Marksparks .arkansas

CBSE Class 8 Science Chapter 2 Short Answer Questions

Question 1. Why should we avoid standing close to a tuberculosis patient while he or she is coughing?
Answer: Tuberculosis is an airborne disease that easily spreads when the infected person coughs, as coughing spreads germs in the air. This bacterium can be inhaled by a healthy person nearby and cause infection. This is why we should avoid standing close to a TB patient.

Question 2. Classify the following into friendly and harmful microorganisms.
Yeast, malarial parasite, Lactobacillus, bread mould, Rhizobium, Bacillus anthracis.
Answer: 

Question 3. While returning from school, Boojho ate chaat from a street hawker. When he reached home, he fell ill and complained of a stomachache. What could be the reason?
Answer: The reason could be that the chaat was contaminated by pathogenic microorganisms. It can be due to unhygienic conditions near the shop, or the utensil used for serving could have been contaminated.

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The unhygienic environment of the shop attracts flies and promotes the growth of infections. Most street hawkers sell food items in an open area, which gets contaminated with dust and flies carrying germs. This unhygienic condition can lead to the spoilage of food, which, when consumed, can lead to serious illness.

Question 4. What will happen to ‘poorls’ and ‘unused kneaded flour’ if they are left in the open for a day or two?
Answer: The ‘unused kneaded flour’, if left in warm conditions, gets infected by microbes which cause fermentation and spoil the flour. The pooris, on the other hand, would remain in relatively good condition because these were deep-fried in heated oil that kills microbes.

Explain how Lactobacillus is useful In Making Curd, Class 8 CBSE

Question 5. Sachin opened two packets of Milo drink. He left one in the refrigerator and another on the table. Three days later, he got a bad smell from the packet left on the table. The packet of Milo drink in the refrigerator did not have a bad smell. Why? Explain.
Answer: The packet, which was put in the refrigerator, did not have a bad smell because there was a cold temperature, and bacteria could not grow there. The Milo drink left outside the refrigerator smelled bad because it came in contact with air and bacteria. The higher temperature outside the refrigerator proved favourable for the growth of microorganisms.

CBSE Class 8 Science Chapter 2 Microorganisms: Friend And Foe Very Short Answer Questions

Question 1. Write the name of the device by which we can study microorganisms successfully.
Answer: A Microscope is the device that has made the study of microorganisms successful.

Question 2. Ashish left an orange in his bag and forgot about it. After a week, when he looked in his bag, he found something growing on his orange.

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Question 3. What was growing on Ashish’s orange?
Answer: Mould

Question 4. Can these organisms be seen with a magnifying glass?
Answer: Yes, Fungi can be seen with a magnifying glass.

Question 5. Identify a protozoan from the list of microorganisms given: Rhizopus, Rhizobium, Penicillium, and Amoeba.
Answer: Amoeba is a protozoan in the list given.

Question 6. Name the group of microorganisms that can photosynthesise.
Answer: Algae are a group of microorganisms that can photosynthesise.

Question 7. Mention the kind of organisms that are classified under algae. Give examples.
Answer: Simple plant-like organisms that contain chlorophyll are classified under algae. Example: Spirogyra, Chlamydomonas.

Question 8. Mention a characteristic of viruses.
Answer: Viruses are cellular, tiny, microscopic organisms that can reproduce only inside the cells of host organisms.

Question 9. Write the names of two groups of microorganisms that live in colonies.
Answer: The groups of microorganisms that live in colonies are bacteria and fungi.

CBSE Class 8 Science Chapter 2 Microorganisms, Friend And Foe Activity Ideas Activity 1

Aim: To show the presence of microorganisms in soil and pond water.

Materials Required: Soil, water, two beakers, pond water, microscope, dropper, and slide.

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Procedure

1. Collect some moist soil from the field in a beaker A and add water to it.
2. Take another beaker, B, and pour some pond water into it.
3. After the soil particles have settled down, put a drop of water from the beaker A with the help ofdropper on a slide and observe under a microscope.
4. Similarly, take a few drops of water from beaker B with the help ofdropper, spread them on a glass slide and observe through a microscope.

