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All questions of Heat for Year 3 Exam
What is the freezing point of water?- a) 0°C
- b) 100°C
- c) 32°F
- d) Both A and B
Correct answer is option 'D'. Can you explain this answer?
What is the freezing point of water?
a)
0°C
b)
100°C
c)
32°F
d)
Both A and B
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Nclex Coaching Centre answered |
The freezing point of water is 0°C or 32°F. At this temperature, water transitions from a liquid to a solid state (ice) as it releases heat energy.
What occurs during condensation?- a) A gas turns into a solid.
- b) A gas turns into a liquid.
- c) A liquid turns into a gas.
- d) A solid turns into a liquid.
Correct answer is option 'B'. Can you explain this answer?
What occurs during condensation?
a)
A gas turns into a solid.
b)
A gas turns into a liquid.
c)
A liquid turns into a gas.
d)
A solid turns into a liquid.
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Nclex Coaching Centre answered |
Condensation is the process where a gas turns into a liquid when it loses heat. For example, water vapor condenses into liquid water on a cold surface, forming droplets.
What does the term "combustion" refer to in the context of heat energy?- a) The process of freezing a substance.
- b) The chemical reaction that produces heat and light.
- c) The process of a liquid turning into a gas.
- d) The physical change of matter.
Correct answer is option 'B'. Can you explain this answer?
What does the term "combustion" refer to in the context of heat energy?
a)
The process of freezing a substance.
b)
The chemical reaction that produces heat and light.
c)
The process of a liquid turning into a gas.
d)
The physical change of matter.
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Nclex Coaching Centre answered |
Combustion is a chemical reaction where a substance reacts with oxygen, producing heat and light. This process is crucial for energy production in various fuels.
What is the main reason water has its maximum density at 4°C?- a) It expands when heated.
- b) It has very low kinetic energy at this temperature.
- c) It contracts when heated from 0°C to 4°
- d) It remains the same density at all temperatures.
Correct answer is option 'C'. Can you explain this answer?
What is the main reason water has its maximum density at 4°C?
a)
It expands when heated.
b)
It has very low kinetic energy at this temperature.
c)
It contracts when heated from 0°C to 4°
d)
It remains the same density at all temperatures.
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Nclex Coaching Centre answered |
Water contracts when heated from 0°C to 4°C, which is unusual for liquids. This contraction increases its density, making it denser at 4°C than at any other temperature. This unique property ensures that ice floats on water, allowing aquatic life to survive in frozen conditions.
Why do birds puff up their feathers in winter?- a) To trap air and retain heat
- b) To facilitate flight
- c) To attract mates
- d) To appear larger
Correct answer is option 'A'. Can you explain this answer?
Why do birds puff up their feathers in winter?
a)
To trap air and retain heat
b)
To facilitate flight
c)
To attract mates
d)
To appear larger
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Nclex Coaching Centre answered |
Birds puff up their feathers to trap air, which acts as an insulator, helping them retain body heat during cold weather. This adaptation is vital for their survival in colder climates.
What is the phenomenon called when a solid changes into a liquid?- a) Sublimation
- b) Condensation
- c) Freezing
- d) Melting
Correct answer is option 'D'. Can you explain this answer?
What is the phenomenon called when a solid changes into a liquid?
a)
Sublimation
b)
Condensation
c)
Freezing
d)
Melting
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Nclex Coaching Centre answered |
The phenomenon where a solid changes into a liquid is known as melting. This occurs at a specific temperature known as the melting point, where the solid's molecules gain enough energy to overcome their fixed positions and move freely as a liquid.
Which process involves a liquid changing to a gas at all temperatures?- a) Freezing
- b) Condensation
- c) Boiling
- d) Evaporation
Correct answer is option 'D'. Can you explain this answer?
Which process involves a liquid changing to a gas at all temperatures?
a)
Freezing
b)
Condensation
c)
Boiling
d)
Evaporation
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Nclex Coaching Centre answered |
Evaporation is the process where a liquid changes to a gas at all temperatures, occurring at the surface of the liquid. It contrasts with boiling, which occurs at a specific temperature throughout the liquid.
