When the water on the surface of a lake is just about to freeze, the temperature of the water at the bottom of the lake will be approximately 4°C. This is due to the unique property of water where it reaches its maximum density at 4°C. As the surface water cools down to 0°C and begins to freeze, itRead more
When the water on the surface of a lake is just about to freeze, the temperature of the water at the bottom of the lake will be approximately 4°C. This is due to the unique property of water where it reaches its maximum density at 4°C. As the surface water cools down to 0°C and begins to freeze, it becomes less dense and remains on top, while the denser water at 4°C sinks to the bottom. This process ensures that the bottom of the lake remains at a relatively constant temperature of 4°C, providing a stable environment for aquatic life during winter. The layering effect, known as thermal stratification, prevents the entire lake from freezing solid, thus preserving the ecosystem within. Therefore, the correct answer is [D] 4° C.
The correct answer is [B]. A small space is left at the joint between two railway tracks to accommodate the expansion and contraction of the metal due to temperature changes. This phenomenon is known as thermal expansion. Metals, including steel used in railway tracks, expand when heated and contracRead more
The correct answer is [B]. A small space is left at the joint between two railway tracks to accommodate the expansion and contraction of the metal due to temperature changes. This phenomenon is known as thermal expansion. Metals, including steel used in railway tracks, expand when heated and contract when cooled. If no space is provided, the tracks would buckle and deform during hot weather as the metal expands. Conversely, in cold weather, the lack of space could cause the tracks to contract and create gaps that might lead to derailments. Therefore, these gaps are crucial for maintaining the structural integrity and safety of the railway system. This precautionary measure is essential for the reliable and safe operation of trains, preventing potential accidents and ensuring smooth travel. The correct answer is [B] Because the metal expands when heated and contracts when cooled.
The correct answer is option A. When water freezes, it expands as it forms ice crystals, exerting pressure on the walls of the bottle. This expansion exceeds the tensile strength of the bottle material, causing it to rupture. Option B is incorrect because the bottle doesn't shrink at freezing point;Read more
The correct answer is option A. When water freezes, it expands as it forms ice crystals, exerting pressure on the walls of the bottle. This expansion exceeds the tensile strength of the bottle material, causing it to rupture. Option B is incorrect because the bottle doesn’t shrink at freezing point; rather, it remains the same size. Option C is irrelevant to the mechanism of bottle breakage due to freezing. Option D is incorrect because water expands when it freezes, not when heated. Therefore, the expansion of water upon freezing, rather than any external factors or properties of the bottle, is the primary reason for the bottle breaking when filled with water and allowed to freeze.
The correct answer is option A. When the solid metal ball is heated, the particles within it gain kinetic energy, causing them to vibrate more vigorously. This increased vibration leads to expansion throughout the metal, including the cavity inside. As the metal expands, the volume of the cavity incRead more
The correct answer is option A. When the solid metal ball is heated, the particles within it gain kinetic energy, causing them to vibrate more vigorously. This increased vibration leads to expansion throughout the metal, including the cavity inside. As the metal expands, the volume of the cavity increases, resulting in option A: an increase in volume. This phenomenon is due to the thermal expansion properties of the metal, which causes it to expand uniformly in all directions when heated. Therefore, heating the metal ball will cause the volume of the cavity inside it to increase, as the metal expands to accommodate the higher temperature, resulting in a larger volume for the cavity.
The correct answer is; option A. When a glass rod is kept in steam, its length increases due to thermal expansion. However, the width of the glass rod remains unaffected. This phenomenon occurs because glass primarily expands in one direction when subjected to heat, which is along its length. The moRead more
The correct answer is; option A. When a glass rod is kept in steam, its length increases due to thermal expansion. However, the width of the glass rod remains unaffected. This phenomenon occurs because glass primarily expands in one direction when subjected to heat, which is along its length. The molecular structure of glass allows for expansion in the direction of the applied heat while maintaining relatively unchanged dimensions perpendicular to that direction. Therefore, although the glass rod elongates when exposed to steam, its width does not experience significant alteration. Option B is incorrect as the width doesn’t decrease. Option C is incorrect as the width doesn’t increase. Option D is irrelevant as the question pertains to physical changes rather than structural disorganization. Thus, the correct choice is option A, where the width of the glass rod remains unaffected by exposure to steam.
