A student is conducting an experiment to determine how the temperature of water affects the rate at which sugar dissolves. The student uses four beakers with the same amount of water at different temperatures: 20C, 40C, 60C, and 80C. The student adds the same amount of sugar to each beaker and stirs for the same length of time. Which of the following is the independent variable in this experiment?
- A. The amount of sugar added to each beaker.
- B. The temperature of the water in each beaker.
- C. The time it takes for the sugar to dissolve.
- D. The amount of stirring done in each beaker.
Correct Answer & Rationale
Correct Answer: B
In this experiment, the temperature of the water in each beaker is the independent variable, as it is the factor that the student deliberately changes to observe its effect on sugar dissolution. Option A, the amount of sugar, remains constant across all beakers, making it a controlled variable rather than an independent one. Option C, the time taken for sugar to dissolve, is the dependent variable, as it is measured to assess the impact of the temperature. Option D, the amount of stirring, is also controlled to ensure consistency in the experiment. Thus, only the temperature is varied to determine its influence on the rate of dissolution.
In this experiment, the temperature of the water in each beaker is the independent variable, as it is the factor that the student deliberately changes to observe its effect on sugar dissolution. Option A, the amount of sugar, remains constant across all beakers, making it a controlled variable rather than an independent one. Option C, the time taken for sugar to dissolve, is the dependent variable, as it is measured to assess the impact of the temperature. Option D, the amount of stirring, is also controlled to ensure consistency in the experiment. Thus, only the temperature is varied to determine its influence on the rate of dissolution.
Other Related Questions
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.
The rotation of Earth around its axis is responsible for which of the following?
- A. The force of gravity
- B. The day and night cycle
- C. The temperature differences between seasons
- D. The movement of continents relative to one another
Correct Answer & Rationale
Correct Answer: B
The rotation of Earth around its axis creates the day and night cycle, as different parts of the planet face the Sun and then move into its shadow. This explains why we experience daytime and nighttime in a 24-hour period. Option A is incorrect; gravity is primarily caused by Earth's mass, not its rotation. Option C is also wrong; temperature differences between seasons are due to Earth's tilt and its orbit around the Sun, not its rotation. Lastly, option D misrepresents the concept; the movement of continents is influenced by tectonic activity, not the rotation of Earth.
The rotation of Earth around its axis creates the day and night cycle, as different parts of the planet face the Sun and then move into its shadow. This explains why we experience daytime and nighttime in a 24-hour period. Option A is incorrect; gravity is primarily caused by Earth's mass, not its rotation. Option C is also wrong; temperature differences between seasons are due to Earth's tilt and its orbit around the Sun, not its rotation. Lastly, option D misrepresents the concept; the movement of continents is influenced by tectonic activity, not the rotation of Earth.
Which of the following best describes a chemical change?
- A. The melting of ice into water.
- B. The breaking of a piece of glass.
- C. The burning of wood in a fireplace.
- D. The bending of a metal wire.
Correct Answer & Rationale
Correct Answer: C
A chemical change involves a transformation that alters the substance's chemical structure. Option A describes a physical change, where ice melts into water without changing its chemical composition. Option B also represents a physical change; breaking glass does not alter the glass's chemical identity. Option D, bending a metal wire, is another physical change, as the metal's composition remains the same despite its shape being altered. In contrast, burning wood in a fireplace (Option C) results in new substances, such as ash and gases, indicating a chemical change has occurred.
A chemical change involves a transformation that alters the substance's chemical structure. Option A describes a physical change, where ice melts into water without changing its chemical composition. Option B also represents a physical change; breaking glass does not alter the glass's chemical identity. Option D, bending a metal wire, is another physical change, as the metal's composition remains the same despite its shape being altered. In contrast, burning wood in a fireplace (Option C) results in new substances, such as ash and gases, indicating a chemical change has occurred.
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.