How does the boiling point of a liquid change with atmospheric pressure?- a) It increases with increased pressure.
- b) It increases with decreased pressure.
- c) It decreases with increased pressure.
- d) It remains constant regardless of pressure.
Correct answer is option 'A'. Can you explain this answer?
How does the boiling point of a liquid change with atmospheric pressure?
a)
It increases with increased pressure.
b)
It increases with decreased pressure.
c)
It decreases with increased pressure.
d)
It remains constant regardless of pressure.
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Nclex Coaching Centre answered |
The boiling point of a liquid increases with increased atmospheric pressure. When pressure rises, more energy is required for the liquid's vapor pressure to match the atmospheric pressure, thus raising the boiling point.
What happens to the average distance between molecules in a substance when it is heated?- a) It oscillates randomly.
- b) It increases.
- c) It remains unchanged.
- d) It decreases.
Correct answer is option 'B'. Can you explain this answer?
What happens to the average distance between molecules in a substance when it is heated?
a)
It oscillates randomly.
b)
It increases.
c)
It remains unchanged.
d)
It decreases.
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Nclex Coaching Centre answered |
When a substance is heated, the average distance between its molecules increases as they gain kinetic energy and move faster. This increase in distance is responsible for thermal expansion in solids, liquids, and gases.
What is the primary effect of heat energy on the temperature of a solid, liquid, or gas?- a) It increases the temperature.
- b) It decreases the temperature.
- c) It changes the state of matter.
- d) It causes no change in temperature.
Correct answer is option 'A'. Can you explain this answer?
What is the primary effect of heat energy on the temperature of a solid, liquid, or gas?
a)
It increases the temperature.
b)
It decreases the temperature.
c)
It changes the state of matter.
d)
It causes no change in temperature.
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Nclex Coaching Centre answered |
Heat energy increases the temperature of solids, liquids, and gases when it is applied. This effect is fundamental to understanding thermal energy and how it influences various states of matter.
What is the main reason for using a thermos flask?- a) To keep hot liquids hot and cold liquids cold.
- b) To prevent liquids from evaporating.
- c) To measure temperature accurately.
- d) To increase the boiling point of liquids.
Correct answer is option 'A'. Can you explain this answer?
What is the main reason for using a thermos flask?
a)
To keep hot liquids hot and cold liquids cold.
b)
To prevent liquids from evaporating.
c)
To measure temperature accurately.
d)
To increase the boiling point of liquids.
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Nclex Coaching Centre answered |
A thermos flask is designed to keep hot liquids hot and cold liquids cold by using a vacuum between its double walls, which minimizes heat transfer by conduction, convection, and radiation.
What happens to the density of a substance when it is heated?- a) It decreases.
- b) It becomes undefined.
- c) It remains constant.
- d) It increases.
Correct answer is option 'A'. Can you explain this answer?
What happens to the density of a substance when it is heated?
a)
It decreases.
b)
It becomes undefined.
c)
It remains constant.
d)
It increases.
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Nclex Coaching Centre answered |
When a substance is heated, its volume typically increases while its mass remains constant, leading to a decrease in density. This principle explains why hot air rises: as the air heats up, it expands, becomes less dense, and rises above cooler, denser air.
What is the process called when a solid turns into a liquid due to heat?- a) Vaporization
- b) Melting
- c) Condensation
- d) Freezing
Correct answer is option 'B'. Can you explain this answer?
What is the process called when a solid turns into a liquid due to heat?
a)
Vaporization
b)
Melting
c)
Condensation
d)
Freezing
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Nclex Coaching Centre answered |
The process where a solid turns into a liquid because it absorbs heat is known as melting. For instance, ice melts into water at 0°C when it absorbs enough heat.
What is the primary effect of heat on the temperature of a body?- a) It can increase or decrease the temperature depending on heat absorption or loss.
- b) It always increases the temperature.
- c) It always decreases the temperature.
- d) It has no effect on temperature.
Correct answer is option 'A'. Can you explain this answer?