Observation: We will observe tiny organisms moving around in both slides.

Conclusion: From this activity, we can conclude that soil and pond water contain many microorganisms.

CBSE Class 8 Science Chapter 2 Microorganisms Activity For Better Understanding Activity 2

Aim: To show the effect of yeast on dough.

Materials Required: 1/2 kg Flour (atta or maida), sugar, warm water, yeast powder, and a lid.

Procedure:

1. Take 1/2 kg flour (atta or maida), add some sugar, and mix with warm water.
2. Add a small amount of yeast powder and knead to make a soft dough.
3. Cover the dough and keep it aside for two hours.

Observation: We will observe that the dough has risen and its volume has increased

Conclusion: From this activity, we can conclude that yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume.

Class 8 Science Chapter 2 Microorganisms: Friend And Foe Activity 3

Aim: To carry out the fermentation of sugar.

Materials Required: Beaker, water, sugar, yeast powder, lid, and spoon.

Procedure

1. Take a 500 mL beaker filled upto 3/4 with water.
2. Dissolve 2-3 teaspoons of sugar in it.
3. Add half a spoonful of yeast powder to the sugar solution.
4. Keep it covered with a lid in a warm place for 4-5 hours.
5. Smell the solution.

Observation: We will observe a pungent smell

Conclusion: From this activity, we can conclude that sugar has been converted into alcohol by yeast. This process of conversion of sugar into alcohol is known as fermentation.

CBSE Class 8 Science Chapter 2 Microorganisms Activity With Materials List Activity 4

Aim: To show that microorganisms decompose plant waste.

Materials Required: Pot A and B, soil, plant waste, polythene bag, empty glass bottles, and broken plastic toys.

Procedure:

1. Take two pots and fill each pot half with soil, and mark them A and B.
2. Put plant waste in pot A
3. Put polythene bags, empty glass bottles, and broken plastic toys in pot B.
4. Put both pots aside. Observe them after 3-4 weeks.

Observation: We will observe that the contents of pot A would be converted into manure by the action of the microbes present in the soil. However, there would be no change in the contents of pot B, as microorganisms could not act on the materials present in it

Conclusion: From this activity, we can conclude that microorganisms decompose plant waste and convert it into manure, but they do not act on inorganic substances like polythene bags, plastic toys, etc.

CBSE Class 8 Science Chapter 12 Some Natural Phenomena Multiple Choice Questions

Question 1. We see lightning first than sound because

1. Sound travels farther than light
2. Light travels faster than sound
3. Light travels In vacuum but sound dose not
4. None of the above

Answer: 2. Light travels faster than sound

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Question 2. The magnitude or Intensity of an earthquake can be measured by

1. Electroscope
2. Richlor scale
3. Both 1 and 2
4. None of those

Answer: 2. Richlor scale

Question 3. The continuous motion of the plates inside Earth’s crust causes

1. Cyclone
2. Rain
3. Earthquake
4. Thunderstorm

Answer: 3. Earthquake

Question 4. The innermost layer of Earth is called

1. Crust
2. Mantle
3. Core
4. None of these

Answer: 3. Core

Question 5. Lightning occurs due to

1. Rain
2. Wind
3. Electric discharge
4. None of these

Answer: 3. Electric discharge

Question 6. Sparks can be seen on the electric poles, due to which the wire becomes

1. Loose
2. Tight
3. Wrinkle
4. None Of These

Answer: 1. Loose

Question 7. The like charges

1. Repel Each Other
2. Attract Each Other
3. No Interaction Takes Place
4. All Of The Above

Answer: 1. Repel Each Other

Question 8. The charge acquired by the glass rod when it is rubbed with a silk is

1. Positive
2. Negative
3. Both 1 and 2
4. None of these

Answer: 1. Positive

Question 9. Two charged objects are brought close to each other. Choose the most appropriate statement from the following options.

