# Ncert Science Class 7 Solutions Chapter 3

## Ncert Science Class 7 Solutions Chapter 3 Heat

Welcome to NCTB Solutions. Here with this post we are going to help 7th class students for the Solutions of NCERT Class 7 Science Book Chapter 3, Heat. Here students can easily find step by step solutions of all the questions in Heat. Also our Expert Science Teacher’s solved all the problems with easily understandable language with proper guidance so that all the students can understand easily. Here in this post students will get chapter 3 solutions. Here all Question Answer are based on NCERT latest syllabus.

Heat Exercise question Solutions :

(1) State similarities and differences between the laboratory thermometer and the clinical thermometer.

Similarities between laboratory and clinical thermometer :

• The both thermometer the laboratory thermometer and the clinical thermometer are near about same and has a same shape and body but not exactly same .
• The both thermometer have a long narrow tube which is made of glass in both of them.
• The both thermometer have bulb like structure at one end each.
• The bulb contains the mercury in both of them which is the main part of this thermometer because as the thermometer is deeped in the hot substance the mercury takes a flow or rise up.
• The mercury rises along the tube which is scaled in Celsius hence used to measure

Difference between laboratory and clinical thermometer :

• Laboratory thermometer :

(i) Name is the thermometer is used to measure the temperature in the laboratory and labs.

(ii) Laboratory the temperature begins from a very low scale to a very high scale hence the range is high from -10 to 110 c.

(iii) Does not has a kink which prevents the back flow of mercury

• Clinical thermometer :

(i) Used in clinics at home etc to check the body temperature

(ii) Used to check the body temperature which is near 30 to 42 c and this range

(iii) Has a kink which prevents the back flow of mercury

(2) Give two examples each of conductors and insulators of heat.

• Conductors these are those substances which are used or has the property of conducting the electricity with them from one point to another point.

Example : iron, copper, aluminum etc.

• Insulators are those substances which don’t let the electricity flow or don’t conduct the electricity with them.

Example : plastic, rubber, wood and etc.

(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.

(a) Temperature

(b) Clinical

(c) Celsius

(e) Conduction

(f) Deep or Dark colours. (like Black, Blue, etc)

(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

(i) The land breeze blows during → (d) night

(ii) The sea breeze blows during the → (c) day

(iii) Dark-colored clothes are preferred during → (b) winter

(iv) Light-colored clothes are preferred during → (a) summer

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

As we all know to conduct a thing there must be good conductor and air is a bad conductor of heat during winter we wear many layer and here the air gets trapped it does not passes through the layers hence the wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

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

The heat is absorbed more in the dark color as compare to light color so in places of hot climate it is advised that the outer walls of houses be painted white because the white color reflects the more heat and absorbs less. The more reflection the less absorption.

(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

Between 30°C and 50°C is the correct answer.

Explanation : As the water is at 30 c and 50 c the water is mixed and the heat will be between 30°C and 50°C because the cold water tries to absorb heat and hot water tries to get cooled hence the heat is between 30°C and 50°C.

(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.

(b) Not flow from iron ball to water or from water to iron ball – is the correct one.

Explanation : An iron ball at 40°C is dropped in a mug containing water at 40°C. The heat will not flow from iron ball to water or from water to iron ball because the heat can transfer when there is difference in heat in both iron ball and water as the heat is same no change will appear.

(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.

(d) Does not become cold is the correct answer.

Explanation : For conduction the conductor should be good conductor as the wood is bad conductor of heat the end will not be cold does not become cold.

(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.