The correct answer is option C. In summer, the heat causes rubber to harden, reducing its flexibility. When air inside the bicycle tube heats up, it expands. However, the hardened rubber cannot expand adequately to accommodate the increased pressure. This results in heightened stress on the tube, maRead more
The correct answer is option C. In summer, the heat causes rubber to harden, reducing its flexibility. When air inside the bicycle tube heats up, it expands. However, the hardened rubber cannot expand adequately to accommodate the increased pressure. This results in heightened stress on the tube, making it more prone to bursting, specifically due to the rigidity caused by heat. Therefore, option C best explains why bicycle tubes burst mostly in summer. Options A and B are incorrect, as the tube doesn’t burst directly due to heat or because rubber becomes weak.
The correct answer is option D. When water is cooled from 10°C to 0°C, its density decreases until it reaches 4°C, where it is at its minimum. Below 4°C, water begins to expand as it approaches the freezing point, causing its density to increase again. This is due to the unique behavior of water, whRead more
The correct answer is option D. When water is cooled from 10°C to 0°C, its density decreases until it reaches 4°C, where it is at its minimum. Below 4°C, water begins to expand as it approaches the freezing point, causing its density to increase again. This is due to the unique behavior of water, where its density decreases as it cools until it reaches 4°C, after which it starts to increase due to the formation of ice crystals. Therefore, option D accurately describes the changes in density as water is cooled from 10°C to 0°C. Options A, B, and C are incorrect because they do not accurately represent the behavior of water’s density over this temperature range.
The correct answer is option A. When hot water is sprinkled on a thick glass, the sudden temperature change causes the glass to expand rapidly. Glass is a poor conductor of heat, so uneven heating can occur, leading to uneven expansion. This uneven expansion creates stress within the glass, which caRead more
The correct answer is option A. When hot water is sprinkled on a thick glass, the sudden temperature change causes the glass to expand rapidly. Glass is a poor conductor of heat, so uneven heating can occur, leading to uneven expansion. This uneven expansion creates stress within the glass, which can exceed its tensile strength, ultimately causing it to fracture. Therefore, the sudden expansion of the glass due to the hot water is the primary reason for its breakage in this scenario. Options B, C, and D are incorrect because the breakage is primarily caused by thermal expansion rather than compression, water evaporation, or chemical reaction with the glass.
The correct answer is option A. Metal tea pots have wooden handles because wood is a poor conductor of heat compared to metal. This property prevents the handle from becoming too hot to touch, allowing users to safely pour hot tea without burning their hands. Option B is incorrect because the primarRead more
The correct answer is option A. Metal tea pots have wooden handles because wood is a poor conductor of heat compared to metal. This property prevents the handle from becoming too hot to touch, allowing users to safely pour hot tea without burning their hands. Option B is incorrect because the primary reason for wooden handles is heat insulation rather than electric shock prevention. Option C is irrelevant to the functional purpose of the handle. Option D is also irrelevant as cleanliness is not directly related to the choice of material for the handle. Therefore, option A best explains why metal tea pots often have wooden handles, as they provide thermal insulation and ensure user safety during handling.
The correct answer is option C. Water is used in hot water bags because of its high specific heat capacity. This means it can absorb and retain a large amount of heat, making it effective for providing warmth when used in hot water bags. Options A, B, and D are not the primary reasons for choosing wRead more
The correct answer is option C. Water is used in hot water bags because of its high specific heat capacity. This means it can absorb and retain a large amount of heat, making it effective for providing warmth when used in hot water bags. Options A, B, and D are not the primary reasons for choosing water; rather, it’s the specific heat capacity that makes it suitable for this purpose. Water’s availability, affordability, and ease of heating may be secondary factors, but the main reason is its high specific heat, allowing it to store and release heat effectively for therapeutic use in hot water bags. Therefore, option C best explains why water is commonly used in hot water bags.
The water on the surface of a lake is just about to freeze. What will be the temperature of water at the bottom of the lake?