1. They may attract.
2. They may repel.
3. They may attract or repel depending on the type of charges they carry.
4. There will be no effect.

Answer: 3. They may attract or repel depending on the type of charges they carry.

Question 10. Which of the following can be charged with static electricity?

1. Alloy
2. Metal
3. Insulator
4. Semiconductor

Answer: 3. Insulator

Question 11. Electric current is to be passed from one body to another. For this purpose, the two bodies must be joined by

1. Cotton Thread
2. Plastic String
3. Copper Wire
4. Rubber Band

Answer: 3. Copper Wire

Question 12. Consider the list of terms given below

1. Tsunami
2. Landdslide
3. Flood
4. Lightning

Question 13. Earthquakes can cause

1. 1, 2, and 3
2. 2 and 5
3. 2, 3, and 4
4. 3 and 4

Answer: 1 1, 2, and 3

CBSE Class 8 Science Chapter 12 Some Natural Phenomena Long Answer Questions

Question 1. In the year 2013. There was a showcase at IIT Hyderabad. All the students from different schools and colleges were invited to that occasion. Navecn, with his friend wanted to so the projects made by M. Touch students. Ho found a project based on the construction of anti-earthquake buildings, in which the small houses of iron rods were constructed. One Muse was with a hose containing water, and the other was without a hose. They were shocked by the shaking of both houses.

1. Describe an earthquake.
Answer: A sudden shaking of the earth, which lasts for a very short time, is called an earthquake.

2. Explain the meaning of a quake-resistant building.
Answer: Quake-resist building means that the buildings should be constructed in such a way that it can withstand for more time even on shaking of the earth.

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3. Mention which force reduces the shaking in a building with a hose.
Answer: The viscous force of water resists the oscillation or vibration of building caused by shaking of the earth and ultimately reduces the shaking in building with hose.

4. State your feelings about the students who showed their projects.
Answer: They used applications of science and technology and were more curious about the methods.

Question 2. Amit was travelling in a taxi when he saw lightning at some distance. He heard thunder after a few seconds.

1. What should Amit do immediately to remain safe?

1. Increase the speed of the car
2. Stop the car and remain seated inside
3. Stop the car and take shelter inside a building
4. Turn the car and travel in the opposite direction

Answer: 2. Stop the car and remain seated inside

2. Which of these conditions results in lightning?

1. Negative and positive charges meeting
2. The number of negative charges is increasing
3. The number of positive charges is increasing
4. Negative and positive charges are moving away from each other.

Answer: 1. Negative and positive charges meeting

3. A lightning conductor protects a building from lightning. What is a lightning conductor made of?

1. Glass
2. Metaal
3. Wood
4. Plastic

Answer: 2. Metaal

Question 3. The diagram shows the focus of an earthquake. Focus is the point inside the Earth’s crust where the earthquake originates. 1, 2, 3, and 4 are four locations on the Earth’s surface.

1. In which location will the effect of the earthquake be maximum?

1. Location 1
2. Location 2
3. Location 3
4. Location 4

Answer: 2. Location 2

2. Raju was in his garden when an earthquake hit the place. What should Raju do to remain safe?

1. Move to an open space
2. Run away from the place
3. Take shelter under a staircase
4. Take shelter under a large tree

Answer: 1. Move to an open space

Question 4. The Richter scale measures the strength of earthquakes

1. The damages from an earthquake are listed below.

1. 2 people died
2. 5 building roofs collapsed
3. 12 building walls collapsed

What could be the likely reading on the Richter scale for the earthquake?

1. 4.8
2. 5.4
3. 6.5
4. 7.3

Answer: 3. 6.5

Question 5. Which of these statements is true about the earthquake?

1. Earthquakes can cause soil erosion.
2. Most of the earthquakes occur in mountain regions.
3. The location and duration of earthquakes can be predicted.
4. Earthquakes are caused by the movement of underground plates.

Answer: 4. Earthquakes are caused by the movement of underground plates.

Question 6. Ryan ran two combs through his hair. He hung one comb from a stand using a thread. Ryan brought the other comb close to the first comb. The picture below shows the result.

