NCERT Solutions for Class 7 Science Chapter 3 Heat

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Last Updated on July 10, 2024 by XAM CONTENT

The NCERT Solutions have been updated for 2024-2025 sessions, with the new NCERT Books. All questions are solved with detailed explanation of each and every questions. In this article, we are providing NCERT Solutions for Class 7 Science Chapter 3 Heat.

NCERT Solutions	Class 7 Science
Session	2024-2025
Useful for	Class 7 Students
Chapter	Heat Chapter 3
No. of Intext Questions	7
Exercise Questions	11
Format	Question-Answer Format

[PDF] Heat Class 7 NCERT Solutions Science Chapter 3

NCERT Solutions

INTEXT QUESTIONS

Page-25

Q. 1. Boojho says, “My left hand tells me that the water in mug  is hot and the right-hand tells me that the same water is cold. What should I conclude?
Ans. Both conclusions are correct relative to each hand. But a single conclusion cannot be drawn from the given information.

Q. 2. Boojho wondered which of the two scales of measuring temperature he should read.
Ans. Paheli told him that India has adopted the Celsius scale and we should read that scale. The other scale with the range 94-108 degrees is the Fahrenheit scale (^oF). It was in use earlier.

Page-26

Q. 3. Paheli measured her body temperature. She got worried as it was not exactly 37^oC.
Ans. The temperature of every person may not be 37^oC. It could be slightly higher or slightly lower. Actually, what we call normal temperature is the average body temperature of a large number of healthy persons.

Page-27

Q. 4. Boojho got a naughty idea. He wanted to measure the temperature of hot milk using a clinical thermometer. Paheli stopped him from doing so.
Ans. The clinical thermometer is designed to measure the temperature of human body only. The temperature
of human body normally does not go below 35^oC or above 42^oC. That is the reason that this thermometer has the range 35^oC to 42^oC whereas the temperature of hot milk is 100^oC.

Q. 5. Boojho now understands why clinical thermometer cannot be used to measure high temperatures. But still wonders whether a laboratory thermometer can be used to measure his body temperature.
Ans. The range of clinical thermometer is 35^oC to 42^oC, hence it cannot be used high temperature. The range of laboratory thermometer is 0^oC to 100^oC so it can be used to measure body temperature also.

Q.6. Boojho wonders why the level of mercury should change at all when the bulb of the thermometer is brought in contact with another object?
Ans. The temperature of other object may not be the same as that of the bulb of the thermometer. When bulb is brought in contact with that object, the temperature of the bulb changes. So, the level of mercury also changes.

Page-29

Q. 7. Paheli asks: “Does it mean that heat will not be transferred if the temperature of two objects is the same?”
Ans. Energy does transfer between the two bodies continuously even if they are at the same temperature. There is always an exchange of packets of energy at the interface of each and everybody. But there is no net energy transfer between the bodies.

EXERCISE QUESTIONS

Q. 1. State similarities and differences between the laboratory thermometer and the clinical thermometer. [NCERT Ex. Q.1, Page 34]

Ans.

Laboratory Thermometer	Clinical Thermometer
Similarities
In this thermometer, mercury is used.	In this too, mercury is used.
In this thermometer, the scale is denoted in Celsius.	In this also, the scale is denoted in Celsius
Dissimilarities
Besides body tempera- ture, it is used for mea- suring the temperature of other objects.	This is used only for measuring human body temperatures.
Its temperature measuring capacity ranges from 10oC to 100oC	Its temperature measuring capacity ranges from 35oC to 42oC only.

Q.2. Give two examples each of conductors and insulators of heat.

[NCERT Ex. Q.2, Page 34]

Ans. Conductors: Aluminium and copper. Insulators: Plastic and wood.

Q.3. Fill in the blanks:
(a) The hotness of an object is determined by its _____________
(b) Temperature of boiling water cannot be measured by _____________thermometer.
(c) Temperature is measured in degree _____________
(d) No medium is required for transfer of heat by the process of _____________
(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of _____________
(f) Clothes of _____________colours absorb more heat better than clothes of light colours.

[NCERT Ex. Q.3, Page 34]

Ans. (a) temperature (b) clinical (c) celsius (d) radiation (e) convection (f) black or dark.

Q.4. Match the following:

(i)	Land breeze blows during	(a)	summer
(ii)	Sea breeze blows during	(b)	winter
(iii)	Dark coloured clothes are preferred during	(c)	day
(iv)	Light coloured clothes are preferred during	(d)	night

[NCERT Ex. Q.4, Page 35]

Ans. (i) (d) (ii) (c) (iii) (b) (iv) (a)

Q. 5. Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

[NCERT Ex. Q.5, Page 35]

Ans. During winter, when we have so many layers of clothing on our body, the air trapped in between two layers of cloth acts as an insulator. This is the reason why wearing more layers of clothing keeps our body warm in winter as compared to just one thick piece of clothing.

Q. 6. Look at given figure. Mark where the heat is being transferred by conduction, by convection and by radiation.

Ans.

Q. 7. In places of hot climate it is advised that the outer walls of houses be painted white. Explain.

[NCERT Ex. Q.7, Page 35]

Ans. In hot season, the outer walls of the houses should be painted white, because white colour reflects back the heat radiation which falls upon it. That is why the rooms remain cool, they do not warm up in summer.

Q. 8. One litre of water at 30^oC is mixed with one litre of water at 50^oC. The temperature of the mixture will be:
(a) 80^oC
(b) more than 50^oC but less than 80^oC
(c) 20^oC
(d) between 30^oC and 50^oC

[NCERT Ex. Q.8, Page 35]

Ans. Option (d) is correct.

Q. 9. An iron ball at 40^oC is dropped in a mug containing water at 40^oC. The heat will:
(a) flow from iron ball to water.
(b) not flow from iron ball to water or from water to iron ball.
(c) flow from water to iron ball.
(d) increase the temperature of both.

[NCERT Ex. Q.9, Page 36]

Ans. Option (b) is correct.

Q. 10. A wooden spoon is dipped in a cup of ice cream. Its other end
(a) becomes cold by the process of conduction.
(b) becomes cold by the process of convection.
(c) becomes cold by the process of radiation.
(d) does not become cold.

[NCERT Ex. Q.10, Page 35]

Ans. Option (d) is correct.

Q. 11. Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
(a) copper bottom makes the pan more durable.
(b) such pans appear colourful.
(c) copper is a better conductor of heat than the stainless steel.
(d) copper is easier to clean than the stainless steel.

[NCERT Ex. Q.11, Page 36]

Ans. Option (c) is correct.

Also check

• NCERT Solutions for Class 7 Science Chapter 3 Heat
• NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals
• NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants

NCERT Solutions are available on many different websites, but they are not updated. we update our content regularly so that student be prepared as per the latest syllabus and pattern. In this NCERT Solution series, we are providing latest solutions for class 6 to 12 new NCERT Books.

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