When the water on the surface of a lake is just about to freeze, the temperature of the water at the bottom of the lake will be approximately 4°C. This is due to the unique property of water where it reaches its maximum density at 4°C. As the surface water cools down to 0°C and begins to freeze, itRead more
When the water on the surface of a lake is just about to freeze, the temperature of the water at the bottom of the lake will be approximately 4°C. This is due to the unique property of water where it reaches its maximum density at 4°C. As the surface water cools down to 0°C and begins to freeze, it becomes less dense and remains on top, while the denser water at 4°C sinks to the bottom. This process ensures that the bottom of the lake remains at a relatively constant temperature of 4°C, providing a stable environment for aquatic life during winter. The layering effect, known as thermal stratification, prevents the entire lake from freezing solid, thus preserving the ecosystem within. Therefore, the correct answer is [D] 4° C.
See lessWhy is a small space left at the joint between two railway tracks?
The correct answer is [B]. A small space is left at the joint between two railway tracks to accommodate the expansion and contraction of the metal due to temperature changes. This phenomenon is known as thermal expansion. Metals, including steel used in railway tracks, expand when heated and contracRead more
The correct answer is [B]. A small space is left at the joint between two railway tracks to accommodate the expansion and contraction of the metal due to temperature changes. This phenomenon is known as thermal expansion. Metals, including steel used in railway tracks, expand when heated and contract when cooled. If no space is provided, the tracks would buckle and deform during hot weather as the metal expands. Conversely, in cold weather, the lack of space could cause the tracks to contract and create gaps that might lead to derailments. Therefore, these gaps are crucial for maintaining the structural integrity and safety of the railway system. This precautionary measure is essential for the reliable and safe operation of trains, preventing potential accidents and ensuring smooth travel. The correct answer is [B] Because the metal expands when heated and contracts when cooled.
See lessWhen a bottle is filled with water and allowed to freeze, then the bottle breaks, because
The correct answer is option A. When water freezes, it expands as it forms ice crystals, exerting pressure on the walls of the bottle. This expansion exceeds the tensile strength of the bottle material, causing it to rupture. Option B is incorrect because the bottle doesn't shrink at freezing point;Read more
The correct answer is option A. When water freezes, it expands as it forms ice crystals, exerting pressure on the walls of the bottle. This expansion exceeds the tensile strength of the bottle material, causing it to rupture. Option B is incorrect because the bottle doesn’t shrink at freezing point; rather, it remains the same size. Option C is irrelevant to the mechanism of bottle breakage due to freezing. Option D is incorrect because water expands when it freezes, not when heated. Therefore, the expansion of water upon freezing, rather than any external factors or properties of the bottle, is the primary reason for the bottle breaking when filled with water and allowed to freeze.
See lessA solid metal ball has a cavity inside it. When this metal ball is heated, the volume of the cavity will
The correct answer is option A. When the solid metal ball is heated, the particles within it gain kinetic energy, causing them to vibrate more vigorously. This increased vibration leads to expansion throughout the metal, including the cavity inside. As the metal expands, the volume of the cavity incRead more
The correct answer is option A. When the solid metal ball is heated, the particles within it gain kinetic energy, causing them to vibrate more vigorously. This increased vibration leads to expansion throughout the metal, including the cavity inside. As the metal expands, the volume of the cavity increases, resulting in option A: an increase in volume. This phenomenon is due to the thermal expansion properties of the metal, which causes it to expand uniformly in all directions when heated. Therefore, heating the metal ball will cause the volume of the cavity inside it to increase, as the metal expands to accommodate the higher temperature, resulting in a larger volume for the cavity.
See lessWhen a glass rod is kept in steam, its length increases but its width
The correct answer is; option A. When a glass rod is kept in steam, its length increases due to thermal expansion. However, the width of the glass rod remains unaffected. This phenomenon occurs because glass primarily expands in one direction when subjected to heat, which is along its length. The moRead more
The correct answer is; option A. When a glass rod is kept in steam, its length increases due to thermal expansion. However, the width of the glass rod remains unaffected. This phenomenon occurs because glass primarily expands in one direction when subjected to heat, which is along its length. The molecular structure of glass allows for expansion in the direction of the applied heat while maintaining relatively unchanged dimensions perpendicular to that direction. Therefore, although the glass rod elongates when exposed to steam, its width does not experience significant alteration. Option B is incorrect as the width doesn’t decrease. Option C is incorrect as the width doesn’t increase. Option D is irrelevant as the question pertains to physical changes rather than structural disorganization. Thus, the correct choice is option A, where the width of the glass rod remains unaffected by exposure to steam.
