NCERT Solutions for Class 7 Science Chapter 3 Heat

This chapter covers important ideas such as clinical and laboratory thermometers, conductors and insulators, conduction, convection, radiation, sea breeze, land breeze and the effect of colour on heat absorption. The questions also connect these concepts with everyday examples such as cooking utensils, clothes, houses and hot and cold water.

These Class 7 Science Heat question answers are useful for homework, revision and exam preparation. Along with the textbook exercise answers, this page includes short questions, important questions, MCQs, extra practice questions and a worksheet with answers.

Chapter note: This page follows the older NCERT Class 7 Science chapter Heat, which matches the search intent behind this URL and the GSC queries. If your school currently uses the newer Curiosity textbook, check your textbook chapter number before using these solutions.

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Class 7 Science Chapter 3 Heat: Quick Overview

Topic	What you learn
Heat	How heat moves from a hotter object to a colder object
Temperature	How hotness or coldness is measured
Thermometers	Clinical and laboratory thermometers
Conductors	Materials that allow heat to pass through easily
Insulators	Materials that slow down the transfer of heat
Conduction	Transfer of heat mainly through solids
Convection	Transfer of heat through moving liquids and gases
Radiation	Transfer of heat without requiring a medium
Sea breeze	Movement of air from sea towards land during the day
Land breeze	Movement of air from land towards sea at night

Class 7 Science Chapter 3 Heat Questions and Answers

Question 1: State the similarities and differences between a clinical thermometer and a laboratory thermometer.

Answer:

Both thermometers are used to measure temperature and have a glass tube with a bulb containing a temperature-sensitive liquid such as mercury in the traditional NCERT description.

Clinical thermometer	Laboratory thermometer
Used to measure human body temperature	Used to measure the temperature of substances
Usually has a range of about 35°C to 42°C	Usually has a wider range, about -10°C to 110°C
Has a kink or constriction near the bulb	Does not have this kink
The kink helps retain the reading after removal	The liquid level can fall when the thermometer is removed from the substance
Can be tilted while taking a reading	Should generally be kept upright while taking a reading

The important difference is that a clinical thermometer is designed for body temperature, while a laboratory thermometer is designed to measure the temperature of other substances.

Question 2: Give two examples each of conductors and insulators of heat.

Answer:

Conductors: Copper and aluminium

Insulators: Wood and plastic

Conductors allow heat to pass through them relatively easily. Insulators do not allow heat to pass through them easily.

Question 3: Fill in the blanks.

(a) The hotness of an object is determined by its ________.

Answer: Temperature

(b) Temperature of boiling water cannot be measured by a ________ thermometer.

Answer: Clinical

(c) Temperature is measured in degree ________.

Answer: Celsius

(d) No medium is required for transfer of heat by the process of ________.

Answer: Radiation

(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ________.

Answer: Conduction

(f) Clothes of ________ colours absorb heat better than clothes of light colours.

Answer: Dark

These answers correspond to the standard Heat exercise questions.

Question 4: Match the following.

Answer:

Column A	Correct match
Land breeze blows during	Night
Sea breeze blows during	Day
Heat transfer in solids	Conduction
Heat transfer in liquids and gases	Convection
Heat from the Sun reaches Earth by	Radiation

Question 5: Wearing more layers of clothes during winter keeps us warmer than wearing only one thick piece of clothing. Why?

Answer:

The layers of clothing trap air between them. Air is a poor conductor of heat, so the trapped air slows down the transfer of heat from our body to the surroundings.

Therefore, several thin layers can help keep the body warm.

Question 6: Identify places or situations where heat is transferred by conduction, convection and radiation.

Answer:

• Conduction: A metal spoon becoming hot when placed in hot tea.
• Convection: Hot water circulating while it is heated.
• Radiation: Heat from the Sun reaching Earth.

A single situation can sometimes involve more than one mode of heat transfer, but these examples show the main process involved.

Question 7: Why are buildings in hotter regions often painted white?

Answer:

Light-coloured surfaces, including white surfaces, reflect more of the Sun's radiation than dark surfaces. As a result, the outer walls absorb less heat and the building can remain relatively cooler.

Question 8: One litre of water at 50°C is mixed with one litre of water at 30°C. What will be the temperature of the mixture?

1. 80°C
2. Less than 80°C but greater than 50°C
3. 20°C
4. Between 50°C and 30°C

Answer: 4. Between 50°C and 30°C

When equal amounts of water at 50°C and 30°C are mixed, heat flows from the hotter water to the cooler water until they approach the same temperature. Assuming no heat is lost to the surroundings, the final temperature would be 40°C.

