CBSE Class 8

Conservation of Plants and Animals Class 8 Extra Questions and Answers Science Chapter 7 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 7 Extra Questions and Answers Conservation of Plants and Animals

Extra Questions for Class 8 Science Chapter 7 Conservation of Plants and Animals with Answers

Conservation of Plants and Animals Class 8 Extra Questions Very Short Answer Type

Question 1.
Name a sanctuary of India.
Answer:
Bharatpur bird sanctuary.

Question 2.
Name a national park of India.
Answer:
Kaziranga National Park.

Question 3.
Name a wildlife sanctuary of India.
Answer:
Lockchao wildlife sanctuary.

Question 4.
Name a biosphere reserve of India,
Answer:
Great Nicobar Biosphere Reserve.

Question 5.
What causes drought?
Answer:
Reduced rainfall causes drought.

Question 6.
Name the areas meant for I conservation of biodiversity.
Answer:
Biosphere reserve.

Question 7.
Name two wildlife sanctuaries of Panchmarhi biosphere reserve.
Answer:
Bori and Panchmarhi.

Question 8.
Give two examples each of flora and fauna.
Answer:
Examples of flora: Mango, Jamun. Examples of fauna: Chinkara, cheetah

Question 9.
Name one endemic animal.
Answer:
Indian giant squirrel is an endemic animal.

Question 10.
Name two endemic flora of Panchmarhi.
Answer:
Sal and wild mango are two endemic, flora of Panchmarhi.

Question 11.
Apart from wildlife sanctuaries, name one place where animals are protected?
Answer:
Zoo.

Question 12.
Name the first reserve forest of India.
Answer:
Satpura.

Question 13.
What is special about the forest of Satpura?
Answer:
The finest teak of India is found in this forest.

Question 14.
Do the tribals still live in forest?
Answer:
Yes, many tribals still live in forests.

Question 15.
Name one animal which has become completely extinct?
Answer:
Dinosaur.

Question 16.
Define biosphere.
Answer:
Biosphere is that part of earth in which living organisms exist or which support life.

Question 17.
What is biodiversity?
Answer:
Biodiversity is the variety of plants, animals and microorganisms generally found in an area.

Conservation of Plants and Animals Class 8 Extra Questions Short Answer Type 1

Question 1.
Name two natural causes of deforestation.
Answer:
Two natural causes of deforestation are:

1. forest fire, and
2. severe drought.

Question 2.
Define endemic species.
Answer:
The species that are exclusively found in a particular area only and not naturally found anywhere else are known as endemic species.

Question 3.
What do you mean by species?
Answer:
Species is a group of population which are capable of interbreeding with each other.

Question 4.
State some examples of fauna, endemic to Panchmarhi Biosphere Reserve.
Answer:
Bison, Indian giant squirrel and flying squirrel are some of the fauna endemic to the Panchmarhi Biosphere Reserve.

Question 5.
What, does a sanctuary provide?
Answer:
It provides protection and suitable living conditions to wild animals.

Question 6.
Why are even protected forests not safe?
Answer:
Even protected forests are not safe because poachers encroach and destroy them.

Question 7.
What is a rock shelter?
Answer:
Rock shelters are the evidences of prehistoric human life in the jungles of Satpura National Park. They were meant for human living.

Question 8.
What idea do the rock shelters give?
Answer:
The rock shelters give us an idea about the life of the prehistoric/primitive humans.

Question 9.
What do you mean by the term Project Tiger?
Answer:
“Project Tiger” is the name of a project which was launched by the government of our country to protect the tigers of the country.

Question 10.
What was the objective of Project Tiger?
Answer:
The objective of Project Tiger was to ensure the maintenance of a viable population of tigers in our country.

Question 11.
Why is Satpura Tiger Reserve a unique place?
Answer:
The Satpura Tiger Reserve is unique in the sense that a significant increase in the population of tigers has been seen here.

Question 12.
Are there different Red Data Books for plants and animals?
Answer:
Yes, there are different Red Data Books for plants, animals and other species.

Question 13.
What do you mean by reforestation?
Answer:
Reforestation means restocking of the destroyed forests by planting new trees.

Conservation of Plants and Animals Class 8 Extra Questions Short Answer Type 2

Question 1.
Define endangered animals with two examples.
Answer:
Animals whose numbers are diminishing to a level that they might face extinction are known as the endangered animals. This is because survival of some animals has become difficult because of disturbances in their natural habitat.

The example of the endangered animals are: Indian elephant, Bengal tiger, Indian lion, Indian Rhino and Gharial.

Question 2.
What are the causes and consequences of deforestation?
Answer:
Causes of deforestation :
(a) Forests are cleared for accommodating expanding urban areas and for meeting increasing demands.
(b) Forests are destroyed to clear land for crops and cattle grazing.
(c) Trees are cut down to be used for firewood.

Consequences of deforestation:

1. Soil erosion
2. Loss of biodiversity
3. Floods and droughts
4. Climate change due to global warming
5. Disruption of water cycle

Question 3.
Explain the term Biosphere Reserve. What is its importance?
Answer:
Biosphere Reserves are the areas meant for conservation of biodiversity (plants, animals and microorganisms found in an area). Biosphere Reserves help to maintain the biodiversity and culture of that area.

Question 4.
Define the term “Wildlife Sanctuaries.” Name some threatened wild animals. How a,re they protected?
Answer:
Wildlife Sanctuaries are the areas where wild animals are protected and conserved. Some of the threatened wild animals like blackbuck, white-eyed buck, elephant, golden cat, pink-headed duck, gharial, marsh crocodile, python, rhinoceros, etc, are protected and preserved in different Wildlife Sanctuaries.

