NCERT Solutions for Class 7 Science Chapter 4 Heat

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Written by Team Trustudies
Updated at 2021-05-07


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:

1. Long narrow glass tubes.
2. Both have a bulb at one end.
3. Contain mercury in the bulb.
4. Use the Celsius scale on the glass tube.
5. Both thermometers are used to measure temperature.

Differences:

1. A clinical thermometer reads temperature 35°C to 45°C while the range of laboratory thermometer is -10°C to 110°C.

2. The clinical thermometer has a kink near the bulb while there is no kink in the laboratory thermometer.

3. A clinical thermometer is used to measure human body temperature whereas a laboratory thermometer is used to measure the temperature of another object which has a higher temperature than human body temperature.

4. The least count of both the thermometers is different.

5. The clinical thermometer is can be tilted while reading the temperature values whereas the laboratory thermometers need to be kept upright.

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 colors absorb more heat better than clothes of light colors.

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 :

1. More layers of clothing actually keep us warmer in winters as they have a lot of space between them.

2. As air is a bad conductor of heat it does not allow the escape of the heat from the body.
Air gets trapped in-between layers.

3. This layer prevents our body heat from escaping from the surroundings.

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 :

1. In places of hot climate, it is advised to paint the outer walls of houses white because
a light color such as white reflects back most of the heat that falls on it.

2. White is a poor absorber of heat and a very less amount of heat is absorbed by the walls.
It keeps the inside cool even if there is a hot climate outside the house.

3. Therefore, a light color 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

Because:Hot water loses the heat and simultaneously cold water gains heat this keeps the temperature in 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

Because: Both of them have the same temperature of 40°C.

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

Because: Wood is a bad conductor of heat.

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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