NCERT Solutions for CBSE Class 8 Science

NCERT Solutions for Class 8 Science

NCERT Solutions for Class 8 Science Chapter 1 - Crop Production and Management

In the NCERT solutions for CBSE Class 8 Science Chapter 1 Crop Production and Management, you will learn the various techniques for preparing soil and sowing seeds. The key concepts in this chapter also include animal husbandry and food sources from animals. Learn about the types of crops to understand how cultivation is carried out by farmers. Find ways on how to improve crops by studying with our NCERT chapter solutions.

Basic Practices of Crop Production

1. Preparation of soil

Ploughing: It is the process of breaking, loosening and turning the soil over for uprooting weeds and aerating the soil. It is done using plough, hoe or cultivator.
Harrowing: It is a method to destroy germinating weeds. It is done by using a blade harrow or spike tooth harrow.
Levelling: It involves breaking big lumps of soil and levelling it. It is done by using a wooden or iron plank.
Manuring: It is the process of adding manure to the soil.

2. Sowing

The process of scattering seeds in the soil for growing crop plants is called sowing.
Broadcasting: It is the process of manually scattering seeds in the field.
Drilling: It is the process of sowing seeds at a uniform distance by using a seed drill.
Transplantation: The process of transferring seedlings from the nursery to the main field by hand is called transplantation.

3. Adding manure and fertilisers

Manure: Dead and decaying vegetable matter, waste from farms, household waste, excreta of animals form manure.
Compost: Organic substances are decomposed by bacteria and are converted into humus.
Green Manure: Farmers grow leguminous plants such as groundnuts, soya beans and pulses in between two crops.
Crop rotation is the practice of growing different crops each season in a particular field.
Organic farming is a kind of farming in which crops are grown without using chemical fertilisers and pesticides.

4. Irrigation

The process of supplying water to crop plants in fields through canals, wells, reservoirs, tube wells etc. is known as irrigation.
Traditional methods of Irrigation: Canal irrigation, moat, Rahat system, swing basket method, dhekli, chain pump.
Modern methods of Irrigation:
Basin irrigation: The land is surrounded with embankments in the form of a basin. Basins are flooded with water.
Furrow irrigation: Small channels or furrows are created along the field length between crop rows.
Drip irrigation: Water is supplied through perforated pipes.
Sprinkle irrigation: Sprinklers or spray guns are attached to a large hosepipe at regular intervals to spray water.

5. Removal of weeds

Wild and undesirable plants which grow in crop fields and compete with crops for space, soil, nutrients, water and sunlight are called weeds.
Weeding is the process of removal of weeds.
Pulling out weeds with hands.
By digging or cutting weeds from close to the ground using trowel, harrow and hoe.
Spraying a solution of weedicides such as 2,4-D, MCPA and Butachlor.

6. Harvesting

Harvesting is the cutting and gathering of mature crops.
Threshing is the process of beating grains from stems.
Winnowing is the process of separating grains from the chaff.

7. Storage of food grains

Dried grains are stored in granaries.
Grains are also stored in gunny bags made of jute.
Government stores grains in large containers or tall cylindrical structures called silos.

Read the answers to the exercises on page 14 of your CBSE Class 8 Science NCERT textbook to find out about the difference between manure and fertilizers. Are fertilizers harmful? Read all about it with the explanations and concept insight given in the NCERT solutions. Read about Kharif crops and Rabi crops. What’s the difference between them? Get all the answers in the NCERT textbook solutions.

Revise the cropping patterns in India with our NCERT CBSE Class 8 Science textbook solutions. Learn about farming methods such as Tilling, Threshing, Weeding, and more. Understand the different agricultural practices by revising the sugarcane crop production process. Review the answers to objective-type questions by referring to the solved CBSE Online Class 8 questions from your NCERT textbook.

Sometimes, instead of fill in the blanks, you may get a set of questions in a crossword form. Learn to solve such puzzles by revising the NCERT CBSE Class 8 Science solutions at TopperLearning.

NCERT Crop Production and Management Class 8 Videos

NCERT Crop Production and Management Class 8 Revision Notes

NCERT Crop Production and Management Class 8 Most Important Questions

NCERT Crop Production and Management Class 8 MCQ

NCERT Crop Production and Management Class 8 FIB

NCERT Crop Production and Management Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Agricultural Practices

Class 8 Science- Preparation Of Soil And Sowing Of Seeds

Class 8 Science- Methods Of Irrigation

Class 8 Science- Harvesting And Post Harvesting Practices

Class 8 Science- Animal Husbandry And Food From Animals

NCERT Solutions for Class 8 Science Chapter 2 - Microorganisms: Friend or Foe

When you revise the NCERT solutions of CBSE Class 8 Science Chapter 2 Microorganisms: Friend or Foe at TopperLearning, you will come across concept insights that will tell you more about the concepts being discussed. The concept insights will also alert you about the questions that are important from the exam viewpoint. In Chapter 2, learn about yeast, bacteria, fermentation and other topics. Did you know all microorganisms are not bad? Yes, there are useful microorganisms too. Discover more about microorganisms in Chapter 2 of your CBSE Class 8 syllabus

· Organisms too small to be seen with our naked eyes are called microorganisms or microbes.