1. Why did the comb move away from the other?
Answer: The comb moved away from the other because both the combs acquired the same or like charges when they were run through hair, and like charges repel each other.

2. Ryan repeats the activity using a pair of glass rods in place of the combs. What is most likely to happen in this case?

1. The hanging rod will move away
2. The hanging rod will come closer
3. The hanging rod will show no change
4. The hanging rod will start spinning.

Answer: 1. The hanging rod will move away

Question 7. Describe with the help of a diagram, an instrument that can be used to detect a charged body.
Answer: The instrument that is used to detect a charged body is an electroscope.

Construction

1. Take an empty jam bottle.
2. Take a piece of cardboard slightly bigger in size than the mouth of the bottle.
3. Pierce a hole in it so that a metal paper clip can be inserted.
4. Open out the paper clip.
5. Cut two strips of aluminium foil about 4 X 1 cm each. Hang them on the paper clip.
6. Insert the paper clip into the cardboard so that it is Perpendicular to it.
7. Charge a refill and touch it with the end of the paper clip.

Working

The aluminium foil strips receive the same charge from the charged refill through the paper clip. The strips carrying the same charge repel each other, and they become wide open.

Touch the end of the paper clip gently with your hand, and we will find a change in the foil strip. Repetition gives the same result.

CBSE Class 8 Science Chapter 3 Coal And Petroleum MCQs With Answers Multiple Choice Questions And Answers

Question 1. Various materials that are obtained from nature are called natural resources. Which of the following is not a natural resource?

1. Minerals
2. Water
3. Soil
4. Plastic

Answer: 4. Plastic

Question 2. The source of energy for the Earth’s water cycle is

1. Seas
2. Sun
3. Earth’s rotation
4. Minerals

Answer: 2. Sun

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Question 3. Air is a natural resource and cannot be exhausted by human activities. It is known as an inexhaustible natural resource. Which of the following is another Inexhaustible natural resource?

1. Coal
2. Petroleum
3. Sunlight
4. Minerals

Answer: 3. Sunlight

Question 4. Which of the following is a pair of non-renewable natural resources?

1. Coal and soil
2. Air and sunlight
3. Water and petroleum
4. Trees and minerals

Answer: 3. Water and petroleum

Question 5. Exhaustible natural resources are

1. Made by human efforts
2. Not dependent on nature
3. Limited in quantity
4. Not exhausted by human activities

Answer: 3. Limited in quantity

Question 6. Which of the following is an exhaustible natural resource?

1. Soil
2. Air
3. Sunlight
4. Coal

Answer: 4. Coal

Question 7. Fossil fuels are obtained from

1. Remains of non-living materials
2. Dead remains of birds only
3. Dead remains of insects only
4. Dead remains of living organisms

Answer: 4. Dead remains of living organisms

Question 8. Coal is formed from the remains of

1. Vegetation only
2. Animals only
3. Both vegetation and animals
4. Neither vegetation nor animals

Answer: 3. Both vegetation and animals

Question 9. Which substance is formed by the carbonisation of dead vegetation?

1. Coal
2. Coke
3. Coal gas
4. Coal tar

Answer: 1. Coal

Question 10. When coal burns in the air

1. Nitrogen is formed
2. Sulphur dioxide is formed
3. Oxygen is formed
4. Carbon dioxide is formed

Answer: 4. Carbon dioxide is formed

Question 11. Coal is processed in Industries to got some useful products. Which of the following Is not obtnlnod from coal?

1. Coke
2. Coal tar
3. Coal gas
4. CNG

Answer: 4. CNG

Question 12. Which by-product is obtained after processing coal?

1. Diesel
2. Petrol
3. Coke
4. Paraffin wax

Answer: 3. Coke

Class 8 Science Chapter 12 Some Natural Phenomena Activity 1

Aim: To prove that an object gets electrically charged by rubbing.

Material Required: A ball pen refill, a small piece of paper, dry leaf, polythene, etc.