Question 5.
What are found in rock shelters of Panchmarhi Biosphere Reserves?
Answer:
There are rock paintings found in the rock shelters. Figures of animals, men shown as fighting, hunting, dancing, and playing musical instruments are depicted in these rock paintings. Figures of man-eater tiger and a group of people are also shown in these rock paintings.

Conservation of Plants and Animals Class 8 Extra Questions Long Answer Type

Question 1.
Define a desertification and deforestation with two consequences of each.
Answer:
Desertification:
Excessive deforestation leads to removal of the top layer of the soil which exposes the lower, hard and rocky layers. This soil has less humus and is less fertile. Gradually the fertile land gets converted into deserts. It is called desertification. Agriculture, animal husbandry and groundwater pumping are all significant contributors to the process.

Consequences of desertification :
(a) Desertification affects the agriculture to a large extent.
(b) It results in decease in rain fall. ,
(c) Desertification exposes the land to floods.
(d) It results in decease in the level of – groundwater.

Deforestation:
Clearing of forests by cutting down forest trees over a wide area is called deforestation,
Consequences of deforestation :
(a) Soil erosion
(b) Loss of biodiversity
(c) Floods and droughts
(d) Climate change due to global warming
(e) Disruption of water cycle

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Combustion and Flame Class 8 Extra Questions and Answers Science Chapter 6 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 6 Extra Questions and Answers Combustion and Flame

Extra Questions for Class 8 Science Chapter 6 Combustion and Flame with Answers

Combustion and Flame Class 8 Extra Questions Very Short Answer Type

Question 1.
Why is food called fuel for our body?
Answer:
In our body, food is broken down by reaction with oxygen and heat is produced. That is why, food is called fuel for our body.

Question 2.
Why does a piece of wood not burn by bringing a burning matchstick near it ?
Answer:
Wood has high ignition temperature. A burning matchstick cannot produce so much heat to reach the ignition temperature of wood. Therefore, wood does not burn.

Question 3.
Why is it important for all of us to know the telephone numbers of the fire service station?
Answer:
Who knows when and where suddenly fire breaks out. The fire brigade from the fire service station could be called when fire occurs anywhere. This can be -done only when we know the telephone numbers of fire- services.

Question 4.
How can the fire caused by burning liquid fuels be extinguished?
Answer:
It can be extinguished by throwing sand or soil over it.

Question 5.
Name two types of fire extinguishers.
Answer:
Soda acid fire extinguisher and hydrocarbon fire extinguisher are two types of fire extinguishers.

Question 6.
Name a substance which burns itself in air.
Answer:
Phosphorus.

Question 7.
Does charcoal produce a flame on burning?
Answer:
No, charcoal does not vaporise and so does not produce a flame.

Question 8.
Which gas is formed during the incomplete combustion of any fuel?
Answer:
Carbon monoxide gas.

Combustion and Flame Class 8 Extra Questions Short Answer Type 1

Question 1.
Define calorific value of fuel.
Answer:
Calorific value : The amount of heat energy produced on complete combustion of 1 kg of a fuel is called its calorific value. The calorific value of. a fuel is expressed in a unit called kilojoule per kg (kJ/kg). An ideal fuel has high calorific value.

Question 2.
Define ignition temperature.
Answer:
Ignition temperature is the lowest temperature at which a combustible substance catches fire. An ideal fuel should have a proper ignition temperature.

Question 3.
Define combustible and non-combustible substances.
Answer:
The substance that undergoes combustion is said to be combustible. The substance that does not undergo combustion is called non-combustible.

Question 4.
Define ignition temperature. Do all combustible substances have same ignition temperature ?
Answer:
The lowest temperature at which a substance catches fire, is called its ignition temperature. All combustible substances do not have same ignition temperature. In fact, each combustible substance has different ignition temperature.

Question 5.
Does combustible substance catch fire on its own ? Why?
Answer:
A combustible substance does not catch fire or bum on its own. It is so because a combustible substance does not catch fire as long as its temperature is lower than its ignition temperature.

Question 6.
Define spontaneous combustion.
Answer:
The type of combustion in which a material suddenly bursts into flames without the application of any apparent cause is called spontaneous combustion, e.g., combustion of coal dust.

Question 7.
What causes fires in coal mine ?
Answer:
Spontaneous combustion of coal dust results in many disastrous fires in coal mines.

Question 8.
What leads to deforestation ? What is its effect ?
Answer:
Cutting of trees leads to deforestation. It is quite harmful as it leads to global warming.

Question 9.
Is there any ideal fuel? If not, what is the alternative ?
Answer:
There is probably no fuel that could be considered as an ideal fuel. We should, as an alternative, look for a fuel which fulfils most of the requirements for a particular use.

Question 10.
What is global warming ? What causes it ?
Answer:
The increase in temperature of earth’s atmosphere is termed as global warming. The excess increase of carbon dioxide in atmosphere causes global warming because carbon dioxide facilitates green house effect, i.e., carbon dioxide traps hot radiations emitted by the earth’s surface.

Question 11.
What is done to extinguish fire due to burning of oil or petrol ?
Answer:
Fire produced by burning of oil or petrol can be controlled by throwing sand or soil over it.

Combustion and Flame Class 8 Extra Questions Short Answer Type 2

Question 1.
What is flame ?
Answer:
When a fuel is burned, a hot luminous gas emerges out of the burning fuel. This gas is called flame. Flames are a result of the substances which vaporize on burning. Example includes kerosene oil, wax, etc. which form flames on burning.