Question 9: An iron ball at 40°C is dropped into a mug containing water at 40°C. What will happen to the heat?

1. Heat will flow from the iron ball to the water.
2. Heat will not flow from the water to the iron ball or from the iron ball to the water.
3. Heat will flow from the water to the iron ball.
4. Both temperatures will increase.

Answer: 2. Heat will not flow from the water to the iron ball or from the iron ball to the water.

Heat flows because of a temperature difference. Since both objects are at 40°C, there is no temperature difference to drive heat transfer between them.

Question 10: A wooden spoon is dipped into ice-cold water. What happens to its other end?

1. It becomes cold due to convection.
2. It becomes cold due to radiation.
3. It becomes cold due to conduction.
4. It does not become cold quickly.

Answer: 4. It does not become cold quickly.

Wood is a poor conductor of heat. Therefore, heat does not pass through the spoon easily.

Question 11: Why are stainless-steel pans often provided with copper bottoms?

1. They look more colourful.
2. Copper is a much better conductor of heat than stainless steel.
3. Copper is easier to clean.
4. Copper makes the pan more durable.

Answer: 2. Copper is a much better conductor of heat than stainless steel.

Copper conducts heat efficiently, helping heat spread across the bottom of the pan.

Also Read: NCERT Solutions for Class 7 History Chapter 1 Tracing Changes through a Thousand Years

Heat Class 7: Important Concepts

What is heat?

Heat is energy transferred from a hotter object to a colder object because of a temperature difference.

For example, when a cold metal spoon is placed in hot soup, energy moves from the hotter soup towards the cooler spoon.

What is temperature?

Temperature tells us how hot or cold an object is.

A thermometer is used to measure temperature. In school-level science, temperature is commonly expressed in degrees Celsius (°C).

What is a thermometer?

A thermometer is an instrument used to measure temperature.

A clinical thermometer is designed for measuring body temperature, while a laboratory thermometer is used for measuring the temperature of substances in laboratory experiments.

Conduction, Convection and Radiation

Heat can be transferred in different ways.

Conduction

Conduction is the transfer of heat through a substance without the bulk movement of the substance.

It is particularly important in solids.

Example: One end of a metal spoon becomes hot when the other end is placed in hot water.

Metals such as copper and aluminium are good conductors of heat.

Convection

Convection is the transfer of heat through the movement of a fluid, such as a liquid or gas.

When a fluid is heated, the warmer part generally becomes less dense and rises while cooler fluid moves down to take its place.

Example: Water circulates when heated in a vessel.

Radiation

Radiation is the transfer of heat that does not require a material medium.

Example: Energy from the Sun reaches Earth through radiation.

Conductors and Insulators of Heat

Materials behave differently when heat passes through them.

Good conductors

Good conductors allow heat to pass through them relatively easily.

Examples:

• Copper
• Aluminium
• Iron
• Steel

This is why metals are commonly used in cooking utensils.

Insulators

Insulators slow down the transfer of heat.

Examples:

• Wood
• Plastic
• Rubber
• Wool

Pan handles are often made from materials that conduct heat poorly so that they are safer to hold.

Why Do We Wear Different Clothes in Summer and Winter?

Light-coloured clothes in summer

Light colours reflect a greater proportion of sunlight than dark colours. This is one reason light-coloured clothes are preferred in hot weather.

Woollen clothes in winter

Wool traps air within its fibres. Since air is a poor conductor of heat, the trapped air slows the loss of body heat.

This helps keep us warm.

Sea Breeze and Land Breeze

Sea breeze and land breeze are examples of convection caused by unequal heating of land and water.

Sea breeze

During the day, land heats up faster than water.

The air above the warmer land becomes warmer and rises. Cooler air from over the sea moves towards the land.

This movement of air is called a sea breeze.

Land breeze

At night, land cools faster than water.

The air over the relatively warmer sea rises, while cooler air from the land moves towards the sea.

This is called a land breeze.

Also Read: NCERT Solutions Class 7 Science Chapter 4 Acids, Bases and Salts

Class 7 Science Heat Short Question Answers

What is the normal temperature of the human body?

The commonly used reference value for normal human body temperature is around 37°C, although normal body temperature can vary from person to person and during the day.

Why can we not use a clinical thermometer to measure boiling water?