· They can only be seen using a microscope.

· Uses of Microorganisms

· Increasing soil fertility

· Cleaning the environment

· Retting of fibres

· Tanning of leather

· Production of curd, bread and alcoholic beverages

· Production of antibiotics

· Production of vaccines

· The first antibiotic pencillin was discovered by Alexander Fleming in 1929.

· Fungus Penicillium notatum produces penicillin.

· Some Important Vaccines

· Microbial diseases which can spread from an infected person to a healthy person through air, water, food, physical contact or through vectors are called communicable diseases. Examples: Tuberculosis, chickenpox.

· The insects or other animals which transmit disease causing microorganisms to humans without themselves getting infected are called carriers. Examples: Housefly, mosquito.

Nitrogen Fixation

· The process of converting nitrogen gas of the atmosphere into compounds of nitrogen which can be used by plants is called nitrogen fixation.

· By nitrogen-fixing bacteria: Ammonia is converted to nitrates by nitrifying bacteria.

· By Rhizobium bacteria: Rhizobia live in the root nodules of leguminous plants. They convert free nitrogen from the atmosphere into soluble nitrates.

· By blue-green algae: They fix nitrogen gas into ammonia, nitrates and nitrites.

· By lightening: During lightning, nitrogen and oxygen from the atmosphere combine to form nitrogen oxides which react with rainwater and form dilute nitric acid.

· Nitric acid reacts with the minerals present in the soil and forms nitrate.

· The process of circulation of nitrogen between the atmosphere, soil, plants and animals is called the nitrogen cycle.

Class 8 Science Chapter 2 will assist you to understand the different types of microorganisms. Study in detail about microorganisms such as fungi, algae, protozoa and bacteria. Find out which microorganisms are good and which microorganisms are considered harmful. Also, know the various methods for preserving food.

Houseflies are common carriers of communicable diseases. Understand more about communicable diseases with the NCERT solutions for CBSE Class 8 Science. Learn all about the harm that can be caused by the bad microorganisms and how to prevent them with help of good microorganisms. Additionally, in the chapter solutions, understand how antibiotics help to protect you against bad microorganisms.

NCERT Micro Organisms Class 8 Videos

NCERT Micro Organisms Class 8 Revision Notes

NCERT Micro Organisms Class 8 Most Important Questions

NCERT Micro Organisms Class 8 MCQ

NCERT Micro Organisms Class 8 FIB

NCERT Micro Organisms Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Friendly Micro Organisms

Class 8 Science- Harmful Microorganisms

Class 8 Science- More On Harmful Microorganisms

Class 8 Science- Food Preservation

Class 8 Science- Nitrogen Cycle

NCERT Solutions for Class 8 Science Chapter 3 - Coal and Petroleum

With our NCERT solutions for CBSE Class 8 Science Chapter 3 Coal and Petroleum, get descriptions on how coal tar, coal gas and coke are produced from coal. This chapter also covers the limited availability of natural resources and the need for the careful usage of resources for a sustainable future.

What is Bitumen? How does it help us? Find answers in the NCERT solutions Science free textbook solutions. Understand the key benefits of Liquefied Petroleum Gas or LPG and Compressed Natural Gas or CNG. Get the answers to true or false type questions in your textbook too. Our solutions are loaded with concept insights to make it easy for you to understand the concepts.

Natural resources can be classified into two types:

· Inexhaustible Natural Resources: The resources which are present in unlimited quantity in nature and are not likely to be exhausted by human activities are called inexhaustible natural resources.

Examples: Sunlight, air

· Exhaustible Natural Resources: The resources which are present in a limited quantity in nature and can be exhausted by human activities are called exhaustible natural resources.

Examples: Forests, wildlife, minerals, coal, petroleum

Fossil fuels: The natural fuels formed from the remains of living organisms buried under the Earth long, long ago are called fossil fuels.

· Coal is a hard, black, combustible mineral which consists mainly of carbon.

· It is found in deep coal mines under the surface of the Earth.

· On heating, coal, which is mainly carbon, produces carbon dioxide gas and a lot of heat energy.

C + O₂ → ® CO_² + Heat

· Products of Coal

i. Coke

ii. Coal Tar

iii. Coal Gas

· Petroleum

· It is a dark-coloured, thick crude oil found deep below the ground in certain areas.