Question 2.
Explain greenhouse effect. Mention any two greenhouse gases.
Answer:
Greenhouse effect is warming of earth’s surface and atmosphere due to trapping »
of sun’s heat by certain gases in the earth’s atmosphere.

Water vapour, carbon dioxide, methane and certain other gases in the air are responsible for the Greenhouse effect. Of those gases, water vapour has the largest effect.

Question 3.
What is the role of water in extinguishing fire ?
Answer:
Water cools the combustible material, so that its temperature is brought below its ignition temperature. This prevents the fire from spreading. Water vapours also surround the combustible materials helping in cutting the supply of air. So, the fire is extinguished.

Question 4.
Why can we not use water to extinguish fire that is caused due to burning of oil or petrol ? ,
Answer:
When water is used to extinguish fire dur to burning of oil/petrol, water being heavier than oil/petrol settles down below it and it continues to burn. That is why we ~ cannot use water to extinguish fire in such a situation.

Question 5.
What would you do in case of fire produced by electric short circuit?
Answer:
In the case of fire caused by electric short circuit, water is not used at all because it is a conductor of electricity and may cause electrocution or electric shock.

The only solution is to cut off the supply of electricity and then use the spray of water on the flame to extinguish fire or use fire extinguisher.

Question 6.
What is the working methodology of fire extinguisher ?
Answer:
Fire extinguisher functions in one of the following ways:
(i) either it cuts off supply of air to the combustible substance.
(ii) or it brings down the temperature of the combustible substances well below its ignition temperature.

Question 7.
What are the causes of forest fires ? How can it be kept under control ?
Answer:
Forest fires sometimes occur due to the heat of the sun. However, most forest fires are due to the carelessness of human beings.

So, it is important to remember that the camp fires must be completely extinguished before leaving a forest after a picnic or any, visit and people should not throw any burning thing in the forest.

Question 8.
What do you mean by explosion? How does it take place ?
Answer:
Explosion is a sudden reaction in which heat, light, sound and large amount of gas is evolved. Explosion can also take place if pressure is applied on the cracker or any other combustible material kept in large amount.

Question 9.
What are the characteristics of an ideal fuel?
Answer:
The characteristics of an ideal fuel are:

1. It should be readily available,
2. It should be cheap,
3. It should bum easily in air at a moderate rate,
4. It should produce a large amount of heat, and
5. It should not leave behind any undesirable substances.

Question 10.
What are the disadvantages of burning wood in a chulha ?
Answer:
Disadvantages of burning wood in a chulha are :

1. It produces a lot of smoke, which causes respiratory problem.
2. Burning of wood leaves behind ashes, which are undesirable substances.
3. Cutting of wood for fuel leads to deforestation.

Question 11.
What are the disadvantages of global warming ?
Answer:
Global warming causes the rise in temperature of the atmosphere of the earth. This leads to melting of polar glaciers resulting into rise in sea level and causing floods in the coastal areas.

Combustion and Flame Class 8 Extra Questions Long Answer Type

Question 1.
What is the function of a fire extinguisher ? Describe various types of fire extinguishers.
Answer:
Fire extinguishers either cut off supply of air to the combustible substance or it brings down the temperature of the combustible substance well below its ignition temperature.

There are various types of fire extinguishers used for controlling fire:
(i) Soda acid fire extinguishers: It is based on the principle of cooling the fire. Carbon dioxide is liberated along with water. Water puts off the fire by lowering the temperature of the combustible material below its ignition temperature and carbon dioxide cuts off the supply of air to the combustible substances.

(ii) Hydrocarbon fire extinguishers:
It is based on the principle of covering burning material and cut off of oxygen supply to the fire. In this fire extinguisher sodium bicarbonate comes out under pressure in the form of a foam. The foam covers the whole surface of oil. It cuts off the supply of air and the fire is controlled.

Question 2.
What are the harmful effects of fuel consumption on the environment ? Describe.
Answer:
The increasing fuel consumption has the following harmful effects on the environment.

1. Carbon fuels like wood, coal, petroleum release unburnt, carbon particles. These particles are dangerous pollutants causing respiratory diseases, such as asthma.
2. Incomplete combustion (combustion in insufficient supply of oxygen or air) forms carbon monoxide gas. It is a very poisonous gas.
3. Combustion of most fuels releases carbon dioxide in the environment. Increased percentage of carbon dioxide in the air is believed to cause global warming.
4. Burning of coal and diesel releases sulphur dioxide gas. It is an extremely Suffocating and corrosive gas.
5. Petrol engines are responsible for the formation of nitrogen oxide gas.

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Coal and Petroleum Class 8 Extra Questions and Answers Science Chapter 5 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 5 Extra Questions and Answers Coal and Petroleum

Extra Questions for Class 8 Science Chapter 5 Coal and Petroleum with Answers

Coal and Petroleum Class 8 Extra Questions Very Short Answer Type

Question 1.
Name three natural resources.
Answer:
Air, water and soil.

Question 2.
Why air, water, minerals and soil are called natural resources ?
Answer:
Because they are provided by nature. Human beings cannot make them.

Question 3.
Name two inexhaustible natural resources.
Answer:
Sunlight and air.

Question 4.
Name two exhaustible resources.
Answer:
Wildlife and minerals.

Question 5.
Name the gas produced during destructive distillation of coal.
Answer:
Coal gas.