What is the primary effect of heat on the temperature of a body?
a)
It can increase or decrease the temperature depending on heat absorption or loss.
b)
It always increases the temperature.
c)
It always decreases the temperature.
d)
It has no effect on temperature.
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Nclex Coaching Centre answered |
Heat can either increase or decrease the temperature of a body based on the quantity of heat absorbed or released. When a body absorbs heat, its molecules move faster, leading to an increase in average kinetic energy and, consequently, temperature. Conversely, when heat is lost, the molecules slow down, decreasing the temperature.
In which state of matter does thermal expansion occur most significantly?- a) Liquids
- b) Solids
- c) Gases
- d) All states equally
Correct answer is option 'C'. Can you explain this answer?
In which state of matter does thermal expansion occur most significantly?
a)
Liquids
b)
Solids
c)
Gases
d)
All states equally
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Nclex Coaching Centre answered |
Thermal expansion occurs most significantly in gases. Gases have much more space between molecules compared to solids and liquids, allowing a greater increase in volume when heated. This is why gases expand more than liquids and solids under the same temperature increase.
At what temperature does water boil under standard atmospheric pressure?- a) 50°C
- b) 100°C
- c) 150°C
- d) 0°C
Correct answer is option 'B'. Can you explain this answer?
At what temperature does water boil under standard atmospheric pressure?
a)
50°C
b)
100°C
c)
150°C
d)
0°C
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Nclex Coaching Centre answered |
Water boils at 100°C under standard atmospheric pressure. At this temperature, the vapor pressure of the water equals the atmospheric pressure, allowing bubbles of vapor to form throughout the liquid, resulting in boiling.
What is thermal expansion?- a) The process where materials change state without temperature change.
- b) The increase in size of materials when heated.
- c) The process of a material becoming smaller when heated.
- d) The decrease in temperature of materials when heated.
Correct answer is option 'B'. Can you explain this answer?
What is thermal expansion?
a)
The process where materials change state without temperature change.
b)
The increase in size of materials when heated.
c)
The process of a material becoming smaller when heated.
d)
The decrease in temperature of materials when heated.
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Nclex Coaching Centre answered |
Thermal expansion refers to the increase in size of materials when heated. Most materials expand in length, area, or volume as their temperature rises, which is essential in engineering and construction.
Which property of a good thermometric liquid allows it to be effective in measuring temperature?- a) It expands evenly with temperature changes.
- b) It freezes at high temperatures.
- c) It is a poor conductor of heat.
- d) It is opaque and does not change color.
Correct answer is option 'A'. Can you explain this answer?
Which property of a good thermometric liquid allows it to be effective in measuring temperature?
a)
It expands evenly with temperature changes.
b)
It freezes at high temperatures.
c)
It is a poor conductor of heat.
d)
It is opaque and does not change color.
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Nclex Coaching Centre answered |
A good thermometric liquid, such as mercury or alcohol, expands evenly with temperature changes. This property allows for accurate temperature readings along a marked scale.
What is one practical application of thermal expansion in everyday life?- a) Cooling liquids in a refrigerator.
- b) Mixing solids and liquids.
- c) Heating a metal ball to fit through a ring.
- d) Freezing water to make ice.
Correct answer is option 'C'. Can you explain this answer?
What is one practical application of thermal expansion in everyday life?
a)
Cooling liquids in a refrigerator.
b)
Mixing solids and liquids.
c)
Heating a metal ball to fit through a ring.
d)
Freezing water to make ice.
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Nclex Coaching Centre answered |
A practical application of thermal expansion is heating a metal ball so it can fit through a ring. When heated, the ball expands, demonstrating how materials change size with temperature.
What happens to the heat when a substance undergoes a chemical change?- a) It disappears.
- b) It remains the same.
- c) It only increases.
- d) It is absorbed or released.
Correct answer is option 'D'. Can you explain this answer?
What happens to the heat when a substance undergoes a chemical change?
a)
It disappears.
b)
It remains the same.
c)
It only increases.
d)
It is absorbed or released.
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Nclex Coaching Centre answered |
During a chemical change, heat is either absorbed or released, depending on the nature of the reaction. This transfer of energy is crucial for processes such as combustion and respiration.
