NCERT Solutions for Class 7 Science Chapter 4 Heat

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Written by Team Trustudies
Updated at 2021-02-11


NCERT solutions for class 7 Science Chapter 4 Heat Exercise

Q.1 State similarities and differences between the laboratory thermometer and the clinical thermometer.



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

Similarities:
(i) Both thermometers consist of long narrow uniform glass tubes.
(ii) Both have a bulb at one end.
(iii) Both contain mercury in bulb.
(iv) Both use Celsius scale on the glass tube.
Differences:
(i) A clinical thermometer reads temperature 35°C to 45°C while the range of laboratory thermometer is -10°C to 110°C.
(ii) Clinical thermometer has a kink near the bulb while there is no kink in the laboratory thermometer.
Due to kink mercury does not fall down on its own in clinical thermometer.

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



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

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 a _____________ 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 Solutions for Class 7 Science Chapter 4 Heat


Answer :

(a) The hotness of an object is determined by its __temperature__.
(b) Temperature of boiling water cannot be measured by a __clinical__ thermometer.
(c) Temperature is measured in degree __Celcius__.
(d) No medium is required for transfer of heat by the process of __radiation__.
(e) A cold steel spoon is dipped in a cup of hot milk. Heat is transferred to its other end by the process of __conduction__.
(f ) Clothes of __dark__ colours absorb more heat better than clothes of light colours.

Q.4 Match the following :
Column-I. Column-II
(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 Solutions for Class 7 Science Chapter 4 Heat


Answer :

Column-I. Column-II
(i) The land breeze blows during?(d) night
(ii) The sea breeze blows during ? (c) day
(iii) Dark coloured clothes
are preferred during. ?. (b) winter (iv) Light coloured clothes
are preferred during?. (a) summer

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



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

More layers of clothing keep us warm in winters as they have a lot of space between them. This space gets filled up with air. Air is a bad conductor, it does not allow the body heat to escape out.

Q.6 Look at figure 4.6. Mark where the heat is being transferred by conduction, by convection and by radiation



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

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



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

In places of hot climate, it is advised to paint the outer walls of houses as white because a light colour such as white reflects back most of the heat that falls on it. Hence, a light colour tends to keep the house cool.

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



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

(d) between 30°C and 50°C

Q.9 An iron ball at 40°C is dropped in a mug containing water at 40°C. 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 Solutions for Class 7 Science Chapter 4 Heat


Answer :

(b) not flow from iron ball to water or from water to iron ball

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 Solutions for Class 7 Science Chapter 4 Heat


Answer :

(d) does not become cold

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 stainless steel.
(d) copper is easier to clean than stainless steel.



NCERT Solutions for Class 7 Science Chapter 4 Heat


Answer :

(c) copper is a better conductor of heat than stainless steel.



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