· Petroleum means rock oil (petra = rock, oleum = oil).

· Just like coal, petroleum is also a fossil fuel.

· Constituents of Petroleum and their Uses

Constituents of Petroleum	Uses
Liquid Petroleum Gas	Fuel for home and industry
Petrol	Motor and aviation fuel, solvent for dry cleaning
Kerosene	Fuel for stoves, lamps and jet aircraft
Diesel	Fuel for heavy motor vehicles, electric generators
Lubricating oil	Lubrication
Paraffin wax	Making ointments, candles, Vaseline
Bitumen	In paints and road surfacing

· Natural Gas

· Natural gas mainly consists of methane with small quantities of ethane and propane.

· When natural gas is compressed by applying pressure, it is called compressed natural gas (CNG).

· It is a very important fossil fuel because it is easy to transport through pipes.

· It is a clean fuel.

Read our NCERT Class 8 Science solutions to understand the preparation method of Kerosene. In addition, the solutions give you accurate explanations of topics like fossil fuels, petroleum and coke. With the availability of the solutions online 24x7, you can revise the chapter at any time as per your learning plan. To understand what kinds of questions were asked in the questions recently, check the CBSE Class 8 sample paper 2020-21.

NCERT Coal and Petroleum Class 8 Videos

NCERT Coal and Petroleum Class 8 Revision Notes

NCERT Coal and Petroleum Class 8 Most Important Questions

NCERT Coal and Petroleum Class 8 MCQ

NCERT Coal and Petroleum Class 8 FIB

NCERT Coal and Petroleum Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Coal And Petroleum

Class 8 Science- Petroleum And Natural Gas

NCERT Solutions for Class 8 Science Chapter 4 - Combustion and Flame

In the NCERT solutions for CBSE Class 8 Science Chapter 4 Combustion and Flame, study combustible and non-combustible gases. Find out why goldsmiths use the outermost part of the flame to melt gold and silver. Discover the meaning of terms such as flame, combustion, fuels, fire and burning. Revise the various types of combustion with our CBSE Online Class 8 solutions.

Revisit the lessons on the process of combustion in this chapter. Understand what an ignition temperature is. Grasp the difference between wood and LPG. Through the CBSE Class 8 Science sample paper and NCERT solutions, brush up your understanding of heat generated in a burning candle. Revise the calorific value of a fuel.

A chemical process in which a substance reacts with the oxygen of the air to give heat and light is called combustion.

Magnesium + Oxygen $begin mathsize 12px style rightwards arrow with Combustion on top end style$ Magnesium oxide + Heat + Ligh

Types of Combustion

Rapid Combustion: The reaction in which a large amount of heat and light are produced in a short period of time

Spontaneous Combustion: The reaction which occurs on its own

Explosive Combustion: A very fast combustion in which a large amount of heat, light and sound are produced is called explosive combustion.

· Flame and Structure of Flame

A flame is a region where the combustion or burning of gaseous substances takes place along with the evolution of heat and light.

Different zones of candle flame

Inner zone

· This is the dark zone which lies around the wick of the candle. It is the innermost zone of the flame.

Luminous middle zone

· The middle zone is the brightest zone of flame. In this zone, there is an inadequate supply of air.

Non-luminous zone

· The outermost zone of the flame is called the zone of complete combustion.

· This is the hottest zone of the flame.

Blue zone

· At the bottom of the flame lies a blue zone.

Fuels

· The material which is burnt to produce heat is called a fuel.

Examples: Wood, coal, LPG, kerosene, petrol, diesel, natural gas and biogas are some common fuels.

· There are three types of fuels:

o. Solid fuels

o. Liquid fuels

o. Gaseous fuels

Fuel Efficiency

· Different fuels produce different amounts of heat on burning.

· The amount of heat produced by the complete burning of 1 kilogram of a fuel is called its calorific value.

· The calorific value of a fuel is expressed in the unit of kilojoules per kilogram.

The CBSE syllabus for Class 8 Science becomes more and more interesting in this chapter as it reveals the scientific facts about things that leave you in awe. For example, find out why dry leaves are used to create fire instead of green leaves.

NCERT Combustion and Flame Class 8 Videos

NCERT Combustion and Flame Class 8 Revision Notes

NCERT Combustion and Flame Class 8 Most Important Questions

NCERT Combustion and Flame Class 8 MCQ

NCERT Combustion and Flame Class 8 FIB

NCERT Combustion and Flame Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Combustion

Class 8 Science- Flame

Class 8 Science- Fuels

Class 8 Science- How Do We Control Fire?

