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# Selina solutions for Class 9 Physics chapter 6 - Heat and Energy

## Chapter 6: Heat and Energy

Exercise - 6(A)Exercise - 6(B)Exercise - 6(C)Exercise - 6(D)

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(A) [Pages 129 - 130]

Exercise - 6(A) | Q 1 | Page 129

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

Exercise - 6(A) | Q 2 | Page 129

Two bodies at different temperatures are placed in contact. State the direction in which the heat will flow.

Exercise - 6(A) | Q 3 | Page 129

Name the S.I. unit of heat and how is it related to the unit calorie?

Exercise - 6(A) | Q 4 | Page 129

Define temperature and write its S.I. unit.

Exercise - 6(A) | Q 5 | Page 129

Why does a piece of ice when touched with hand , appear cool ? Explain .

Exercise - 6(A) | Q 6 | Page 129

Distinguish between heat and temperature.

Exercise - 6(A) | Q 7 | Page 129

What do you understand by thermal expansion of a substance ?

Exercise - 6(A) | Q 8 | Page 129

Name two substances which expands on heating.

Exercise - 6(A) | Q 9 | Page 129

Name two substances which contract on heating.

Exercise - 6(A) | Q 10 | Page 129

What do you mean by the anomalous expansion of water?

Exercise - 6(A) | Q 11 | Page 129

At what temperature is the density of water is maximum? State its value.

Exercise - 6(A) | Q 12 | Page 129

State the volume changes that you will observe when a given mass of water is heated from 0°C to 10°C. Sketch a temperature-volume graph to show the behaviour.

Exercise - 6(A) | Q 13 | Page 129

Draw a graph to show the variation in density of water with temperature in the range from 0°C to 10°C.

Exercise - 6(A) | Q 14 | Page 129

A given mass of water is cooled from 10°C to 0°C. State the volume changes you will observe. Represent these changes on a temperature-volume graph.

Exercise - 6(A) | Q 15 | Page 130

Describe an experiment to show that water has maximum density at 4°C. What important consequences follow this peculiar property of water? Discuss the importance of this phenomenon in nature.

Exercise - 6(A) | Q 16 | Page 130

A deep pond of water has its top layer frozen during winter. State the expected temperature of water layer (i) Just in contact with ice and (ii) At the bottom of pond.

Exercise - 6(A) | Q 17 | Page 130

Draw a diagram showing the temperature of various layers of water in an ice covered pond.

Exercise - 6(A) | Q 18.1 | Page 130

Explain the following

Water pipes in colder countries often burst in winter.

Exercise - 6(A) | Q 18.2 | Page 130

Explain the following

In winter, water tanks (or ocean) start freezing from the surface and not from the bottom.

Exercise - 6(A) | Q 18.3 | Page 130

Explain the following

Fishes survive in ponds even when the atmospheric temperature is well below 0°C.

Exercise - 6(A) | Q 18.4 | Page 130

Explain the following

A hollow glass sphere which floats with its entire volume submerged in water at 4°C, sinks when water is heated above 4°C.

Exercise - 6(A) | Q 18.5 | Page 130

Explain the following

A glass bottle completely filled with water and tightly closed at room temperature is likely to burst when kept in the freezer of a refrigerator.

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(A) [Page 130]

Exercise - 6(A) | Q 1 | Page 130

Calorie is the unit of :

• Heat

• Work

• Temperature

• food

Exercise - 6(A) | Q 2 | Page 130

1 J equals to :

• 0.24 cal

• 4.18 cal

• 1 cal

• 1 kcal

Exercise - 6(A) | Q 3 | Page 130

S.I. unit of temperature is :

• Cal

• Joule

• Celsius

• kelvin

Exercise - 6(A) | Q 4 | Page 130

Water is cooled from 4 °C to 0 °C. It will :

• contract

• expand

•  first contract, then expand

• first expand, then contract

Exercise - 6(A) | Q 5 | Page 130

Density of water is maximum at :

•  0°C

• 100°C

• 4°C

• 15°C

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(B) [Page 132]

Exercise - 6(B) | Q 1 | Page 132

What is an ecosystem ? Name its two components .

Exercise - 6(B) | Q 2 | Page 132

What is the source of energy for all ecosystems?

Exercise - 6(B) | Q 3 | Page 132

State the importance of green plants in an ecosystem.

Exercise - 6(B) | Q 4 | Page 132

Differentiate between the producers and consumers.

Exercise - 6(B) | Q 5 | Page 132

State the functions of decomposers in an ecosystem.

