subjected to heat and pressure over millions of years. It is finite and cannot be replenished on a human timescale. Uranium (B) is a nonrenewable resource used in nuclear energy production but is not classified as a fossil fuel. Geothermal energy (C) harnesses heat from the Earth and is considered renewable. Ethanol (D) is a biofuel derived from plant materials, making it renewable as it can be produced continuously. Thus, coal stands out as the only nonrenewable fossil fuel in this list.
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 is always true of a chemical change?
- A. Color, shape, or texture is altered.
- B. Mass is increased.
- C. A new substance is formed.
- D. Gas or vapor is generated.
Correct Answer & Rationale
Correct Answer: C
A chemical change always results in the formation of a new substance, which is a fundamental characteristic distinguishing it from physical changes. Option A is incorrect because while color, shape, or texture may change, these alterations do not confirm a chemical change unless a new substance is produced. Option B is misleading; mass is conserved in chemical reactions, so it does not necessarily increase. Option D, while often true (as gases can be produced), is not universally applicable; some reactions do not produce gas. Hence, the formation of a new substance is the definitive indicator of a chemical change.
A chemical change always results in the formation of a new substance, which is a fundamental characteristic distinguishing it from physical changes. Option A is incorrect because while color, shape, or texture may change, these alterations do not confirm a chemical change unless a new substance is produced. Option B is misleading; mass is conserved in chemical reactions, so it does not necessarily increase. Option D, while often true (as gases can be produced), is not universally applicable; some reactions do not produce gas. Hence, the formation of a new substance is the definitive indicator of a chemical change.