Class 8 Science- Burning And Its Problems

NCERT Solutions for Class 8 Science Chapter 5 - Conservation of Plants and Animals

Through the NCERT solutions for CBSE Class 8 Science Chapter 5 Conservation of Plants and Animals, revise the concepts of deforestation and reforestation. Find answers on what are the differences between a zoo, a biosphere reserve and a wildlife sanctuary. Also, get answers on concepts such as flora, fauna, endangered species and extinct species.

· Deforestation is cutting down of trees or destroying forests to use the land for some other purpose.

· Reforestation is restocking of destroyed forests by planting new trees.

· A species is an organism of a particular kind whose members can interbreed among themselves to produce fertile young ones

· Rare species exist in relatively low numbers but are not necessarily in immediate danger of extinction. Examples: Black and white ruffed lemur, Aloe polyphylla.

· An endangered species is one in which the population of organisms is at the risk of extinction. Examples: The Indian rhinoceros, the Great Indian bustard, Pink Butterfly Orchid.

· Species which exist in low numbers and may become endangered due to destruction of their habitat, overexploitation or due to some other environmental factor are called vulnerable species. Examples: The Asian elephant, Rafflesia.

· Threatened species are any species which are vulnerable to endangerment in the near future. Examples: Giant Panda, Monarch butterfly.

· Plant and animal species which are found only in a particular region and nowhere else in the world are called endemic species. Examples: Nilgiri leaf monkeys found in the Nilgiri Hills of the Western Ghats.

· A species is considered extinct when no member of the species is still alive. Examples: Dodo, Woolly Mammoth.

· Biosphere reserves or biodiversity zones are large areas of protected land for the conservation of wildlife, plant and animal resources and the traditional life of tribal people living in the area.

· Plants naturally occurring in a particular area constitute the flora. Teak, Jamun, Fern, Mango and Arjun constitute the flora of Pachmarhi Biosphere Reserve.

· Animals naturally occurring in a particular area constitute its fauna. Cheetah, Wolf, Leopard, Chinkara, Blue bull, Barking deer and Wild dog constitute the fauna of Pachmarhi Biosphere Reserve.

· A zoo is a place where wild animals and birds live in artificial habitats such as cages and enclosures.

· A wildlife sanctuary is an area where animals are protected from any kind of disturbance such as hunting, predation and competition.

· National parks comprise a large area of land owned by the government which is restricted from development and is protected for its landscape, flora, fauna and ecosystem on the whole.

NATIONAL PARK	STATE	NATIONAL PARK	STATE
Corbett National Park	Uttarakhand	Sunderbans National Park	West Bengal
Kanha National Park	Madhya Pradesh	Bandipur National Park	Karnataka
Ranthambore National Park	Rajasthan	Dachigam National Park	Jammu and Kashmir
Gir National Park	Gujarat	Sariska National Park	Rajasthan
Kaziranga National Park	Assam	Satpura National Park	Madhya Pradesh

· Red Data Book keeps a record of all the endangered animals and plants.

· The movement of animals in large numbers from one place to another to overcome unfavourable conditions is called migration. Siberian cranes migrate to Bharatpur in Rajasthan because the environmental conditions there are more favourable as compared to Siberia, the place where they actually come from.

· Paper recycling is the process of remaking new paper products from waste paper.

Revise the NCERT CBSE Class 5 Science solutions by qualified teachers with huge experience in the field of education. These reputed teachers guide you with answers on Biosphere reserves, wildlife sanctuaries, zoos, and more. The chapter tells you about the types of species and why certain species fall under the extinct category.

Also, understand the terms flora and fauna with the examples given by our subject experts. The CBSE syllabus for Class 8 Science Chapter 7 also covers important details on global warming, green wealth, deforestation, ecological balance, and more. In this Science chapter, understand the significance of the conservation of forests and how animal poaching impacts forests. Explore CBSE Class 8 Science sample papers to practise different types of questions from this chapter.

NCERT Conservation of Plants and Animals Class 8 Videos

NCERT Conservation of Plants and Animals Class 8 Revision Notes

NCERT Conservation of Plants and Animals Class 8 Most Important Questions

NCERT Conservation of Plants and Animals Class 8 MCQ

NCERT Conservation of Plants and Animals Class 8 FIB

NCERT Conservation of Plants and Animals Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Deforestation And Its Causes

NCERT Solutions for Class 8 Science Chapter 6 - Reproduction in Animals

Use our Class 8 Science Chapter 6 Reproduction in Animals solutions to understand the difference between a zygote and a foetus. This chapter will take you through the process of human reproduction and fertilisation. Also, find out how living organisms produce offspring. Learn about sexual and asexual reproduction.

Looking for answers to NCERT CBSE Class 8 Science textbook questions on page 110? We’ve got answers for all 9 questions on the page by some of the highly experienced teachers in India. Understand the various types of fertilization with well-prepared solutions.