See lessWhy do bicycle tubes burst mostly in summer?
The correct answer is option C. In summer, the heat causes rubber to harden, reducing its flexibility. When air inside the bicycle tube heats up, it expands. However, the hardened rubber cannot expand adequately to accommodate the increased pressure. This results in heightened stress on the tube, maRead more
The correct answer is option C. In summer, the heat causes rubber to harden, reducing its flexibility. When air inside the bicycle tube heats up, it expands. However, the hardened rubber cannot expand adequately to accommodate the increased pressure. This results in heightened stress on the tube, making it more prone to bursting, specifically due to the rigidity caused by heat. Therefore, option C best explains why bicycle tubes burst mostly in summer. Options A and B are incorrect, as the tube doesn’t burst directly due to heat or because rubber becomes weak.
See lessIf water is cooled from 10 °C to 0 °C, then
The correct answer is option D. When water is cooled from 10°C to 0°C, its density decreases until it reaches 4°C, where it is at its minimum. Below 4°C, water begins to expand as it approaches the freezing point, causing its density to increase again. This is due to the unique behavior of water, whRead more
The correct answer is option D. When water is cooled from 10°C to 0°C, its density decreases until it reaches 4°C, where it is at its minimum. Below 4°C, water begins to expand as it approaches the freezing point, causing its density to increase again. This is due to the unique behavior of water, where its density decreases as it cools until it reaches 4°C, after which it starts to increase due to the formation of ice crystals. Therefore, option D accurately describes the changes in density as water is cooled from 10°C to 0°C. Options A, B, and C are incorrect because they do not accurately represent the behavior of water’s density over this temperature range.
See lessWhen hot water is sprinkled on a thick glass, it breaks. What is the reason for this?
The correct answer is option A. When hot water is sprinkled on a thick glass, the sudden temperature change causes the glass to expand rapidly. Glass is a poor conductor of heat, so uneven heating can occur, leading to uneven expansion. This uneven expansion creates stress within the glass, which caRead more
The correct answer is option A. When hot water is sprinkled on a thick glass, the sudden temperature change causes the glass to expand rapidly. Glass is a poor conductor of heat, so uneven heating can occur, leading to uneven expansion. This uneven expansion creates stress within the glass, which can exceed its tensile strength, ultimately causing it to fracture. Therefore, the sudden expansion of the glass due to the hot water is the primary reason for its breakage in this scenario. Options B, C, and D are incorrect because the breakage is primarily caused by thermal expansion rather than compression, water evaporation, or chemical reaction with the glass.
See lessWhy do metal tea pots have wooden handles?
The correct answer is option A. Metal tea pots have wooden handles because wood is a poor conductor of heat compared to metal. This property prevents the handle from becoming too hot to touch, allowing users to safely pour hot tea without burning their hands. Option B is incorrect because the primarRead more
The correct answer is option A. Metal tea pots have wooden handles because wood is a poor conductor of heat compared to metal. This property prevents the handle from becoming too hot to touch, allowing users to safely pour hot tea without burning their hands. Option B is incorrect because the primary reason for wooden handles is heat insulation rather than electric shock prevention. Option C is irrelevant to the functional purpose of the handle. Option D is also irrelevant as cleanliness is not directly related to the choice of material for the handle. Therefore, option A best explains why metal tea pots often have wooden handles, as they provide thermal insulation and ensure user safety during handling.
See lessWater is used in hot water bags because
The correct answer is option C. Water is used in hot water bags because of its high specific heat capacity. This means it can absorb and retain a large amount of heat, making it effective for providing warmth when used in hot water bags. Options A, B, and D are not the primary reasons for choosing wRead more
The correct answer is option C. Water is used in hot water bags because of its high specific heat capacity. This means it can absorb and retain a large amount of heat, making it effective for providing warmth when used in hot water bags. Options A, B, and D are not the primary reasons for choosing water; rather, it’s the specific heat capacity that makes it suitable for this purpose. Water’s availability, affordability, and ease of heating may be secondary factors, but the main reason is its high specific heat, allowing it to store and release heat effectively for therapeutic use in hot water bags. Therefore, option C best explains why water is commonly used in hot water bags.
See less