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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.
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
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.
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.
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:
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:
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.
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
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:
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.
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:
Also, check NCERT Books and NCERT Syllabus here
Heat transfer is the movement of heat from a hotter object to a cooler one.
The three modes are conduction, convection, and radiation.
Convection is the transfer of heat through liquids or gases by the movement of particles.
Woolen clothes trap heat and prevent it from escaping, keeping us warm.
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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