In the Science exam, you will be asked different kinds of questions that are covered in your NCERT textbook. These include crossword questions, true or false questions and more. So, revise the free textbook solutions as per the CBSE Class 8 syllabus to prepare for those questions. Get the required learning materials on the topic of reproduction in animals and get ready for your class tests and final exam.

NCERT Reproduction in Animals Class 8 Videos

NCERT Reproduction in Animals Class 8 Revision Notes

NCERT Reproduction in Animals Class 8 Most Important Questions

NCERT Reproduction in Animals Class 8 MCQ

NCERT Reproduction in Animals Class 8 FIB

NCERT Reproduction in Animals Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Reproduction In Humans

Class 8 Science- Fertilisation

NCERT Solutions for Class 8 Science Chapter 7 - Reaching the Age of Adolescence

NCERT solutions for CBSE Class 8 Science Chapter 7 Reaching the Age of Adolescence aims to give you answers on what are the chemical and physical changes which take place in humans when they reach the age of adolescence and puberty. It also gives students insight into the topics of hormones and reproduction that are covered in this chapter.

Different phases in the life of human beings bring about a certain change in their physical characteristics. Adolescence is a time when humans are transitioning to adulthood. Learn everything about this phase in the CBSE Class 8 Science Chapter Reaching the Age of Adolescence. Understand what happens when boys and girls reach the stage of reproductive maturity.

The chapter educated you about important concepts such as puberty and mensuration. Revise the lessons on the human endocrine system with the NCERT CBSE Class 8 Science textbook solutions. The chapter also informs you of the role of sex hormones in the human body. Also, understand how adolescence results in the development of sexual characters in boys and girls.

NCERT Reaching the Age of Adolescence Class 8 Videos

NCERT Reaching the Age of Adolescence Class 8 Revision Notes

NCERT Reaching the Age of Adolescence Class 8 Most Important Questions

NCERT Reaching the Age of Adolescence Class 8 MCQ

NCERT Reaching the Age of Adolescence Class 8 FIB

NCERT Reaching the Age of Adolescence Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Adolescence And Puberty

Class 8 Science- Emotional Changes In Adolescents

Class 8 Science- Hormones

Class 8 Science- Hormones And Reproduction

NCERT Solutions for Class 8 Science Chapter 8 - Force and Pressure

Does force have a direction? How is the knowledge of force applied in real life? Understand the answers with TopperLearning’s NCERT solutions for CBSE Class 8 Science. The study resources like CBSE Class 8 sample paper 2020-21 that you find at our e-learning portal are reliable as these are prepared by some of the best teachers around. You can access and revise these textbook solutions at your convenience by visiting our study portal.

Force

· Force is a push or a pull on an object.

· It changes or tends to change the state of rest or the state of motion of an object by a push or pull.

· The SI unit of force is Newton.

Effects of Force

· A force can change the state of motion of an object.

· A force can change the shape and size of the object.

Types of Forces

Contact Forces

· A force which can cause or change the motion of an object by physical touching is called a contact force.

Types of Contact Forces

1. Muscular Force

· The force caused by the action of muscles is called muscular force.

2. Friction

· The force responsible for changing the state of motion of an object is called friction. Non-contact Forces

· These forces act at a distance without any physical contact.

Types of Non-contact Forces

1. Magnetic Force

· The force exerted by a magnet is known as magnetic force.

2. Electrostatic Force

· The force exerted by a charged body on another charged or uncharged body is known as electrostatic force.

3. Gravitational Force

· The attraction of objects towards the Earth is known as force of gravity or gravity.

· This force acts on all objects in the Universe.

Pressure

· Pressure is the force per unit area applied in a direction perpendicular to the surface of an object.

· It is given as

$begin mathsize 12px style Pressure equals Force over Area end style$

· The unit of pressure is Newton/metre² (N/m² or Nm⁻²), which is equal to 1 Pascal (Pa).

· A liquid exerts pressure on the base of the container (vessel) because of its weight.

In the NCERT solutions for CBSE Class 8 Science Chapter 8 Force and Pressure, get answers on how the force works and understand what is contact force and non-contact force. Revise the concepts like atmospheric pressure, electrostatic force, gravitational force, muscular force etc. that are covered in your NCERT Science book CBSE Class 8 syllabus.

Study your CBSE Class 8 Science lessons on gravity and friction in this chapter. The NCERT book covers several questions on force and friction. Understand these concepts with examples and concept insights presented by subject experts in our NCERT solutions. This chapter will educate you about the different types of force such as muscular force, electrical force and so on.

