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NCERT Solutions for Class 7 Science Chapter 7 Heat Transfer in Nature

NCERT Solutions for Class 7 Science Chapter 7 Heat Transfer in Nature

Edited By Irshad Anwar | Updated on Jun 27, 2025 08:19 AM IST

Ever wondered how we feel hot or cold and how heat moves from one object to another? That is exactly what Class 7 Science Chapter 7 Heat helps you understand. This chapter explains how heat is transferred (hotter object to a colder), how materials behave when heated, and how we measure temperature. The NCERT Solutions for Chapter 7 are created by expert faculty based on the latest syllabus of CBSE.

These NCERT solutions for class 7 include step-by-step answers to all textbook questions along with proper explanation and cover important topics like conduction, convection, and radiation. With easy language, useful examples, and tips for solving questions, these NCERT solutions for class 7 science help you learn this chapter better and faster. We have also included a clear approach to solving the questions so you can handle them easily and feel confident in exams.

This Story also Contains
  1. NCERT Solutions Heat Transfer in Nature Class 7: Exercise Questions
  2. NCERT Solutions for Class 7 Science Chapter 7: Topics
  3. NCERT Solutions for Class 7 Science Chapter 7: Important Formulae
  4. Approach to solve the NCERT Class 7 Science Chapter 7 Questions
  5. NCERT Solutions for Class 7 Science : Chapter-Wise
NCERT Solutions for Class 7 Science Chapter 7 Heat Transfer in Nature
NCERT Solutions for Class 7 Science Chapter 7 Heat Transfer in Nature

NCERT Solutions Heat Transfer in Nature Class 7: Exercise Questions

Below are the detailed exercise solutions for Class 7 Science Chapter 7 Heat Transfer in Nature. Students can follow these solutions to score well on the final exam.

Q1.(i) Choose the correct option in each case. (i) Your father bought a saucepan made of two different materials, A and B, as shown in Fig. 7.14. The materials A and B have the following properties —

(a) Both A and B are good conductors of heat
(b) Both A and B are poor conductors of heat
(c) A is a good conductor and B is a poor conductor of heat
(d) A is a poor conductor and B is a good conductor of heat


Answer: (c) A is a good conductor and B is a poor conductor of heat

Q1.(ii) Pins are stuck to a metal strip with wax and a burning candle is kept below the rod, as shown in Fig. 7.15. Which of the following will happen?

(a) All the pins will fall almost at the same time
(b) Pins I and II will fall earlier than pins III and IV
(c) Pins I and II will fall later than pins III and IV
(d) Pins II and III will fall almost at the same time

Answer: (b) Pins I and II will fall earlier than pins III and IV
Explanation: Heat travels from the heated end to the other end via conduction. The pins near the flame fall first as the wax melts.

Q1. (iii) A smoke detector is a device that detects smoke and sounds an alarm. Suppose you are fitting a smoke detector in your room. The most suitable place for this device will be:

(a) Near the floor
(b) In the middle of a wall
(c) On the ceiling
(d) Anywhere in the room

Answer:(c) On the ceiling
Explanation: Smoke rises up due to convection, so detectors must be placed at the highest point.

Q2. A shopkeeper serves you cold lassi in a tumbler. By chance, the tumbler had a small leak. You were given another tumbler by the shopkeeper to put the leaky tumbler in it. Will this arrangement help to keep the lassi cold for a longer time? Explain.


Answer: Yes, it will help. The air between the two tumblers acts as an insulator (a poor conductor of heat) and slows down the heat transfer from outside.

Q3. State with reason(s) whether the following statements are True [T] or False [F].
(i) Heat transfer takes place in solids through convection. [ ]
(ii) Heat transfer through convection takes place by the actual movement of particles. [ ]
(iii) Areas with clay materials allow more seepage of water than those with sandy materials. [ ]
(iv) The movement of cooler air from land to sea is called land breeze. [ ]

Answer:(i) False
Reason: In solids, heat transfer happens through conduction, not convection.
(ii) True
Reason: In convection, particles of liquids and gases move to transfer heat.

(iii) False
Reason: Clay has smaller pores than sand, so it allows less seepage.

(iv) True
Reason: At night, land cools faster, and cooler air moves towards the sea.

Q4. Some ice cubes placed in a dish melt into water after sometime. Where do the ice cubes get heat for this transformation?

Answer: When ice cubes are placed in a dish, they start to melt and turn into water. For this transformation to happen, the ice needs to absorb heat energy.

  • The ice cubes get heat from the surrounding environment.
  • This includes heat from the air around them, the surface of the dish, and even the table they are placed on.
  • The heat causes the ice to melt and change into water.
  • This heat makes the ice melt and turn into water.