Question 6.
What happens when a burning matchstick is taken near the mouth of the outlet tube during destructive distillation of coal ?
Answer:
Coal gas catches fire.

Question 7.
Name the black residue left behind in the glass tube during destructive distillation of coal.
Answer:
It is coke.

Question 8.
What is the name of the process in which coal is heated in absence of air.
Answer:
The process is called destructive distillation of coal.

Question 9.
Name the pure form of carbon.
Answer:
The pure form of carbon is coke.

Question 10.
How is coal gas used nowadays?
Answer:
Nowadays the coal gas is used as a source of heat rather than light.

Question 11.
Where was the first oil well f drilled?
Answer:
The world’s first oil well was drilled at Pennsylvania, USA in 1859.

Question 12.
When and where was the first oil well drilled in India ?
Answer:
In 1867 at Makum in Assam.

Question 13.
What is the name of the process of separating the different constituents/ fractions of petroleum?
Answer:
It is called refining.

Question 14.
What is the full form of PCRA?
Answer:
Full form of PCRA is Petroleum Conservation Research Association.

Question 15.
What is termed as black gold?
Answer:
Coal is termed as black gold.

Coal and Petroleum Class 8 Extra Questions Short Answer Type 1

Question 1.
Define fossil fuel.
Answer:
Fossil fuel: The exhaustible natural resources like coal, petroleum and natural gas which were formed from the dead remains of living organism (fossils) are called fossil fuels, They are found in the earth’s crust.

Question 2.
Define LPG.
Answer:
LPG is Liquefied Petroleum Gas. It is obtained during fractional distillation of petroleum. Its main components are : butane and propane. It is used in filling cylinder and for cooking purpose. It is also used as an industrial fuel.

Question 3.
Define inexhaustible natural resources.
Answer:
Those resources, which are present in unlimited quantity in nature and arp not likely to be exhausted by human activities are called inexhaustible natural resources e.g., sunlight, air, etc.

Question 4.
Define exhaustible natural resources.
Answer:
The resources, which are present in limited quantity in nature and can be exhausted by human activities are called exhaustible natural resources e.g., forests, wildlife, minerals, coal, petroleum, natural%as, etc.

Question 5.
How were exhaustible natural resources formed?
Answer:
These were formed from the dead remains of living organisms (fossils). So, these are also known as fossil fuels.

Question 6.
What gas is produced when coal is heated in air? .
Answer:
When coal is heated in air, a gas called carbon dioxide (C02) is formed, which is a harmful gas and its presence in excess causes greenhouse effect and global warming.

Question 7.
Why is coal called fossil fuel ?
Answer:
Since coal was formed from the remains of the vegetations (plants), it is called a fossil fuel.

Question 8.
Define carbonisation.
Answer:
The slow process of conversion of dead vegetation into coal is called carbonisation.

Question 9.
What do you mean by destructive distillation ?
Answer:
The process of heating coa) in the absence of air (oxygen) is called destructive distillation.

Question 10.
From where naphthalene balls are obtained ? What is its use ?
Answer:
Naphthalene balls are obtained from the coal tar. These balls are used to repel” insects and moths.

Question 11.
What fuel is used in heavy motor vehicles ?
Answer:
Diesel is used as fuel in heavy motor vehicles.

Coal and Petroleum Class 8 Extra Questions Short Answer Type 2

Question 1.
Write any two uses of coke.
Answer:
Two uses of coke are :
(а) Coke is used in the manufacture of steel.
(b) Coke is used in the extraction of many metals.

Question 2.
Name the organisation in India which advises people ‘how to save petrol/ diesel’. Write its full form.
Answer:
In India, PCRA advises people ‘how to save petfoi/diesel’ while driving. PCRA give important and valuable tips necessary to follow while driving. The full form of PCRA is Petroleum Conservation Research Association.

Question 3.
What are the uses of coal gas ?
Answer:
(i) The coal gas is used as a fuel ip the coal processing plant and in many industries situated near the coal processing plants.
(ii) Earlier it was used for lighting but nowadays it is used as a source of heat.

Question 4.
What is petroleum? What is meant by refining?
Answer:
Petroleum is a dark oily liquid. It has an unpleasant smell. It is a mixture of various constituents such as petroleum gas, petrol, diesel, lubricating oil, paraffin wax, etc. The process of separating the different constituents/fractions is known as refining.

Coal and Petroleum Class 8 Extra Questions Long Answer Type

Question 1.
Write down five constituent of petroleum refining with their one use.
Answer:
Constituents of petroleum and their uses :

1. LPG: It is used as a fuel for home and industry.
2. Petrol: It is used as a motor fuel, aviation fuel, and solvent for dry cleaning.
3. Kerosene: It is used as a fuel for stoves, lamps and for jet aircraft.
4. Diesel: It is used as a fuel for heavy motor vehicles, electric generators.
5. Lubricating oil: It is used for lubrication of moving machinery parts like fans, motors, etc.
6. Paraffin wax: Paraffin wax is used for making ointments, candles, vaseline, etc.

Question 2.
Define the following:
(a) Crude oil
(b) Coke
(c) CNG
(d) PCRA
(e) Natural gas
Answer:
(a) Crude oil : Crude oil is a dark, oily liquid with an unpleasant smell obtained from the layers of the earth crust. It is popularly termed as Petroleum. The term ‘petroleum’ has been derived from the Latin words: ‘petra’ – which means rock and ‘oleum’ – which means oil.

(b) Coke: It is a tough, porous and black substance. It is almost pure form of carbon
and contains about 98% carbon. It is a good fuel and bums without smoke.