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Procedure 

1. Firstly, take a ball pen refill and rub it vigorously with a piece of polythene.
2. Now, bring it close to a piece of paper. Be ensure that the rubbed part of the refill should not be touched by our hand. We will find that the refill attracts the tiny pieces of paper.
3. Repeat the activity with small pieces of dry leaf, husk, and mustard seeds and note down the observation. We will find that the refill attracts the tiny pieces in each case.

Conclusion: We can conclude that when the plastic refill is rubbed with polythene, dry leaf, or mustard seeds, etc., it acquires a small electric charge.

Class 8 Science Chapter 12 Some Natural Phenomena Activity 2

Aim: To record that different objects get electrically charged when rubbed with different materials.

Material Required: Refill, balloon, eraser, steel spoon, polythene, dry hair, silk cloth.

Procedure:

1. Collect the objects given in the table and rub them against the materials listed next to them in the table.
2. Bring the charged object (rubbed object) close to tiny pieces of paper and observe, it attracts or not.
3. Record your observations in the table.

Conclusion: We have concluded from the observation table that the objects rubbed with different materials get charged and attract tiny pieces of paper, except the steel spoon, because it is a good conductor.

Class 8 Science Chapter 12 Some Natural Phenomena Activity 3

Aim: To understand the interaction between two types of electric charges.

Material Required: Two inflated balloons, two refills, woollen cloth, polythene.

Procedure:

• Firstly, hang two inflated balloons in such a way that they do not touch each other.
• Now, rub both the balloons with a woollen cloth and release them.
• We will observe that both balloons start repelling each other. They both acquire the same negative charge.

• Now, bring a plastic refill and rub it with polythene. It with acquire some charge.
• Place this charged plastic refill in a glass tumbler using the tumbler as a stand.
• Now, take another plastic refill and rub it with polythene and bring it close to the charged refill, which is already placed in a glass tumbler.

We will find that. The charged refill in the tumbler moves away. It means both the refills repel each other, as they acquire the same charges, that is positive charge.

• Again, rub a refill with polythene and place it gently in a glass tumbler as before.
• Now, bring an inflated charged balloon near the refill.

We will observe that the charged refill moves towards the charged balloon. As they both acquire different charges.

Conclusion: We have concluded from the activity that like charges repel each other and unlike charges attract each other.

Class 8 Science Chapter 12 Some Natural Phenomena Activity 4

Aim: To understand the working ofan electroscope. Material Required: An empty jam bottle, a cardboard, a metal paper clip, two small pieces of aluminum foil, and a refill.

Procedure:

1. Choose an empty jam bottle and take a piece of cardboard slightly bigger in size than the mouth of the bottle.
2. Now, pierce a hole in the cardboard so that a metal paper clip can be inserted.
3. Cut two strips of aluminum foil about 4cm x 1 cm each. Hang them on the paper clip as shown in the figure.
4. Now, fix the paper clip in the cardboard lid, so that it gets perpendicular to it as shown in the figure.
5. Now, charge a refill and touch it with the end of the paper clip. We can see that the two aluminium foils move away from each other.
6. Gently, touch the other charged bodies with the ends of a paper clip. Here, we find no differences in the working of foil strips.

Conclusion: We have concluded that a charged body transfers all its charges to aluminium foil through a paper clip

Which causes the aluminium leaves to diverge. Therefore, the greater the amount of electric charge on a body, the greater the aluminium leaves will diverge.

Class 8 Science Chapter 12 Some Natural Phenomena Activity 5

Aim: To prepare a short report on the suffering of the people during and after the earthquakes.

Material Required: Newspapers, magazines.

Procedure:

1. Collect some newspapers and magazines from different publishers.
2. Read the articles carefully based on the earthquakes.
3. Now, collect some pictures showing the damage caused by these earthquakes from these newspapers and magazines.
4. Make a short report on the destruction caused by earthquakes.