NCERT Force and Pressure Class 8 Videos

NCERT Force and Pressure Class 8 Revision Notes

NCERT Force and Pressure Class 8 Most Important Questions

NCERT Force and Pressure Class 8 MCQ

NCERT Force and Pressure Class 8 FIB

NCERT Force and Pressure Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Force And Its Effects

Class 8 Science- Contact Forces

Class 8 Science- Non Contact Forces

Class 8 Science- Pressure

Class 8 Science- Atmospheric Pressure

NCERT Solutions for Class 8 Science Chapter 9 - Friction

NCERT solutions for CBSE Class 8 Science Chapter 9 Friction will help you to find out what affects friction and what causes friction. Find out what are the advantages and disadvantages of friction, how friction affects a moving car or aeroplane etc. Gear up your exam preparation by practising CBSE Class 8 Science sample papers and solutions.

Force of friction

· Friction is the force which develops at the surfaces of contact of two bodies and opposes their relative motion.

· It always acts in the direction opposite to the applied force.

There are three types of friction:

Static Friction

· The force required to overcome friction at the instant an object starts moving from rest is the measure of static friction.

Sliding Friction

· The force required to keep an object moving with the same speed is the measure of sliding friction.

· Sliding friction is always lesser than static friction.

Rolling Friction

· The frictional force which comes into action when an object rolls over a surface is called rolling friction.

· This force slows down the motion of a rolling object.

· Friction is a necessary evil. There are instances in daily life where friction is a necessity.

Advantages of Friction

· Construction of buildings is possible only because of friction.

· We are able to write because of the friction between the paper and the tip of a pen.

· Without friction between our shoes and the ground, we will not be able to walk.

Disadvantages of Friction

· Friction produces heat in the moving parts of machines which causes wear and tear of the parts.

· A lot of energy is wasted in overcoming friction.

· It causes the wear and tear of the soles of the shoes.

Increase and Decrease in Friction

· Ways to increase friction:

o. Providing grooves to shoes and grips to balls

o. Treading tyres of vehicles

o. Threading screws

o. Using brake pads in the brake system of bicycles and automobiles

· Ways to decrease friction:

o. By lubricants (i.e., grease, oil and graphite)

o. By polishing surfaces

o. By using wheels

Fluid Friction

· Liquids and gases are together known as fluids.

· Substances which are able to flow easily are called fluids.

· The frictional force exerted by fluids is known as drag.

Learning topics like friction will open your eyes to amazing Science facts that explain why a book slides when it is kept on a titled writing desk. This chapter will tell you why sports shoes have spikes and why tyres wear out after a certain time. Read our NCERT solutions for Class 8 and relearn the concept of frictional force.

Understand how friction makes a wet floor slippery by referring to our CBSE Online Class 8 Science NCERT answers. Skim through the various examples of how friction is an important concept of Science that impacts our daily life. With examples in our CBSE class 8th science ncert solutions

you will be able to think of ideas where the concept of friction applies and your conceptual knowledge will improve. This, in turn, will allow you to write about the topic correctly in your exam and will enable you to improve your exam scores too.

NCERT Friction Class 8 Videos

NCERT Friction Class 8 Revision Notes

NCERT Friction Class 8 Most Important Questions

NCERT Friction Class 8 MCQ

NCERT Friction Class 8 FIB

NCERT Friction Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Friction: What Is It?

Class 8 Science- Friction Importance And Methods To Reduce It

Class 8 Science- Friction: Necessary Evil?

NCERT Solutions for Class 8 Science Chapter 10 - Sound

Understand the various types of sounds and how sound is produced with the help of NCERT solutions for CBSE Class 8 Science Chapter 10 Sound. Learn what kind of sound is considered noise. Also, study sound vibration and sound frequency.

· Sound is a form of energy which produces the sensation of hearing in our ears.

Sound Produced by a Vibrating Body

· The rapid to-and-fro or back-and-forth motion of an object is called vibration.

· A vibrating object produces sound.

Sound Produced by Humans

· In humans, the sound is produced by the voice box or the larynx.

· The vocal cords are about 20 mm long in men, 15 mm long in women (5 mm shorter) and they are very short in children.

Propagation of sound

· Sound needs a material medium to travel.

· It cannot travel through vacuum.

Human Ear

· We hear sound with our ears.

· When sound enters the ear, it travels down a canal which has a thin stretched membrane at its end. It is called the eardrum.

· The ear drum sends the vibrations to the inner ear and the signals are then carried to the brain.

Characteristics of Sound

· The to-and-fro motion of a vibrating object is called oscillatory motion.

· The number of oscillations per second is called the frequency of oscillation. It is expressed in hertz (Hz).

· The time taken by the vibrating particle for one full vibration or oscillation is called the time period of oscillation.

· The properties by which sounds can be differentiated are amplitude and frequency.

Loudness

· The loudness of sound is proportional to the square of the amplitude.