(c) CNG: Natural gas stored under high pressure in compressed form is called compressed natural gas (CNG). CNG is used for power generation. It is now being used as a fuel for transport vehicles because it is less polluting. It is a cleaner fuel.

(d) PCRA: PCRA advises people ‘how to save petrol/diesel’ while driving. PCRA give important and valuable tips necessary to follow while driving. The full form of PCRA is Petroleum Conservation Research Association.

(e) Natural gas : Natural gas is a fossil fuel found naturally as a gas mixture in the oil wells. Its main component is methane. Natural gas is a very important fossil fuel because it is easy to transport through pipes.

Question 3.
What is fuel ? Write down four characteristics of an ideal fuel ?
Answer:
A fuel is a substance that is burned to provide heat energy. Materials like coal, wood, diesel, natural gas etc. provide heat so used as fuels.
The characteristics of good fuel are :

1. It should be economical.
2. It should be available easily.
3. It should not emit poisonous gases on burning.
4. It should have a high calorific value.
5. It should be easy to transport and continues
6. It should leave very little or no ash after burning.

Question 4.
Today large demand of petroleum has increased its drilling from various resources. What will happen if it continues? What steps should be taken in order to mitigate such conditions?
Answer:
The alarming increase in the demand and its drilling can lead to the following consequence :
(a) The reserve or stock is limited, it will soon run away.
(b) Burning these fuels also cause air pollution as well as global warming.

In order to mitigate such situations, the following steps should be taken:
(а) We should use the fossil fuels judiciously so that they are available for a longer period.
(b) We must look for alternative sources, such as solar energy, tidal energy, wind energy, etc.

Hope the knowledge provided regarding the Coal and Petroleum Class 8 Extra Questions and Answers has helped you to the possible extent. For more info feel free to reach us and we will guide you at the earliest possibility. Stay connected to our site to avail latest updates on Extra Questions for Various Classes instantly.

Materials: Metals and Non-Metals Class 8 Extra Questions and Answers Science Chapter 4 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 4 Extra Questions and Answers Materials: Metals and Non-Metals

Extra Questions for Class 8 Science Chapter 4 Materials: Metals and Non-Metals with Answers 

Materials: Metals and Non-Metals Class 8 Extra Questions Very Short Answer Type

Question 1.
Do non-metals produce ringing sound?
Answer:
No, non-metals do not produce the ringing sound. It is a property of metals only.

Question 2.
List the characteristic properties of metals.
Answer:
The metals have the following properties:
(a) Hardness,
(b) lustre,
(c) malleability
(d) ductility,
(e) sonority, and
(f) good conductivity of heat and electricity.

Question 3.
Name some metals.
Answer:
Iron, copper, gold, aluminium, magnesium, etc.

Question 4.
Give some examples of non-metals.
Answer:
Sulphur, carbon, oxygen, phosphorus, calcium, etc.

Question 5.
Name two metals which can be cut with knife.
Answer:
Sodium and potassium are two metals which are soft and can be cut with a knife.

Question 6.
Name a metal which is found in liquid state at room temperature.
Answer:
Mercury.

Question 7.
Write the equation of rusting of iron.
Answer:
3Fe + 2H₂0 + 0₂ ➝ Fe₃O₄ + 2H₂

Question 8.
If the red litmus placed in a solution turns blue, the solution is called ________ hydroxides.
Answer:
Basic.

Question 9.
If the blue litmus paper turns red, the solution is called ________ hydroxides.
Answer:
Acidic.

Question 10.
When sulphur reacts in air (O₂), what is the product formed.
Answer:
It is sulphur dioxide (SO₂).

Question 11.
What is formed when sulphur dioxide is dissolved in water ? Also write the equation.
Answer:
Sulphurous acid is formed.
SO₂ + H₂O ➝ H₂SO₃
(Sulphurous acid)

Question 12.
What happens when a blue litmus paper is treated with an acid ?
Answer:
The blue litmus paper turns red.

Question 13.
Name the non-metals in the following acids:
Sulphuric acid (H₂SO₄), Hydrochloric acid (HC₁) and Nitric acid (HN0₃).
Answer:
Sulphur, chlorine and nitrogen respectively.

Question 14.
What happens when a small piece of sodium metal is placed in water?
Answer:
The metal piece starts moving in water with a hissing sound and then it catches fire.

Materials: Metals and Non-Metals Class 8 Extra Questions Short Answer Type 1

Question 1.
Why are metals used in making’ machinery?
Answer:
Metals are very hard, can withstand very high temperature and are strong as well as lustrous. That is why they are used “in making various machinery.

Question 2.
Define element.
Answer:
The substances made up of only one type of atoms are called element. Sulphur, iron, gold, calcium, hydrogen, etc. are elements. There are about 92 elements. Most of the elements are metals.

Question 3.
What is an atom?
Answer:
An atom is the smallest unit of an element. The atom of an element remains unaffected by any physical change in the element.

Question 4.
Describe how metallic and non- metallic oxides are formed.
Answer:
On burning, metals react with oxygen to produce metal oxides which are basic in nature. Non-metals react with oxygen to produce non-metallic oxides which are acidic in nature.

Question 5.
How can metals be distinguished from non-metals?
Answer:
Metals can be distinguished from non-metals on the basis of their physical and chemical properties.

Question 6.
Define malleability of a metallic substance.
Answer:
The property of metals by which they can be beaten into thin sheets, is called malleability. This is the characteristic property of metals.