Conclusion: An Earthquake is a natural calamity. It is a sudden shaking or trembling of the earth which lasts for a short time. Some of the damaging effects ofan earthquake are as follows

1. The earthquake may cause landslides and tsunamis in hilly and coastal areas.
2. An earthquake may break a groundwater pipe, which disrupts the water supply system.
3. An earthquake brings destruction to buildings, dams, railway tracks, roads, etc.
4. The earthquake may cut off the communication system, and the affected areas may get disconnected from the rest of the world.

Class 8 Science Chapter 12 Some Natural Phenomena Activity 6

Aim: To make a report of some devastation caused by the tsunami in India.

Material Required: A political world map.

Procedure:

1. Firstly, take a world map.
2. Now, locate the eastern coast and the Andaman and Nicobar islands in India. Mark other countries around the Indian Ocean that could have suffered damage from the tsunami.
3. Now, collect some information from your parents or other elders to make a report of the devastation caused by the tsunami in India.
4. Prepare a report in neat and clean handwriting.

Conclusion: We have located the eastern coast of India, the Andaman and Nicobar Islands, and other countries around the Indian Ocean.

Some information about the devastation caused by the tsunami in India is given above.

A major tsunami occurred in the Indian Ocean on 26th December 2004. At 8:38 AM, an earthquake of 6.1 magnitudes was felt in Andaman Island. At 9:00 AM, this affected India’s South-Eastern coast.

Thousands of people died, and many people lost their families. The coastal area was destroyed. Many fisherman and their community were ruined by the tsunami. It was one of the most devastating natural calamities, people have ever witnessed.

Class 8 Science Chapter 12 Some Natural Phenomena Fill In The Blanks

Question 1. When charges move, they constitute an electric current.
Answer: Electric

Question 2. __________types of charges are gained by rubbing objects.
Answer: Two

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Question 3. The process of transfer of charge from a charged object to the Earth is called
Answer: Earthing

Question 4. A lightning strike could destroy__________ and
Answer: Life, Property

Question 5. Lightning conductor can_____________ buildings from the effect of lightning.
Answer: Protect

Question 6. An earthquake is caused by a _______ deep inside the Earth’s crust.
Answer: Disturbance

Question 5. Static charges can be induced by ________.
Answer: Rubbing

Question 6. ________ is a device used to protect buildings from the effects of lightning.
Answer: Lightning conductor

Question 7. An earthquake is caused due to the movement of plates in the Earth’s crust.
Answer: Tectonic

Class 8 Science Chapter 12 Some Natural Phenomena True Or False

Question 1. The process of electric discharge cannot occur between clouds and the Earth.
Answer: False

Question 2. Bathing outdoors should be avoided during a thunderstorm.
Answer: True

Question 3. Earthquakes can occur anytime, all over the world.
Answer: True

Question 4. The plates of the outermost layer of the Earth are always in continuous motion.
Answer: True

Question 5. Tremors on the Earth can be caused by the eruption of a volcano
Answer: True

Class 8 Science Chapter 12 Some Natural Phenomena Match The Columns

Answer: A-7,B-4,C-1,D-2,E-3,F-4,G-5

Class 8 Science Chapter 12 Some Natural Phenomena Assertion-Reason Questions

The following questions consist of two statements -Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false
4. A is false, but R is true.

Question 1.

Assertion (A): Maximum damage occurs at the epicentre.
Reason (R): The Destructive energy of an earthquake is measured on the Richter scale.

Answer: 2. Both A and R are true, but R is not the correct explanation of A.

Question 2.

Assertion (A): We should not use an umbrella while crossing an open field during a thunderstorm.
Reason (R): As the rod of the umbrella and its supporting wires are made up of metals, it may affect the person who holds the umbrella

Answer: 1. Both A and R are true, and R is the correct explanation of A.

The following questions consist of two statements: Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.

Question 1.

Assertion (A) The most destructive earthquakes have a magnitude of more than 7 on the Richter scale.
Reason (R) We should move inside our houses or tall buildings during earthquakes.

Answer: We should not move inside our house or tall buildings during an earthquake because tall buildings may collapse and cause an accident.

Question 2.