· The loudness of sound is measured in decibel (dB).

· If loudness exceeds 80 dB, then the sound becomes physically painful.

Find accurate NCERT solutions for CBSE Class 8 Chapter Sound at TopperLearning. In this chapter, you will some of the basic concepts related to the study of sound. You will get to understand whether sound travels through solids and liquids. Find out how frequency is related to the pitch of an adult person’s voice and how it compares to a baby’s voice.

Is there a limit to the frequency of sound humans can hear clearly? Are there sounds that are inaudible to human ears? Know about the listening power of humans with Science facts on sound in our CBSE Class 8 Notes for revision with NCERT textbook exercises. Besides, revise the application of the frequency formula and other formulas from this chapter with our step-wise answers.

NCERT Sound Class 8 Videos

NCERT Sound Class 8 Revision Notes

NCERT Sound Class 8 Most Important Questions

NCERT Sound Class 8 MCQ

NCERT Sound Class 8 FIB

NCERT Sound Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Sound: How Is It Produced?

Class 8 Science- Sound: How Is It Propagated?

Class 8 Science- Sound Wave: Characteristics

Class 8 Science- Noise And Music

NCERT Solutions for Class 8 Science Chapter 11 - Chemical Effects of Electric Current

In our NCERT CBSE Class 8 Science textbook solutions Chapter 11 Chemical Effects of Electric Current, Science experts provide answers on what happens when electric current flows through a chemical solution or water. Also, understand the concept of electroplating while learning about the chemical effects of current by referring to our NCERT solutions for Class 8 Science Chapter 11.

This chapter includes

Conductors

· Substances which allow electricity to pass through them are called conductors.

Insulators

· Substances which do not allow electric current to pass through them are called insulators.

· Examples: Plastic, rubber, wood

Conduction of Electricity through Liquid

· Liquids which conduct electricity are solutions of acids, bases and salts in water.

Difference in Conduction by Solids and Liquids

Differences in Conduction by Solids

Differences in Conduction by Liquids

Electricity is carried by electrons.

Electricity is carried by positively and negatively charged ions.

No chemical change takes place.

Chemical change takes place.

To Test whether Liquids Conduct Electricity

· The conduction of electricity through a liquid can be tested by a conduction tester.

· A conduction tester is a device used to determine whether a substance is a good or poor conductor of electricity.

Chemical Effects of Electric Current

· When an electric current is passed through a conducting solution, some chemical reaction occurs.

Electroplating

· Electroplating is an application of the chemical effect of electric current.

Process of Electroplating

· In the process of electroplating, a metal salt solution is taken in a container.

· The metal to be coated is dipped in the solution and connected to the negative pole.

· The metal for desired coating is connected to the positive pole.

· When an electric current is passed through the solution, the metal from the anode is dissolved in the salt solution and deposited over the cathode.

· Thus, a coating of the desired metal is obtained on another metal.

Revise this important chapter with TopperLearning’s CBSE Class 8 Science NCERT solutions. Understand what is electroplating corrosion and how it impacts metal objects. Along with our solutions, there are these concept insights that give you complete clarity of the concepts covered in the textbook solutions.

List Of Sub Chapters

Learn why water is a good conductor of electricity and why it is difficult to repair an electrical appliance when it is raining. Our NCERT solutions for Class 8 Science will help you grasp the right answers to important questions concerning real-life applications. With a thorough revision of these chapter concepts, exam questions on the chemical effects of electric current will be comfortable to tackle. To practise questions for the exam, check CBSE Class 8 Science sample papers and solutions.

NCERT Chemical Effects of Electric Current Class 8 Videos

NCERT Chemical Effects of Electric Current Class 8 Revision Notes

NCERT Chemical Effects of Electric Current Class 8 Most Important Questions

NCERT Chemical Effects of Electric Current Class 8 MCQ

NCERT Chemical Effects of Electric Current Class 8 FIB

NCERT Chemical Effects of Electric Current Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Conductors Of Electricity: Liquids

Class 8 Science- Chemical Effects Of Electric Current

NCERT Solutions for Class 8 Science Chapter 12 - Some Natural Phenomena

While revising the NCERT solutions for CBSE Class 8 Science Chapter 12 Some Natural Phenomena, you will find out more about natural phenomena such as earthquakes and lightning. Also, study the concept of charge, positive charge, negative charge, electric discharge, the principle of lightning conductor etc.

Natural phenomena which cause damage to human life and property can be harmful and destructive.

Lightning

· Lightning is caused by accumulation of charges in the clouds.

Occurrence of Lightning

· The formation of clouds involves friction between the water particles in the atmosphere.

· This friction charges the particles.

· The creation of charges tends to make a path towards the ground which results in a narrow streak of electrical discharge which is called lightning.