What does the coefficient of linear expansion represent?- a) The increase in length of a solid per degree of temperature change.
- b) The increase in mass of a solid when heated.
- c) The increase in area of a solid when heated.
- d) The increase in volume of a solid when heated.
Correct answer is option 'A'. Can you explain this answer?
What does the coefficient of linear expansion represent?
a)
The increase in length of a solid per degree of temperature change.
b)
The increase in mass of a solid when heated.
c)
The increase in area of a solid when heated.
d)
The increase in volume of a solid when heated.
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Nclex Coaching Centre answered |
The coefficient of linear expansion quantifies how much a solid's length increases per degree of temperature change. It is a material-specific constant that helps predict how much a material will expand or contract with temperature variations.
What is the effect of increased humidity on the rate of evaporation?- a) It increases the rate of evaporation.
- b) It has no effect.
- c) It decreases the rate of evaporation.
- d) It stops evaporation entirely.
Correct answer is option 'C'. Can you explain this answer?
What is the effect of increased humidity on the rate of evaporation?
a)
It increases the rate of evaporation.
b)
It has no effect.
c)
It decreases the rate of evaporation.
d)
It stops evaporation entirely.
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Nclex Coaching Centre answered |
Increased humidity decreases the rate of evaporation because the air already contains a high amount of water vapor. This reduces the capacity of the air to accept more vapor, slowing down the escape of liquid molecules from the surface.
Which of the following materials is classified as a thermal insulator?- a) Copper
- b) Aluminum
- c) Wool
- d) Iron
Correct answer is option 'C'. Can you explain this answer?
Which of the following materials is classified as a thermal insulator?
a)
Copper
b)
Aluminum
c)
Wool
d)
Iron
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Nclex Coaching Centre answered |
Wool is a thermal insulator because it does not conduct heat well, making it ideal for keeping warmth in during cold weather. Insulators are essential for maintaining temperature in various applications.
Which process describes the change of a solid directly into a gas?- a) Freezing
- b) Sublimation
- c) Evaporation
- d) Melting
Correct answer is option 'B'. Can you explain this answer?
Which process describes the change of a solid directly into a gas?
a)
Freezing
b)
Sublimation
c)
Evaporation
d)
Melting
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Nclex Coaching Centre answered |
The process of a solid changing directly into a gas is called sublimation. For example, dry ice (solid carbon dioxide) sublimates to produce carbon dioxide gas without becoming liquid first. This phenomenon illustrates how some substances can transition between states without passing through all intermediate forms.
What is the purpose of leaving gaps between rail tracks?- a) To reduce noise
- b) To prevent rusting
- c) To allow for thermal expansion
- d) To enhance aesthetics
Correct answer is option 'C'. Can you explain this answer?
What is the purpose of leaving gaps between rail tracks?
a)
To reduce noise
b)
To prevent rusting
c)
To allow for thermal expansion
d)
To enhance aesthetics
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Nclex Coaching Centre answered |
Gaps are left between rail tracks to allow for thermal expansion. As temperatures rise, the metal expands; without gaps, the tracks could bend or buckle, leading to safety hazards.
What is the Kelvin equivalent of 0°C?- a) 0 K
- b) 100 K
- c) 373 K
- d) 273 K
Correct answer is option 'D'. Can you explain this answer?
What is the Kelvin equivalent of 0°C?
a)
0 K
b)
100 K
c)
373 K
d)
273 K
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Nclex Coaching Centre answered |
The Kelvin scale's zero point is equivalent to 0°C, which is 273 K. This conversion is essential for scientific calculations that utilize the absolute temperature scale.
What happens to the volume of a gas when it is heated in a closed container?- a) It evaporates.
- b) It decreases.
- c) It remains the same.
- d) It increases.
Correct answer is option 'D'. Can you explain this answer?
What happens to the volume of a gas when it is heated in a closed container?
a)
It evaporates.
b)
It decreases.
c)
It remains the same.
d)
It increases.
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Nclex Coaching Centre answered |
When a gas is heated in a closed container, its volume increases because the gas molecules move faster and push against the walls of the container more forcefully.