Exercise - 6(B) | Q 6 | Page 132

What is a food chain?

Exercise - 6(B) | Q 7 | Page 132

Draw a simple diagram showing a food chain.

Exercise - 6(B) | Q 8 | Page 132

Describe the energy flow in an ecosystem.

Exercise - 6(B) | Q 9 | Page 132

State the law which governs the energy flow in an ecosystem.

Exercise - 6(B) | Q 10 | Page 132

Show that the energy flow in an ecosystem is linear.

Exercise - 6(B) | Q 11 | Page 132

Draw a simple diagram showing the energy flow in a food chain.

Exercise - 6(B) | Q 12 | Page 132

Draw a diagram to show that the energy flow in an ecosystem is governed by the law of conservation of energy.

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(B) [Page 132]

Exercise - 6(B) | Q 1 | Page 132

Food chain begins with

• Respiration

• Photosynthesis

• Decomposition

• Decay

Exercise - 6(B) | Q 2 | Page 132

The source of energy in an ecosystem is

• Sun

•  Decayed bodies

• Green plants

• Sugar

Exercise - 6(B) | Q 3 | Page 132

Energy enters in a food chain through

• Primary consumers

• Secondary consumers

• Tertiary consumers

• Producers

Exercise - 6(B) | Q 4 | Page 132

The place of human being in food chain in an ecosystem is as

• Producer

• Consumer

• Decomposer

• Both (a) and (b)

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(C) [Page 141]

Exercise - 6(C) | Q 1 | Page 141

State two characteristics which a source of energy must have.

Exercise - 6(C) | Q 2 | Page 141

Name the two groups in which various sources of energy are classified. State on what basis are they classified.

Exercise - 6(C) | Q 3 | Page 141

What is meant by the renewable and non-­renewable sources of energy? State two differences between them, giving two examples of each

Exercise - 6(C) | Q 4 | Page 141

Select the renewable and non-renewable sources of energy from the following :

1. Coal
2. Wood
3. Water
4. Diesel
5. Wind
6. Oil
Exercise - 6(C) | Q 5 | Page 141

Why is the use of wood as a fuel not advisable although wood is a renewable source of energy?

Exercise - 6(C) | Q 6 | Page 141

Name five renewable and three non-renewable sources of energy.

Exercise - 6(C) | Q 7.1 | Page 141

What is tidal energy ?  Explain in brief.

Exercise - 6(C) | Q 7.2 | Page 141

What is ocean energy ? Explain in brief.

Exercise - 6(C) | Q 7.3 | Page 141

What is geo thermal energy ? Explain in brief.

Exercise - 6(C) | Q 8 | Page 141

What is the main source of energy for Earth?

Exercise - 6(C) | Q 9 | Page 141

What is solar energy? How is the solar energy used to generate electricity in a solar power Plant?

Exercise - 6(C) | Q 10 | Page 141

What is a solar cell? State two uses of solar cells. State whether a solar cell produces a.c. or dc. Give one disadvantage of using a solar cell.

Exercise - 6(C) | Q 11 | Page 141

State two advantages and two limitations of producing electricity from solar energy.

Exercise - 6(C) | Q 12 | Page 141

What is wind energy? How is wind energy used to produce electricity? How much electric power is generated in India using the wind energy?

Exercise - 6(C) | Q 13 | Page 141

State two advantages and two limitations of using wind energy for generating electricity.

Exercise - 6(C) | Q 14 | Page 141

What is hydro energy? Explain the principle of generating electricity from hydro energy. How much hydro electric power is generated in India?

Exercise - 6(C) | Q 15 | Page 141

Exercise - 6(C) | Q 16 | Page 141

What is nuclear energy? Name the process used for producing electricity using the nuclear energy.

Exercise - 6(C) | Q 17 | Page 141

What percentage of total electrical power generated in India is obtained from nuclear power plants? Name two places in India where electricity is generated from nuclear power plants.

Exercise - 6(C) | Q 18 | Page 141

State two advantages and two disadvantages of using nuclear energy for producing electricity.

Exercise - 6(C) | Q 19.1 | Page 141

State the energy transformation in the following:

electricity is obtained from solar energy.

Exercise - 6(C) | Q 19.2 | Page 141

State the energy transformation in the following:

electricity is obtained from wind energy.

Exercise - 6(C) | Q 19.3 | Page 141

State the energy transformation in the following:

electricity is obtained from hydro energy.

Exercise - 6(C) | Q 19.4 | Page 141

State the energy transformation in the following:

electricity is obtained from nuclear energy.