Q5.A burning incense stick is fi xed, pointing downwards. In which direction would the smoke from the incense stick move? Show the movement of smoke with a diagram.

Answer: When an incense stick is burning and fixed pointing downwards, the smoke will move upwards. This happens because smoke rises due to convection.

As the incense stick burns, it heats the air around it, making the air less dense. The cooler, denser air pushes the hot air (and smoke) upward. So, even if the incense stick is pointing downwards, the smoke will still rise.

Q6. Two test tubes with water are heated by a candle flame as shown in Fig. 7.16. Which thermometers (Fig. 7.16a or Fig. 7.16b) will record a higher temperature? Explain.


Answer:

In the given experiment, the test tube in Fig. 7.16(b), where the thermometer is closer to the flame, will show a higher temperature.

When water is heated by the candle, it becomes hot at the bottom of the test tube. The hot water rises because it is less dense than the cooler water. This movement of water from the bottom to the top is called convection.

Now, let's look at both test tubes:

  • In Fig. 7.16(a): The thermometer is placed higher up, away from the hot water. It does not measure the rising hot water directly. So, it will show a lower temperature.
  • In Fig. 7.16(b): The thermometer is placed in the area where the hot water is rising. Since the hot water is directly in contact with the thermometer, it will measure the higher temperature.

Therefore, the thermometer in Fig. 7.16(b) will show a higher temperature.

Q7.Why are hollow bricks used to construct the outer walls of houses in hot regions?

Answer: Hollow bricks are used because they trap air inside the spaces between the bricks. Air is a poor conductor of heat, meaning it does not allow heat to pass through easily. This helps to reduce heat transfer from the outside to the inside of the house. As a result, the house stays cooler in hot regions, as less heat enters through the walls.

Q8.Explain how large water bodies prevent extreme temperatures in areas around them.

Answer: Large water bodies, such as oceans and seas, help prevent extreme temperatures in nearby areas through the sea and land breeze effect.

Q9. Explain how water seeps through the surface of the Earth and gets stored as groundwater.

Answer:

Water seep through the surface of the Earth:

  • When it rains, water falls to the ground and moves through the soil and rocks. This process is called infiltration.
  • The water travels down through the layers of soil and rocks, filling the gaps and spaces between them.Storage in aquifers:
  • Eventually, the water reaches underground layers called aquifers, which are large areas of rock or soil that can hold water. These aquifers store the water as groundwater.

Thus, water seeps through the soil and rocks into the ground, where it gets stored as groundwater.

Q10. The water cycle helps in the redistribution and replenishment of water on the Earth. Justify the statement.

Answer: The water cycle helps move water around the Earth through evaporation, condensation, and precipitation. It brings rain, fills rivers and lakes, and refills underground water. This way, it redistributes and replenishes water everywhere.

NCERT Solutions for Class 7 Science Chapter 7: Topics

Below are the important topics covered in Class 7 Science Chapter 7 Heat. These topics will help you understand how heat is transferred, the effects of heat, and how materials behave when heated.

7.1 Conduction of Heat
7.2 Convection
7.2.1 Land and Sea Breeze
7.3 Radiation
7.4 Water Cycle
7.4.1 Seepage of water beneath the Earth

NCERT Solutions for Class 7 Science Chapter 7: Important Formulae

Below are the important formulae from Class 7 Science Chapter 7 Heat Transfer in Nature. These formulas will help you in solving questions effectively:

Temperature Conversion:

  • C=(F32)×5/9
  • F=(C×9/5)+32
Background wave

Approach to solve the NCERT Class 7 Science Chapter 7 Questions

To solve questions from Class 7 Science Chapter 7, first identify the topic conduction, convection, radiation, or the water cycle. Remember that heat flows from hot to cold. Use real-life examples like land breeze and sea breeze for convection and explain how water moves through evaporation, condensation, and seepage. Focus on diagrams also, where needed.

NCERT Solutions for Class 7 Science : Chapter-Wise

In addition to the Class 7 Science chapter 7 question answer, students can access comprehensive chapter-wise solutions for Class 7 Science by clicking the link provided below:

NCERT Solutions for Class 7- Subject Wise

Also, check NCERT Books and NCERT Syllabus here

Frequently Asked Questions (FAQs)

1. What is heat transfer?

Heat transfer is the movement of heat from a hotter object to a cooler one.

2. What are the three modes of heat transfer?

The three modes are conduction, convection, and radiation.

3. What is convection?

Convection is the transfer of heat through liquids or gases by the movement of particles.

4. Why do we wear woolen clothes in winter?

Woolen clothes trap heat and prevent it from escaping, keeping us warm.

5. What is sea breeze?

Sea breeze is the cool air that blows from the sea to the land during the day due to unequal heating.

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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