Which of the following is NOT a method of heat transfer?- a) Conduction
- b) Radiation
- c) Conformation
- d) Convection
Correct answer is option 'C'. Can you explain this answer?
Which of the following is NOT a method of heat transfer?
a)
Conduction
b)
Radiation
c)
Conformation
d)
Convection
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Nclex Coaching Centre answered |
Conformation is not a method of heat transfer. The three primary methods are conduction (through solids), convection (through fluids), and radiation (through space).
What is a real-life application of thermal expansion in the construction of bridges?- a) Use of lighter materials
- b) Use of only solid materials
- c) Fixed support structures
- d) Gaps between rail tracks
Correct answer is option 'D'. Can you explain this answer?
What is a real-life application of thermal expansion in the construction of bridges?
a)
Use of lighter materials
b)
Use of only solid materials
c)
Fixed support structures
d)
Gaps between rail tracks
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Nclex Coaching Centre answered |
In bridge construction, small gaps are left between rail tracks to accommodate thermal expansion. These gaps allow the steel rails to expand during hot weather without bending or warping, ensuring safety and structural integrity.
Which of the following statements is true regarding boiling and evaporation?- a) Both occur at the same temperature.
- b) Boiling decreases the temperature of a liquid.
- c) Boiling occurs only at the surface of the liquid.
- d) Evaporation can occur at any temperature.
Correct answer is option 'D'. Can you explain this answer?
Which of the following statements is true regarding boiling and evaporation?
a)
Both occur at the same temperature.
b)
Boiling decreases the temperature of a liquid.
c)
Boiling occurs only at the surface of the liquid.
d)
Evaporation can occur at any temperature.
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Nclex Coaching Centre answered |
Evaporation can occur at any temperature, while boiling happens at a fixed temperature known as the boiling point. During boiling, vapor bubbles form throughout the liquid, unlike evaporation, which only happens at the surface.
What is the term for the heat absorbed or released during a change of state?- a) Kinetic energy
- b) Potential energy
- c) Latent heat
- d) Thermal energy
Correct answer is option 'C'. Can you explain this answer?
What is the term for the heat absorbed or released during a change of state?
a)
Kinetic energy
b)
Potential energy
c)
Latent heat
d)
Thermal energy
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Nclex Coaching Centre answered |
The heat absorbed or released during a change of state is known as latent heat. This energy does not change the temperature of the substance but alters the average potential energy of its molecules, allowing for transitions such as melting or boiling.
Which factor does NOT affect the rate of evaporation?- a) Temperature of the liquid
- b) Humidity of the surrounding air
- c) Color of the liquid
- d) Surface area of the liquid
Correct answer is option 'C'. Can you explain this answer?
Which factor does NOT affect the rate of evaporation?
a)
Temperature of the liquid
b)
Humidity of the surrounding air
c)
Color of the liquid
d)
Surface area of the liquid
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Nclex Coaching Centre answered |
The color of the liquid does not affect the rate of evaporation. However, temperature, surface area, and humidity significantly influence how quickly a liquid can evaporate. Higher temperatures and larger surface areas increase the rate, while higher humidity decreases it.
What does the term "latent heat" refer to?- a) Heat required during a change of state without temperature change
- b) Heat lost during condensation
- c) Heat absorbed during cooling
- d) Heat required to change temperature
Correct answer is option 'A'. Can you explain this answer?
What does the term "latent heat" refer to?
a)
Heat required during a change of state without temperature change
b)
Heat lost during condensation
c)
Heat absorbed during cooling
d)
Heat required to change temperature
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Nclex Coaching Centre answered |
Latent heat is the heat required for a substance to change its state without changing its temperature. This energy alters the potential energy of the molecules, allowing for state changes such as melting or boiling while the temperature remains constant.
Which of the following materials is considered a good conductor of heat?- a) Glass
- b) Plastic
- c) Copper
- d) Wood
Correct answer is option 'C'. Can you explain this answer?
