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 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.
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.
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 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.