Question 7.
Why is sodium stored in kerosene?
Answer:
Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. Therefore it is stored in kerosene to avoid its contact with air and water.

Materials: Metals and Non-Metals Class 8 Extra Questions Short Answer Type 2

Question 1.
Explain the construction of a water filter with materials available at home.
Answer:
(a) Cut off the bottom of a plastic bottle and place the bottle upside down into the vase or tall drinking glass.
(b) Place cotton balls, cloth, or a coffee filter inside the bottle as the first layer. Add an inch of activated charcoal as the second layer. Over the charcoal, add about two inches of small stones as the third layer and add about three to four inches of clean sand on top of the gravel.
(c) Add gravel to the bottle as the final layer. Leave about a half-inch of space from the top of the upside-down bottle.
(d) Pour the glass of muddy water on top of the homemade water filter and watch the water drip clean into the glass below.

Question 2.
How metal reacts with
(a) Oxygen
(b) Water and
(c) Acids
Answer:
(a) Metals react with oxygen and form their oxides.
Magnesium (Mg) + Oxygen (O₂) ➝ Magnesium Oxide (MgO)
Sodium (Na) + Oxygen (O₂) ➝ Sodium oxide (Na₂O)

(b) Metals react with water differently. Metals like sodium reacts with water vigorously and a lot of heat is produced. Whereas iron reacts with water slowly.
Sodium (Na) + Water (H20) ➝ Sodium hydroxide (NaOH) + Hydrogen gas (H₂)

(c) Metals react with dilute acids and produce hydrogen gas that burns with a ‘pop’ sound.
Zinc (Zn) + Hydrochloric acid (HCl) ➝ Sodium chloride (NaCl) + Hydrogen gas (H₂)

Question 3.
(a) What is a displacement reaction? Give an example for it.
(b) Which gas is released when acid reacts with a metal?
Answer:
(a) The chemical reaction in which a more reactive metal displaces/replaces a less reactive metal from its salt solution is called a displacement reaction. But a less reactive metal cannot replace a more reactive metal.

(b) Hydrogen gas is released when acid reacts with a metal.
Sodium (Na) + Water (H₂O) ➝ Sodium Hydroxide (NaOH) + Hydrogen gas (H₂)

Materials: Metals and Non-Metals Class 8 Extra Questions Long Answer Type

Question 1.
Write down three uses of metals and two uses of non-metals..
Answer:
Uses of metals :
(a) Metals are used in making machinery, automobiles, aeroplanes, trains, satellites and industrial gadgets, etc.
(b) Metals are used in making cooking utensils, water boilers, etc.
(c) Metals are used in making decorative arts, jewellery and coins.
(d) Aluminium foils are used for packaging medicines, chocolates, decorating sweets, wrapping food, etc.

Uses of non-metals :
(a) Non-metal essential for our life which all living beings inhale during breathing.
(b) Non-metals used in fertilisers to enhance the growth of plants.
(c) Non-metal used in water purification process.
(d) Non-metals used in crackers.

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Synthetic Fibres and Plastics Class 8 Extra Questions and Answers Science Chapter 3 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 3 Extra Questions and Answers Synthetic Fibres and Plastics

Extra Questions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics with Answers

Synthetic Fibres and Plastics Class 8 Extra Questions Very Short Answer Type

Question 1.
Name a synthetic fibre which is used in making cheap and durable woollen clothes.
Answer:
Acrylic.

Question 2.
Give one-word answer for the following :
Plastic which gets deformed easily on heating and can be easily bent.
Answer:
Thermoplastic

Question 3.
Complete the sentence:
Rayon is not a synthetic fibre because ____________.
Answer:
it is obtained from a natural source.

Question 4.
When was nylon made ?
Answer:
Nylon, a man-made fibre, was made in 1931.

Question 5.
Which one is stronger : a nylon wire or a steel wire ?
Answer:
Nylon wire.

Question 6.
What is the disadvantage of synthetic fibre ?
Answer:
The synthetic fabric melts on heating, which is a disadvantage of this fabric.

Question 7.
From which material, all synthetic fibres are prepared ?
Answer:
Synthetic fibres are prepared from petrochemicals.

Question 8.
What are manufactured from thermoplastics ?
Answer:
Toys, combs, car grills and various types of containers are manufactured from thermoplastics.

Question 9.
What are the characteristics of plastic due to which it is used to manufacture variety of articles?
Answer:

1. They have lightweight
2. lower price
3. good strength, and
4. are easy to handle.

Question 10.
Why is Plastic covering used in electric wires?
Answer:
It is because plastic is a poor conductor of electricity.

Question 11.
Why are handles of frying pans, cookers are made of plastic material ?
Answer:
It is so because plastic material is poor conductor of heat.

Question 12.
Why is plastic not environment friendly?
Answer:
Since plastic takes several years to decompose, it is not environment friendly.

Synthetic Fibres and Plastics Class 8 Extra Questions Short Answer Type 1

Question 1.
Explain, why the handles of cooking utensils, electric plugs, switches or plugboards are made of thermosetting plastics?
Answer:
The handles of cooking utensils, electric plugs, switches or plugboards are made of thermosetting plastics because:
(a) Thermosetting plastics cannot be softened by heating.
(b) They are poor conductor of heat and electricity.
(c) They resist fire and can tolerate heat.

Question 2.
What are the characteristic properties of synthetic fibres, due to which they are used abundantly?
Answer:
Synthetic fibres possess the following unique characteristics :

1. They dry up soon,
2. They are durable,
3. They are less expensive,
4. They are readily available, and
5. They are easy to maintain.

