Selina solutions for Concise Physics [English] Class 7 ICSE chapter 5 - Heat [Latest edition]

Write true or false for a given statement.

On touching a lump of ice, we feel cold because some heat passes from our body to the ice.

Write true or false for a given statement.

Heat flows from a body at a high temperature to a body at a low temperature when they are kept in contact. 

Write true or false for a given statement.

All solids expand by the same amount when heated to the same rise in temperature.

Write true or false for a given statement.

Telephone wires are kept tight between the two poles in summer.

Write true or false for a given statement.

Equal volumes of different liquids expand by different amounts when they are heated to the same rise in temperature.

Write true or false for a given statement.

Solids expand the least and gases expand the most on being heated.

Write true or false for a given statement.

A mercury thermometer makes use of the property of the expansion of liquids on heating.

Write true or false for a given statement.

Kerosene contracts on heating.

Write true or false for a given statement.

Water is a bad conductor of heat.

Write true or false for a given statement.

Medium is necessary for the transfer of heat by radiation.

Write true or false for a given statement.

Land and sea breezes are convection currents of cold and warm air.

Write true or false for a given statement.

Liquids are heated by conduction and radiation.

Write true or false for a given statement.

Black surfaces are the poor absorbers of heat radiations.

Fill in the blank

Heat is a form of _______.

 Fill in the blank

_________ determines the degree of hotness or coldness of a body.

Fill in the blank

On heating a body, its temperature _______.

 Fill in the blank

 We use a ________ for measuring the temperature of a body.

 Fill in the blank

The S.I. unit of temperature is ________.

Fill in the blank

In a thermometer, the commonly used liquid is _______

Fill in the blank

The temperature of a normal human body is ________.

Fill in the blank

A person is said to have fever if his body temperature is more than _________

Fill in the blank

A hot metallic piece is placed in tap water contained in a bucket. Heat will flow from _______ to _________

Fill in the blank

The temperature of boiling water is _______

Fill in the blank

Liquids expand _______ than the solids.

 Fill in the blank

 Gases expand _______ than the liquids.

Fill in the blank

Heat transfer in solids is by ______

Fill in the blank

Heat transfer in liquids and gases is by ________.

Fill in the blank

Metals are _______ of heat.

Fill in the blank

Still air is an __________ of heat.

Fill in the blank

Black and dull surfaces are ______ of heat.

Match the following

Select the correct alternative

If we add a lump of ice to a tumbler containing water,

Select the correct alternative

The temperature of pure melting ice is

Select the correct alternative

A thermometer uses

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Which of the statement is correct

Select the correct alternative

Heat in a liquid is transferred by

Select the correct alternative

In the process of convection, heat travel

Select the correct alternative

The vacuum kept in between the walls of a thermos flask reduces the heat transfer by

What is heat ? State its S.I. unit.

What is meant by the term temperature.

State the three units of temperature.

Name the instrument used to measure the temperature of a body.

Name two scales of temperature. How are they interrelated?

How is the size of a degree defined on a Celsius scale ?

How is the size of a degree defined on a Fahrenheit scale?

State the temperature of ice point on the Celsius scale.

State the temperature of steam point on the Celsius scale.

Write down the temperature of the lower fixed point on the Fahrenheit scale.

Write down the temperature of upper fixed point,, on the Fahrenheit scale.

What is the Celsius scale of temperature ?

What is the Fahrenheit scale of temperature ?

What is the Kelvin scale of temperature? 

The fig. shows a glass tumbler containing hot milk which is placed in a tub of cold water. State the direction in which heat will flow.

Draw a neat labelled diagram of a laboratory thermometer.

Write down the body temperature of a healthy person.

What do you understand by thermal expansion of a substance ?

Name two substances which expand on heating.

Why do telephone wires sag in summer ?

Iron rims are heated before they are fixed on the wooden wheels. Explain the reason.

Why are gaps left between successive rails on a railway track ?

A glass stopper stuck in the neck of a bottle can be removed by pouring hot water on the neck of the bottle. Explain why ?

Why is a cement floor laid in small pieces with gaps in between?

One end of a steel girder in a bridge is not fixed, but is kept on roliers. Give the reason.

Describe one experiment to show that liquids expand on heating.

State one application of thermal expansion of liquids.

Describe an experiment to show that air expands on heating.

An empty glass bottle is fitted with a narrow tube at its mouth. The open end of the tube is kept in a beaker containing water. When the bottle is heated, bubbles of air are seen escaping into the water. Explain the reason. 

State which expands more, when heated to the same temperature : solid, liquid or gas ?

Name the three modes of transfer of heat.

Name the mode of transfer of heat in the following :
(a) solid,
(b) liquid,
(c) gas
(d) vacuum

What are the good and bad conductors of heat ? Give two examples of each.

Name a liquid which is a good conductor of heat.

Name a solid which is a good conductor of heat.

Select good and bad conductors of heat from the following:
copper, mercury, wood, iron, air, saw-dust, cardboard, silver, plastic, wool.

Why is an oven made of double walls with the space in between filled with cork ?

Why do we use cooking utensils made up of copper.

Why is a tea kettle provided with an ebonite handle?

In summer, ice is kept wrapped in a gunny bag. Explain the reason.

Explain why  we wear woolen clothes in winter.

Explain why  the water pipes are covered with cotton during very cold weather.

Why are quilts filled with fluffy cotton?

State the direction of heat transfer by way of convection.

Why is a ventilator provided in a room?

Why are chimneys provided over furnace in factories?

What are the land and sea breezes? Explain their formation.

Why is the freezing chest in a refrigerator fitted near its top?

Explain briefly the process of heat transfer by radiation.

Give one example of heat transfer by radiation.

Why do we prefer to wear white or light coloured clothes in summer and black or dark coloured clothes in winter ?

The bottom of a cooking utensil is painted black. Give the reason.

Draw a labelled diagram of a thermo flask. Explain how the transfer of heat by conduction, convection and radiation is reduced to a minimum in it.

The temperature of a body rises by 1°C. What is the corresponding rise on the (a) Fahrenheit scale (b) Kelvin scale?

The temperature rises by 18°F. What is the rise on the Celsius scale?

Convert 5°F to the Celsius scale.

Convert 40°C to the (a) Fahrenheit scale (b) Kelvin Scale.

Convert – 40°F to the Celsius scale.