Assertion (A) A charged body repels an uncharged body.
Reason (R) Like charges repel each other while unlike charges attract each other.

Answer: A charged body always attracts an uncharged body

Question 3.

Assertion (A): An earthquake is a sudden shaking or trembling of the earth which lasts for a short time.
Reason (R): The plates inside the Earth’s crust collide with one another, which causes earthquakes.

Answer: Earthquakes are caused by sudden shaking and the collision of plates inside Earth’s crust.

Question 4.

Assertion (A): An electroscope is a device that is used to test whether an object is carrying a charge or not.
Reason (R): The Electroscope is based on the transfer of charges.

Answer: An Electroscope determines whether any object is charged or not by the transfer of charges.

CBSE Class 8 Science Chapter 3 Coal And Petroleum Long Answer Questions

Question 1. Ravi prefers to go to school by pooling car. On other occasions he likes to opt for public transport rather than private transport. For short distances, he walks or uses a bicycle.

1. Which means of transport do you think is best for short distances?

1. Small vehicles
2. Bicycles
3. Large vehicles
4. Motor bike

Answer: 2. Bicycle, as it is an eco-friendly and cost-effective mode of transport, which can be used for short distances.

2. Which department advises people to save petrol/diesel while driving?

1. UNESCO
2. Traffic department
3. PCRA
4. NHAI

Answer: 3. PCRA (Petroleum Conservation Research Association) advises people to save petrol/diesel while driving.

List The Major Products Obtained From Petroleum And Their Uses, Class 8

Question 2. The picture shows how petroleum and natural gas are extracted through oil wells

Which of the following statements is supported by the picture?

Circle ‘Yes’ or ‘No’ for the correct response.

Answer:

1. Yes
2. No, gases are lighter than liquids (petroleum)
3. Yes

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2. Which of these conditions is required for the formation of natural gas?

1. Low pressure
2. Presence of air
3. High temperature
4. Presence of water

Answer: 3. High temperature

3. Which of these petroleum products is used for heavy motor vehicles?

1. LPG
2. Diesel
3. Petrol
4. Kerosene

Answer: 2. Diesel

4. What is the advantage of using CNG instead of petrol in light motor vehicles?

1. It can be stored easily
2. It can be extracted easily
3. It causes less air pollution
4. It releases more energy on combustion

Answer: 3. It causes less air pollution.

Question 3. The table shows two groups of natural resources.

1. Which of these statements is true about coal? Circle ‘Yes’ or ‘No’ for the correct response.

Answer:

1. No
2. Yes, coal is formed from plant remains buried deep under the Earth.
3. Yes, the formation of coal requires high temperature and high pressure.

2. Where is a coal reserve most likely to be found?

1. Inside volcanoes
2. Beneath glaciers
3. On the ocean floors
4. Under the land surface

Answer: 4. Under land surfaces

3. Which gas is mainly emitted during the combustion of coal?
Answer: Carbon dioxide

4. Coke is a product obtained by the processing of coal. Which of these is a byproduct of making coke?

1. Coal tar
2. Bitumen
3. Coal gas
4. Kerosene

Answer: 3. Coal gas

5. The material X is a fossil fuel. It is formed from the buried large land plants (vegetation) by a very slow process. When X is heated in the absence of air, it gives three products, A, B, and C.
Answer: A is used in steel making, B is used as an industrial fuel, whereas product C has been traditionally used for metallising the roads. It is now replaced by a petroleum product, bitumen.

CBSE Class 8 Science Chapter 11 Chemical Effects Of Electric Current Multiple Choice Questions

Question 1. Plastic wire is

1. An insulator
2. A conductor
3. Both 1 and 2
4. None of these

Answer: 1. An insulator

Question 2. Electrolytes conduct electricity due to the movement of

1. Electrodes
2. Atoms
3. Electrons
4. Ions

Answer: 4. Ions

Read And Learn More CBSE Class 8 Science Multiple Choice Questions

Question 3. The solution that can conduct electricity is of

1. Pure water
2. Water and acid solution
3. Water and salt solution
4. Both B and C

Answer: 3. Water and salt solution

Question 4. Which one of the following solutions will not conduct electricity?