Question 3.
What is melamine? What are its uses?
Answer:
Melamine is a versatile thermosetting plastic. It resists fire and can tolerate heat better than other plastics. It is used for making floor tiles, kitchenware and fabrics which resists fire.

Question 4.
What is the characteristic property of plastic due to which it is used to make containers to store different materials?
Answer:
Plastics do not react with water and air and, therefore, they are non-corrosive in : nature. That is why, the containers made of plastics are used for storing various kinds of materials, including many chemicals.

Question 5.
Write a brief note on teflon.
Answer:
Teflon is a non-stick plastic used as non-stick coating in cookware. Because of its toughness, it is also used as tape for sealing purposes.

Synthetic Fibres and Plastics Class 8 Extra Questions Short Answer Type 2

Question 1.
Write a note on cross-linked plastic.
Answer:
Cross-linked plastic is that plastic in which its units possess cross-linked arrangements. The cross-linked plastics are available in all possible shapes and sizes. This is due to the fact that plastics are easily mouldable, i.e., plastic can be shaped in any form. That is why, various types of containers like water tank, water jug, bucket, mug, etc. are made of it arid used in day-to-day life.

Question 2.
Write a short note on the plastic in healthcare industry.
Answer:
Plastics find extensive use in the healthcare industry. Some examples of their use in healthcare are in packaging of medicines threads used for stitching wounds, syringes, gloves, a number of medical instruments, etc.

Question 3.
Write any five characteristics of synthetic fibres.
Answer:
The characteristics of synthetic fibers are :
(a) Synthetic fibres are cheaper than natural fibre.
(b) Synthetic fibres are stronger than natural fibre.
(c) Synthetic fibres are more durable than natural fibre.
(d) Synthetic fabrics are dried up in less time.
(e) Synthetic fibres are easy to maintain and wash.
(f) Synthetic fibres are readily available and easy to maintain.

Synthetic Fibres and Plastics Class 8 Extra Questions Long Answer Type

Question 1.
Write a note on rayon.
Answer:
Natural silk from silkworm was discovered in China and was kept as a closely guarded secret for a long time. Silk was a costly fabric. But, as its texture was beautiful, it fascinated everybody. So, people began to think of preparing silk artificially.

Towards the end of the nineteenth century, scientists were successful in obtaining a fibre having the properties similar to that of silk. Such a fibre was obtained by chemical treatment of wood pulp. This fibre was called rayon or artificial silk. Although rayon is obtained from’a natural source, wood pulp, yet it is a man-made fibre. It is cheaper than silk, but can be woven like silk fibres. It can also be dyed in a wide variety of colours.

Question 2.
What are renewable and non-renewable sources of energy? What will happen if all the non-renewable resources get exhausted?
Answer:
Renewable sources of energy:
The sources of energy, which are being produced continuously in nature and are inexhaustible, are called renewable sources of energy. These sources of energy can be used again and again, endlessly. They will never get exhausted. For example, wind, sunlight.

Non-renewable sources of energy :
The sources of energy, which have accumulated in nature over a very, very long time and cannot be quickly replaced when exhausted, are called non-renewable sources of energy, e.g., coal. If all non-renewable sources of energy get exhausted, we will have to depend on renewable sources of energy. More and more alternative sources will have to be developed.

Question 3.
(a) You have to buy clothes to wear in summer. You will prefer to buy cotton clothes or clothes made of synthetic material. Give reason for your answer.
(b) Which material is better for making umbrella and why ?
Answer:
(a) I will prefer to buy cotton clothes over synthetic clothes. This is because cotton clothes absorb more sweat than synthetic clothes. I will comfortable and cool in cotton clothes than synthetic clothes.
(b) Synthetic cloth is better for making an umbrella because

1. Synthetic fibre is more durable.
2. Synthetic fibre is stronger.
3. Synthetic fibre absorb less water.
4. Synthetic fibre is lightweight as compared to cotton cloth.

Question 4.
“Even though plastics are very useful, they are not environment friendly.” Justify the statement.
Answer:
Even though plastics are very useful and have vital applications in our daily life but they are not environment friendly because :
(а) The plastics are not bio-degradable and take several years to decompose. It causes environmental pollution.
(b) The-burning process in the synthetic material is quite slow and it does not get completely burnt easily. In the process it releases lots of poisonous fumes into the atmosphere causing air pollution.

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Microorganisms: Friend and Foe Class 8 Extra Questions and Answers Science Chapter 2 PDF are solved by experts and will guide students in the right direction. Students can get how to tackle different questions easily by solving the Extra Questions for Class 8 Science Question bank on a regular basis.

Class 8 Science Chapter 2 Extra Questions and Answers Microorganisms: Friend and Foe

Extra Questions for Class 8 Science Chapter 2 Microorganisms: Friend and Foe with Answers

Microorganisms: Friend and Foe Class 8 Extra Questions Very Short Answer Type

Question 1.
Write the agent that is responsible for the spread of following diseases:
Polio =________
Tuberculosis = _________
Answer:
Polio = Viruses
Tuberculosis = Bacteria

Question 2.
Write the name of bacteria which converts milk into curd.
Answer:
Lactobacillus

Question 3.
Name two diseases caused by protozoans.
Answer:
Diseases like dysentery and malaria are caused by protozoans.

Question 4.
Name two diseases caused by bacteria.
Answer:
Typhoid and tuberculosis (T.B.).

Question 5.
Where are microbes found?
Answer:

1. They are present everywhere because they can survive under all types of environments.
2. They are also found inside human body.