Which of the following materials is considered a good conductor of heat?
a)
Glass
b)
Plastic
c)
Copper
d)
Wood
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Nclex Coaching Centre answered |
Copper is an excellent conductor of heat, which is why it is commonly used in cooking pots and electrical wiring. Good conductors allow heat to flow easily through them.
Which of the following is an example of thermal expansion in everyday life?- a) A solid becoming a liquid at room temperature.
- b) A balloon inflating when heated.
- c) Water freezing in winter.
- d) Ice melting in a drink.
Correct answer is option 'B'. Can you explain this answer?
Which of the following is an example of thermal expansion in everyday life?
a)
A solid becoming a liquid at room temperature.
b)
A balloon inflating when heated.
c)
Water freezing in winter.
d)
Ice melting in a drink.
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Nclex Coaching Centre answered |
A balloon inflating when heated is an example of thermal expansion. As the air inside the balloon heats up, it expands, causing the balloon to inflate. This effect demonstrates the principles of gas expansion when temperature increases.
How does the size of most substances change when heated?- a) They change to a different shape.
- b) They remain the same size.
- c) They contract.
- d) They expand.
Correct answer is option 'D'. Can you explain this answer?
How does the size of most substances change when heated?
a)
They change to a different shape.
b)
They remain the same size.
c)
They contract.
d)
They expand.
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Nclex Coaching Centre answered |
Most substances expand when heated due to increased molecular motion. As temperature rises, the molecules gain kinetic energy and move farther apart, resulting in an increase in size. This phenomenon is referred to as thermal expansion.
What is the effect of temperature on molecular motion in a substance?- a) Temperature has no effect on molecular motion.
- b) Higher temperature increases molecular motion.
- c) Higher temperature slows down molecular motion.
- d) Molecular motion is random and unrelated to temperature.
Correct answer is option 'B'. Can you explain this answer?
What is the effect of temperature on molecular motion in a substance?
a)
Temperature has no effect on molecular motion.
b)
Higher temperature increases molecular motion.
c)
Higher temperature slows down molecular motion.
d)
Molecular motion is random and unrelated to temperature.
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Nclex Coaching Centre answered |
Higher temperatures increase molecular motion because the molecules gain kinetic energy. This increased motion causes them to collide more frequently and move farther apart, leading to phenomena like expansion in solids, liquids, and gases.
What happens to the temperature of a substance when it undergoes evaporation?- a) It increases significantly.
- b) It remains constant.
- c) It fluctuates randomly.
- d) It decreases.
Correct answer is option 'D'. Can you explain this answer?
What happens to the temperature of a substance when it undergoes evaporation?
a)
It increases significantly.
b)
It remains constant.
c)
It fluctuates randomly.
d)
It decreases.
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Nclex Coaching Centre answered |
During evaporation, the temperature of the remaining liquid decreases because the molecules with the highest energy escape, leaving behind lower-energy molecules. This cooling effect is why sweat cools the body.
At what temperature does water boil, transforming from a liquid to a gas?- a) 100°C
- b) 150°C
- c) 0°C
- d) 50°C
Correct answer is option 'A'. Can you explain this answer?
At what temperature does water boil, transforming from a liquid to a gas?
a)
100°C
b)
150°C
c)
0°C
d)
50°C
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Nclex Coaching Centre answered |
Water boils at 100°C, converting from a liquid state to steam (gas) by absorbing heat energy. This boiling point is crucial for various cooking and scientific applications.
Which type of expansion occurs when a solid expands in length due to heating?- a) Cubical expansion
- b) Linear expansion
- c) Superficial expansion
- d) Thermal contraction
Correct answer is option 'B'. Can you explain this answer?
Which type of expansion occurs when a solid expands in length due to heating?
a)
Cubical expansion
b)
Linear expansion
c)
Superficial expansion
d)
Thermal contraction
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Nclex Coaching Centre answered |
Linear expansion occurs when a solid expands in length as it is heated. This principle is applied in various construction and engineering practices to accommodate changes in temperature.
Chapter doubts & questions for Heat - Science for Year 3 2025 is part of Year 3 exam preparation. The chapters have been prepared according to the Year 3 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Year 3 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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