1. Lemon rice
2. Vinegar
3. Tap water
4. Vegetable oil

Answer: 4. Vegetable oil

Question 5. Boojho and Paheli performed experiments taking similar bulbs and cells but two different solutions A and B as shown in figure.

They found that the bulb in setup A glows more brightly as compared to that of setup B. You would conclude that

1. Higher Current Is Flowing Through The Circuit In Set Up A
2. Higher Current Is Flowing Through The Circuit In Set B
3. Equal Current Is Flowing Through Both The Circuits
4. The Current Flowing Through The Circuits In The Two Setups Cannot Be Compared In This Manner

Answer: 1. Higher Current Is Flowing Through The Circuit In The Setup A

Question 6. Observe the following circuits. In which circuit will the bulb glow? Write ‘Yes’ or ‘ No’ in the blank space provided along with each of the circuits given in the figure.

Answer:

1. No
2. Yes
3. No
4. Yes

Question 7. Observe the figure.

Which of these two circuits, A or B, shows the correct observation? It is not clear from the diagram what A and B.

So cannot predict the actual solution. But if we compare with the activity. This seems to be a potato, and the correct diagram is A because the positive terminal makes the green spot on the potato.

Question 8. 

Which of the following solutions will not make the bulb glow in the figure?

1. Sodium chloride
2. Copper sulphate
3. Silver nitrate
4. Sugar solution in diluted water

Answer: 4. Sugar solution in diluted water

Question 9. The process of depositing a thin layer of any superior metal over an object made of a cheaper metal with the help of electricity is called

1. Electro refining
2. Electro-metallurgy
3. Electroplating
4. None Of the Above

Answer: 3. Electroplating

Question 10. Which of the following metals is used in electroplating to make objects appear shiny?

1. Iron
2. Copper
3. Chromium
4. Aluminium

Answer: 3. Chromium

Question 11. Boojho’s uncle has set up an electroplating factory near his village. He should dispose of the waste of factory waste

1. In the nearby river
2. In the nearby pond
3. In the nearby corn field
4. According to the disposal guidelines of the local authority

Answer: 4. According to the disposal guidelines of the local authority.

Short Answer Type Questions

Question 12. Boojho made the circuit as shown in the figure. He wanted to observe what happens when an electric current is passed through water, but he forgot to add a few drops of lemon juice to the water. Will it make any difference to his observations? Explain

Answer: Adding few drops of lemon juice in water will increase the conductivity of the solution. The current will flow in both the cases but adding of lemon juice makes it easy for the current to flow.

Question 13. Observe the following circuit given in the figure.

Current does not flow in the circuit if there is a gap between the two wires. Does It Indicate that air is a poor conductor of electricity? Does air never conduct electricity? Explain.?
Answer: Yes, current is not flowing through the air gap between the wires, It means that air Is a poor conductor of electricity.

Air conducts electricity only when there is a great voltage or when there is some moisture in the air.

Question 14. Boojho made the circuit given in Figure and observed that the bulb did not glow. On Paholl’s suggestion, he added one more cell in the circuit. The bulb now glows. Explain.

Answer: Initially, the bulb was not glowing because the voltage required to make the bulb glow was not sufficient. When the voltage increases more than a particular value, the bulb starts glowing because it gets sufficient energy to heat its filament.

Question 15. Paheli setup an experiment using liquid A in the beaker as shown in figure. She observed that the bulb glows. Then, she replaced the liquid A by another liquid B. This time the bulb did not glow. Boojho suggested replacing the bulb by an LED. They observed that the LED glows. Explain.

A is a good conductor of electricity, and it allows the maximum current to pass through it, which is sufficient to glow the bulb.

But when it is replaced by another liquid B, the bulb does not glow because liquid B is not a good conductor of electricity. But the small current which is passing through B is sufficient to glow a low-voltage LED, so it glows.