Exercise - 6(C) | Q 20 | Page 141

State four ways for the judicious use of energy.

Exercise - 6(C) | Q 21 | Page 141

What do you mean by degradation of energy? Explain it by taking two examples of your daily life.

Exercise - 6(C) | Q 22 | Page 141

The conversion of part of energy into a unuseful form of energy is called ___________

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(C) [Page 141]

Exercise - 6(C) | Q 1 | Page 141

The ultimate source of energy is :

• wood

• wind

• water

• sun

Exercise - 6(C) | Q 2 | Page 141

Renewable source of energy is :

• coal

• fossil fuels

• natural gas

• sun

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(D) [Pages 145 - 146]

Exercise - 6(D) | Q 1 | Page 145

What do you mean by greenhouse effect?

Exercise - 6(D) | Q 2 | Page 145

Name three green house gases.

Exercise - 6(D) | Q 3 | Page 145

Which of the following solar radiations pass through the atmosphere of Earth: X -rays, ultraviolet rays, visible light rays or infrared radiation?

Exercise - 6(D) | Q 4 | Page 145

What results in the increase of carbon dioxide contents of earth's atmosphere?

Exercise - 6(D) | Q 5 | Page 146

Name the radiations which are absorbed by the green house gases.

Exercise - 6(D) | Q 6 | Page 146

What would have been the temperature of earth's atmosphere in absence of green house gases in it?

Exercise - 6(D) | Q 7 | Page 146

State the effect of green house gases on the temperature of earth's atmosphere.

Exercise - 6(D) | Q 8 | Page 146

What do you mean by global warming?

Exercise - 6(D) | Q 9 | Page 146

What causes the rise in atmospheric temperature?

Exercise - 6(D) | Q 10 | Page 146

State the cause of increase of green house effect.

Exercise - 6(D) | Q 11 | Page 146

What will be the effect of global warming at the poles?

Exercise - 6(D) | Q 12 | Page 146

State the effect of global warming in coastal regions.

Exercise - 6(D) | Q 13 | Page 146

How will global warming affect the sea level?

Exercise - 6(D) | Q 14 | Page 146

How will global warming affect the agriculture?

Exercise - 6(D) | Q 15 | Page 146

State two ways to minimize the impact of global warming.

Exercise - 6(D) | Q 16 | Page 146

What is carbon tax? Who will pay it?

#### Selina solutions for Class 9 Physics Chapter 6 Exercise Exercise - 6(D) [Page 146]

Exercise - 6(D) | Q 1 | Page 146

The green house gas is :

• Oxygen

• Nitrogen

• Chlorine

• Carbon dioxide

Exercise - 6(D) | Q 2 | Page 146

The increase of carbon dioxide gas in atmosphere will cause

• Decrease in temperature

• Increase in temperature

• No change in temperature

• increase in humidity.

Exercise - 6(D) | Q 3 | Page 146

Without green house effect, the average temperature of Earth's surface would have been :

• -18°C

• 33°C

• 0°C

• 15°C

Exercise - 6(D) | Q 4 | Page 146

The global warming has resulted in :

• the increase in yield of crops

• the decrease in sea levels

• the decrease in human deaths

• the increase in sea levels

## Chapter 6: Heat and Energy

Exercise - 6(A)Exercise - 6(B)Exercise - 6(C)Exercise - 6(D)

## Selina solutions for Class 9 Physics chapter 6 - Heat and Energy

Selina solutions for Class 9 Physics chapter 6 (Heat and Energy) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Selina ICSE Concise Physics for Class 9 solutions in a manner that help students grasp basic concepts better and faster.

Further, we at Shaalaa.com provide such solutions so that students can prepare for written exams. Selina textbook solutions can be a core help for self-study and acts as a perfect self-help guidance for students.

Concepts covered in Class 9 Physics chapter 6 Heat and Energy are Concepts of Heat and Temperature, Anomalous Expansion of Water, Graphs Showing Variation of Volume and Density of Water with Temperature in the 0 to 10°C Range, Energy Flow and Its Importance, Energy Sources, Renewable Versus Non-renewable Sources, Renewable Energy, Non-renewable Energy, Use of Hydro Electrical Powers for Light and Tube Wells, Meaning of Global Warming, Effect of Global Warming, Green House Effect, Energy Degradation, Thermal Expansion - Volume Expansion.

Using Selina Class 9 solutions Heat and Energy exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in Selina Solutions are important questions that can be asked in the final exam. Maximum students of CISCE Class 9 prefer Selina Textbook Solutions to score more in exam.

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