Question 6.
What are the commercial uses of yeast?
Answer:
Yeast is used for commercial production of alcohol and wine.

Question 7.
Name the process of conversion of sugar into alcohol.
Answer:
Fermentation.

Question 8.
Who discovered the process of fermentation?
Answer:
Louis Pasteur in 1857.

Question 9.
Who discovered Penicillin?
Answer:
Alexander Fleming discovered the antibiotic called Penicillin in 1929.

Question 10.
Name some of the diseases that can be prevented by vaccination.
Answer:
Cholera, tuberculosis, smallpox, hepatitis, etc.

Question 11.
Who discovered the vaccine for smallpox?
Answer:
Edward Jenner discovered the vaccine for smallpox in 1798.

Question 12.
Can you name some diseases for which you have been given injection in your childhood to protect you from them?
Answer:
They are diphtheria, tuberculosis, chiekenpox, cholera, etc.

Question 13.
What is the most prominent role of microorganisms in pollution control?
Answer:
They degrade the harmful substances and thereby play prominent role in pollution control.

Microorganisms: Friend and Foe Class 8 Extra Questions Short Answer Type 1

Question 1.
Define microorganisms with two examples.
Answer:
A microorganism is a living thing that is too small that it can’t be seen with the naked eye. Microorganisms can be found in air, water and in the bodies of plants and animals. They may be unicellular or multicellular.

For Example:
Bacteria: Lactobacillus
Protozoa: Amoeba, Paramecium

Question 2.
How do microorganisms help to improve the fertility of soil?
Answer:
Rhizobium bacteria present in the nodules of the roots of leguminous plants helps in the replenishment of the soil with nitrogen. Rhizobium bacteria takes nitrogen from the atmosphere and fix it directly into nitrogenous compounds and increase the fertility of the soil.

Question 3.
Seema took 50 gm of flour (atta) and added some sugar and mixed it with warm water„and also added small amount of yeast powder into it:
Write the observation noted by her after two hours.
What is the function of yeast in this activity?

Answer:
(i) After two hours the flour (atta) is found to be raised a little bit.
(ii) Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the carbon dioxide gas fill the flour mix and increase its volume. This is the basis of the use of yeast in the baking industry for making breads, pastries and cakes.

Question 4.
What is pseudopodia? Write down two examples.

Answer:
Pseudopodia: A pseudopodium is a temporary arm-like projection of the cell of a microorganism.

Examples :
Pseudopodia are used for motility.
Pseudopodia are used for ingestion.

Microorganisms: Friend and Foe Class 8 Extra Questions Short Answer Type 2

Question 1.
(a) What are antibiotics?
(b) Name any two antibiotics?
(c) How are antibiotics manufactured?

Answer:
(a) Antibiotics are the medicines which kill or stop the growth of the disease-causing microorganisms. The source of these medicines is micro­organisms.
(b) Streptomycin, Tetracycline.

(c) The antibiotics are manufactured by growing specific microorganisms which checks the growth of some other bacteria or microorganisms. Antibiotics are used to cure a variety of diseases. They are also used to control many plant diseases.

Question 2.
How are bacteria beneficial to us? Explain by giving any three examples.
Answer:
Bacteria are very useful to human beings though some other bacteria are harmful too.

Following are some examples that are very useful to us :

(a) Rhizobium: Rhizobium bacteria and blue-green algae present in the soil fix nitrogen from the atmosphere and convert into nitrogenous compounds.
(b) Lactobacillus: Lactobacillus bacteria is useful in making curd from milk.
(c) Decomposers: Bacteria play an important role in cleaning the environment by decomposing the dead organic matter.

Question 3.
How can nitrogen be replenished in soil? Explain with an example.
Answer:
Nitrogen in the soil can be replenished by two different ways:

Rhizobium bacteria present in the nodules of the roots of leguminous plants helps in the replenishment of the soil with nitrogen. Rhizobium bacteria takes nitrogen from the atmosphere and fix it directly into nitrogenous compounds. These crops are like beans and peas which with which it has a symbiotic relationship Rhizobium.

Nitrogen sometimes gets fixed through the action of lightning in the clouds. High temperature generated in the lightening fixes the nitrogen to nitrogenous compounds.

Microorganisms: Friend and Foe Class 8 Extra Questions Long Answer Type

Question 1.
What is nitrogen cycle? Describe with the help of a diagram how nitrogen- cycle works.
Answer:
The process of consumption of nitrogen by living beings (animals and plants), taking it from the atmosphere and returning back to the atmosphere by various processes, is called nitrogen cycle.

Nitrogen-cycle:

(i) Nitrogen is one of the essential constituents pf all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins.
(ii) The atmospheric nitrogen cannot be taken directly by plants and animals.
(iii) The nitrogen-fixing bacteria and algae present in the soil fix nitrogen from the atmosphere and convert into nitrite and nitrate forms.
(iv) Once nitrogen is converted into these usable forms, it can be utilized by plants through their roots. This is called the process of ‘fixing of nitrogen.
image
(v) Nitrogen is then used for the synthesis of amino acids, proteins, etc. in plants. Animals feeding on the plants thus get these nitrogen-containing compounds.
(vi) When plants and animals die, bacteria and fungi present in the soil convert the various compounds of nitrogen back to nitrates and nitrites. Certain specialized bacteria convert nitrates and nitrites into nitrogen gas which goes back into the atmosphere. As a result, the percentage of nitrogen in the atmosphere remains more or less constant. This is how nitrogen-works.

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