A clinical thermometer is designed for the relatively narrow range of human body temperatures. Boiling water is around 100°C at standard atmospheric pressure, which is far outside the normal range of a clinical thermometer.

Why is copper used at the bottom of some cooking pans?

Copper is a good conductor of heat, so it helps distribute heat efficiently across the base of the pan.

Why does a metal spoon become hot in hot tea?

Heat travels through the metal spoon by conduction from the hotter part towards the cooler part.

Why does a wooden spoon not become hot as quickly as a metal spoon?

Wood is a poor conductor of heat, so heat travels through it much more slowly than through a metal spoon.

Why do dark clothes absorb more heat?

Dark surfaces generally absorb more radiation than light-coloured surfaces.

Why does heat from the Sun reach Earth?

Heat from the Sun reaches Earth through radiation, which does not require a material medium.

Why do several layers of clothing keep us warm?

The layers trap air, and air is a poor conductor of heat. This reduces the rate at which body heat escapes.

Class 7 Science Chapter 3 Heat Important Questions

1. What is the difference between heat and temperature?

Heat is energy transferred because of a temperature difference. Temperature is a measure of how hot or cold an object is.

2. Why does heat move from a hot object to a cold object?

Heat naturally transfers from a region of higher temperature to a region of lower temperature until thermal equilibrium is approached.

3. What are the three methods of heat transfer?

The three methods are:

• Conduction
• Convection
• Radiation

4. Which method transfers heat through solids?

Conduction is the main method of heat transfer through solids.

5. Which method occurs in liquids and gases?

Convection occurs through the movement of liquids and gases.

6. Which method does not require a medium?

Radiation does not require a material medium.

7. Why are metals used to make cooking vessels?

Metals such as copper and aluminium conduct heat efficiently, allowing heat to reach the food.

8. Why are pan handles often made of plastic or wood?

Plastic and wood are poor conductors of heat, so they reduce the amount of heat transferred to the handle.

Class 7 Heat Extra Questions and Answers

Question 1: A metal rod has one end placed in a flame. After some time, the other end becomes warm. Which process is responsible?

Answer: Conduction. Heat travels through the metal from the hotter end towards the cooler end.

Question 2: Why does hot air rise?

Answer: Heating makes air expand and become less dense. The warmer, less dense air rises while cooler, denser air moves down.

Question 3: Why does a woollen blanket keep us warm?

Answer: Wool traps air, and air is a poor conductor of heat. The trapped air slows the loss of body heat.

Question 4: Why does a steel spoon become hotter than a wooden spoon when both are placed in hot water?

Answer: Steel conducts heat much better than wood, so heat travels through the steel spoon more quickly.

Question 5: Why can we feel the warmth of a fire even without touching it?

Answer: Heat reaches us from the fire through radiation. Warm air can also transfer heat by convection.

Question 6: Why is ventilation important in a house?

Answer: Ventilation allows warm air to escape and cooler air to enter. The movement of air can improve circulation and comfort.

Question 7: What happens when two objects at different temperatures are kept in contact?

Answer: Heat flows from the hotter object to the colder object until their temperatures become closer and eventually reach thermal equilibrium.

Question 8: Why should a laboratory thermometer not be held by its bulb while taking a reading?

Answer: Holding the bulb can transfer heat from the hand to the thermometer and affect the temperature reading.

Question 9: Why does the temperature of an object stop changing after sufficient time when it is kept in a room?

Answer: The object exchanges heat with the surroundings until its temperature approaches that of the surroundings.

Question 10: Give one example each of conduction, convection and radiation.

Answer:

• Conduction: A metal spoon becoming hot in soup.
• Convection: Circulation of water while it is heated.
• Radiation: Heat from the Sun reaching Earth.

