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
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.
Of the following, which has Earth completed when it makes one revolution around the Sun?
- A. One Earth year
- B. One Earth day
- C. One light year
- D. One lunar month
Correct Answer & Rationale
Correct Answer: A
When Earth completes one revolution around the Sun, it takes approximately 365.25 days, which defines one Earth year. Option B, one Earth day, represents the time it takes for Earth to rotate on its axis, not its orbit around the Sun. Option C, one light year, is a measure of distance that light travels in one year, not a measure of time related to Earth's orbit. Option D, one lunar month, refers to the time it takes for the Moon to orbit Earth, which is about 29.5 days, and is unrelated to Earth's revolution around the Sun.
When Earth completes one revolution around the Sun, it takes approximately 365.25 days, which defines one Earth year. Option B, one Earth day, represents the time it takes for Earth to rotate on its axis, not its orbit around the Sun. Option C, one light year, is a measure of distance that light travels in one year, not a measure of time related to Earth's orbit. Option D, one lunar month, refers to the time it takes for the Moon to orbit Earth, which is about 29.5 days, and is unrelated to Earth's revolution around the Sun.
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.
Which THREE of the following are health problems associated with long-term exposure to air pollution?
- A. Accelerated aging of the lungs
- B. Increased lung capacity
- C. Increased risk of asthma
- D. Increased risk of cardiovascular disease
Correct Answer & Rationale
Correct Answer: A,C,D
Long-term exposure to air pollution can lead to several significant health issues. Option A, accelerated aging of the lungs, is accurate as pollutants can damage lung tissue over time, reducing function. Option C is also correct; exposure to air pollution is linked to a higher incidence of asthma, particularly in children, due to airway inflammation and increased sensitivity. Option D is valid as well; numerous studies show that air pollution significantly raises the risk of cardiovascular diseases due to systemic inflammation and oxidative stress. Conversely, Option B, increased lung capacity, is incorrect. Air pollution typically impairs lung function rather than enhancing it, leading to reduced capacity over time.
Long-term exposure to air pollution can lead to several significant health issues. Option A, accelerated aging of the lungs, is accurate as pollutants can damage lung tissue over time, reducing function. Option C is also correct; exposure to air pollution is linked to a higher incidence of asthma, particularly in children, due to airway inflammation and increased sensitivity. Option D is valid as well; numerous studies show that air pollution significantly raises the risk of cardiovascular diseases due to systemic inflammation and oxidative stress. Conversely, Option B, increased lung capacity, is incorrect. Air pollution typically impairs lung function rather than enhancing it, leading to reduced capacity over time.