Types of Changes and their Interaction

· Like charges repel and unlike charges attract each other.

Like charges repel

Unlike charges attract

· An electroscope detects the type of charge on a body.

Lightning Safety

· Lightning is caused by the heavy electric discharge from the clouds to the Earth.

· If lightning is not controlled, it can cause heavy damage to life and property.

Earthquakes

· An earthquake is a natural phenomenon which cannot be predicted. It is a sudden shaking or trembling of the Earth which lasts for a short time.

Cause of Earthquakes

· Tremors are caused by a disturbance in the uppermost layer of the Earth called the crust.

· The Earth consists of three major layers—core, mantle and crust.

· The region where one plate slides against the other is referred to as a fault zone. This is where an earthquake occurs. Hence, such zones are referred to as seismic zones.

· The instrument which measures the severity of an earthquake is called a seismograph.

Protection against Earthquakes

· We should take necessary precautions to protect ourselves from earthquakes.

If you are at home:

· Take shelter under a table and stay there till the shaking stops.

· Stay away from tall and heavy objects which may fall on you.

· If you are in bed, then do not get up but protect your head with a pillow.

If you are outdoors:

· Find a clear place away from buildings, trees and overhead power lines.

· If you are in a car or a bus, do not come out till the tremors stop and ask the driver to drive slowly to a clear spot.

With the NCERT solutions for CBSE Class 8 Science by TopperLearning, you will learn how rubbing two objects generates an electric charge. Revise the correct answers to True or False questions with concept insights which give you the additional benefit of better conceptual clarity. When you know the concepts well, you will be able to elaborate on them in your exam with ease.

NCERT solutions for your CBSE Class 8 Science textbook questions not only equips you for your school exam but also improve your general knowledge. As you feel more confident to provide a clear explanation for natural phenomena, you become more confident to participate in Science-based competitions at the school level. The CBSE Class 8 syllabus concepts will also make various advanced concepts in higher classes simpler for you as you move ahead in your academic journey.

NCERT Some Natural Phenomena Class 8 Videos

NCERT Some Natural Phenomena Class 8 Revision Notes

NCERT Some Natural Phenomena Class 8 Most Important Questions

NCERT Some Natural Phenomena Class 8 MCQ

NCERT Some Natural Phenomena Class 8 FIB

NCERT Some Natural Phenomena Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Natural Phenomena: Lightning And Earthquakes

Class 8 Science- Charges And Their Interaction

NCERT Solutions for Class 8 Science Chapter 13 - Light

NCERT solutions for CBSE Class 8 Science Chapter 13 Light helps you understand the concept of human vision and visual impairment. In this chapter, you will be introduced to the structure of the eye. Also, learn about the dispersion of light and the laws of reflection.

· Light is a form of energy.

· It helps us see different colourful objects around us.

Reflection

· It is the process where the incident light on an object bounces back into the same medium.

Laws of Reflection

· The angle of incidence is equal to the angle of reflection.

· The incident ray, the reflected ray and the corresponding normal all lie in a plane.

Lateral Inversion

· Lateral inversion is the effect produced by a plane mirror in reversing images from left to right, i.e., the right part of an object appears to the left in its image, and the left part of the object appears to the right.

Regular and Diffused Reflection

· If the reflected rays from a surface are parallel, then the reflection is termed regular reflection.

· If the surface is not a plane surface, then the reflected rays are not parallel to each other and the reflection is called diffused reflection or irregular reflection.

Multiple Reflection

· If a reflected light ray is reflected again on being incident on another surface, it is termed multiple reflection.

Sunlight–White or Coloured

· The phenomenon of splitting of a beam of white light into its constituent colours on passing through a prism is called the dispersion of light.

In school, you will learn more about light as you progress through classes. In the solutions for CBSE Class 8 Science NCERT book, you will get familiar with the basic concepts part of the study of light. Revise about different types of reflection – diffused reflection and regular reflection. The chapter solutions will benefit you immensely during your revision of critical chapter concepts for the exam.

Revisit the important topic of laws of reflection with TopperLearning’s NCERT solutions for CBSE Class 8 Science. Relearn the relationship between the angle of incidence and angle of reflection. The chapter is intriguing with solutions on how to construct a kaleidoscope to answers on how to take care of eyes.

NCERT Light Class 8 Videos

NCERT Light Class 8 Revision Notes

NCERT Light Class 8 Most Important Questions

NCERT Light Class 8 MCQ

NCERT Light Class 8 FIB

NCERT Light Class 8 Short Answer Questions

List Of Sub Chapters

Class 8 Science- Reflected Light

Class 8 Science- Laws Of Reflection

Class 8 Science- How Do Our Eyes See?

Class 8 Science- Visual Impairment