Class 7 Science Heat MCQs

1. Which instrument is used to measure temperature?

1. Barometer
   B. Thermometer
   C. Ammeter
   D. Speedometer

Answer: B. Thermometer

2. Which material is a good conductor of heat?

1. Wood
   B. Plastic
   C. Copper
   D. Rubber

Answer: C. Copper

3. Which process does not require a material medium?

1. Conduction
   B. Convection
   C. Radiation
   D. Evaporation

Answer: C. Radiation

4. Heat transfer through most solids mainly occurs by:

1. Convection
   B. Conduction
   C. Radiation
   D. Reflection

Answer: B. Conduction

5. Which is a poor conductor of heat?

1. Copper
   B. Aluminium
   C. Iron
   D. Wood

Answer: D. Wood

6. Sea breeze generally occurs during:

1. Day
   B. Night
   C. Midnight only
   D. Winter only

Answer: A. Day

7. Land breeze generally occurs during:

1. Day
   B. Night
   C. Noon only
   D. Summer only

Answer: B. Night

8. Which thermometer is designed to measure human body temperature?

1. Laboratory thermometer
   B. Clinical thermometer
   C. Rain gauge
   D. Barometer

Answer: B. Clinical thermometer

9. Why are light-coloured clothes preferred in hot weather?

1. They absorb more heat.
   B. They reflect more radiation.
   C. They produce heat.
   D. They conduct heat better.

Answer: B. They reflect more radiation.

10. Heat from the Sun reaches Earth mainly by:

1. Conduction
   B. Convection
   C. Radiation
   D. Diffusion

Answer: C. Radiation

Class 7 Science Heat Worksheet

Questions

1. Define temperature.
2. Name two conductors of heat.
3. Name two insulators of heat.
4. What is conduction?
5. What is convection?
6. What is radiation?
7. Why does a metal spoon become hot in hot tea?
8. Why are woollen clothes useful in winter?
9. What causes a sea breeze?
10. Why are light-coloured clothes preferred in summer?
11. Why is copper used in some cooking utensils?
12. What happens when two objects at the same temperature are brought into contact?
13. Why can radiation travel through empty space?
14. Give one everyday example of convection.
15. State one difference between a clinical and laboratory thermometer.

Answer Key

1. Temperature is a measure of how hot or cold an object is.
2. Copper and aluminium.
3. Wood and plastic.
4. Conduction is the transfer of heat through a substance, especially a solid, without bulk movement of the substance.
5. Convection is heat transfer through the movement of a fluid.
6. Radiation is heat transfer that does not require a material medium.
7. Heat travels through the metal by conduction.
8. Wool traps air, which is a poor conductor of heat.
9. Unequal heating of land and sea causes air movement, producing a sea breeze during the day.
10. Light colours reflect more radiation than dark colours.
11. Copper conducts heat well.
12. There is no net heat transfer between them if they remain at the same temperature.
13. Radiation does not require a material medium.
14. Circulation of water while heating it.
15. A clinical thermometer is designed for body temperature, while a laboratory thermometer is used to measure the temperature of substances over a wider range.

Class 7 Science Chapter 3 Heat Activities and Projects

Activity 1: Observe heat conduction

Take a metal spoon and place one end in warm water. Carefully observe the other end after some time.

Observation: The handle gradually becomes warmer.

Reason: Heat travels through the metal by conduction.

Activity 2: Observe convection

Heat water in a transparent container and observe the movement of the water as it warms.

Observation: Water circulates as different portions of the water are heated.

Reason: The movement occurs because of convection.

Activity 3: Observe radiation

Stand at a safe distance from a source of warmth such as sunlight or a warm object.

Observation: You can feel warmth without touching the source.

Reason: Heat can reach you through radiation.

Activity 4: Compare conductors and insulators

Place similar spoons made from different materials in warm water and compare how quickly their handles become warm.

Conclusion: Materials differ in their ability to conduct heat.

Quick Revision: Heat Class 7

Remember these points before an exam:

• Temperature tells us how hot or cold an object is.
• A thermometer is used to measure temperature.
• A clinical thermometer is designed for body temperature.
• A laboratory thermometer has a wider temperature range.
• Copper and aluminium are good conductors.
• Wood and plastic are poor conductors.
• Conduction is important in solids.
• Convection occurs in liquids and gases.
• Radiation does not require a material medium.
• Heat generally moves from a hotter object to a colder object.
• Several layers of clothes trap air and reduce heat loss.
• Dark colours absorb more radiation than light colours.
• Sea breeze occurs during the day.
• Land breeze occurs at night.
• Heat from the Sun reaches Earth by radiation.

Class 7 Science Chapter 3 Heat PDF

If you want to keep these Class 7 Science Heat question answers as a PDF, use your browser's Print → Save as PDF option.

This page includes the chapter questions, short answers, important questions, extra questions, MCQs and worksheet practice in one place.

If your school is using the current NCERT Curiosity textbook, check the chapter title and number before using an older Heat PDF because the Class 7 Science chapter sequence has changed. The current NCERT structure places Heat Transfer in Nature in Chapter 7.