A reaction occurs between two liquid substances in a sealed container. Based on the law of conservation of mass, what will happen to the mass of the sealed container and its contents overall?
- A. If the reaction produces a gas, the mass will decrease.
- B. If the reaction produces a solid, the mass will increase.
- C. If the reaction produces a liquid, the mass will increase as well.
- D. No matter what the reaction produces, the mass will remain the same.
Correct Answer & Rationale
Correct Answer: D
The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. Therefore, regardless of whether a gas, solid, or liquid is produced, the total mass of the sealed container and its contents will remain constant. Option A is incorrect; while gas may escape in an open system, a sealed container retains all products, so mass does not decrease. Option B is misleading; while a solid may form, it does not increase the total mass, as the mass of reactants equals that of products. Option C also misinterprets mass conservation; producing a liquid does not add to the total mass. Thus, the overall mass remains unchanged throughout the reaction.
The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. Therefore, regardless of whether a gas, solid, or liquid is produced, the total mass of the sealed container and its contents will remain constant. Option A is incorrect; while gas may escape in an open system, a sealed container retains all products, so mass does not decrease. Option B is misleading; while a solid may form, it does not increase the total mass, as the mass of reactants equals that of products. Option C also misinterprets mass conservation; producing a liquid does not add to the total mass. Thus, the overall mass remains unchanged throughout the reaction.
Other Related Questions
Which of the following is the best way to measure the volume of an irregularly shaped solid, such as a rock?
- A. Use a balance to measure the mass of the rock and divide by its density.
- B. Place the rock in a graduated cylinder containing water and measure the change in water level.
- C. Use a ruler to measure the length, width, and height of the rock and multiply them together.
- D. Use a stopwatch to measure how long it takes the rock to fall a certain distance and calculate its volume from its speed.
Correct Answer & Rationale
Correct Answer: B
Measuring the change in water level in a graduated cylinder provides an accurate method for determining the volume of an irregularly shaped solid, as it directly accounts for the object's displacement of water. Using a balance to measure mass and dividing by density (Option A) only works if the density is known, which is not practical for irregular shapes. Measuring dimensions (Option C) is ineffective since irregular shapes do not conform to simple geometric formulas. Lastly, using a stopwatch to calculate volume from falling speed (Option D) is unrelated to volume measurement and introduces unnecessary complexity.
Measuring the change in water level in a graduated cylinder provides an accurate method for determining the volume of an irregularly shaped solid, as it directly accounts for the object's displacement of water. Using a balance to measure mass and dividing by density (Option A) only works if the density is known, which is not practical for irregular shapes. Measuring dimensions (Option C) is ineffective since irregular shapes do not conform to simple geometric formulas. Lastly, using a stopwatch to calculate volume from falling speed (Option D) is unrelated to volume measurement and introduces unnecessary complexity.
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.
The pitch of a sound is related to which of the following properties of a sound wave?
- A. Speed
- B. Frequency
- C. Amplitude
- D. Energy
Correct Answer & Rationale
Correct Answer: B
The pitch of a sound is directly related to its frequency, which refers to how many sound wave cycles occur in one second. Higher frequencies produce higher pitches, while lower frequencies result in lower pitches. Option A, speed, refers to how fast sound travels through a medium but does not affect pitch. Option C, amplitude, relates to the loudness or intensity of a sound rather than its pitch. Option D, energy, is associated with the overall power of the sound wave but does not determine pitch. Thus, frequency is the key property that defines the pitch of a sound.
The pitch of a sound is directly related to its frequency, which refers to how many sound wave cycles occur in one second. Higher frequencies produce higher pitches, while lower frequencies result in lower pitches. Option A, speed, refers to how fast sound travels through a medium but does not affect pitch. Option C, amplitude, relates to the loudness or intensity of a sound rather than its pitch. Option D, energy, is associated with the overall power of the sound wave but does not determine pitch. Thus, frequency is the key property that defines the pitch of a sound.
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.