Important Questions Class 8 Science Chapter 15 – Some Natural Phenomena

Important Questions Class 8 Science Chapter 15 – Some Natural Phenomena

The fifteenth chapter of the Class 8th CBSE Science curriculum is about ‘Some Natural Phenomena’. This chapter discusses various events that occur in our nature. Key topics covered in this chapter are: 

• Lightning
• Charging by rubbing
• Different types of charges, their Interaction, and how the transfer of charge happens
• Lightning safety
• Earthquakes and their impact
• Protection against earthquakes

Science is a theoretical subject that requires both studying and practical implementation. At Extramarks, we understand the value of practising important questions to gain mastery in Science. We have created different study resources such as NCERT solutions, chapter-wise notes, CBSE revision notes, etc. to help students with their studies. Students can refer to our question bank Important Questions Class 8 Science Chapter 15 which has been curated by picking questions from various sources such as NCERT textbooks, NCERT exemplar books, other Science reference books, CBSE past years’ question papers, etc. The step-by-step explanations are given for each question help students to revise the chapter fully while solving these questions.  Students can register on the Extramarks website to access our question bank Important Questions Class 8 Science Chapter 15.

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Some Natural Phenomena Class 8 Important Questions with Solutions

Science in secondary school becomes extensive with chapters from Physics, Chemistry and Biology. Students should have a strong grip on the subject as Class 8, 9, 10 will  form the basics  for Class 11 and Class 12 Science. 

One of the key elements to studying Science properly is to practise a lot of questions. Students can confidently rely on our Extramarks question bank Class 8 Science Chapter 15 Important Questions which has been collated by Science faculty members after analysing all past papers and textbook questions. It’s a comprehensive suite of questions which covers the entire Chapter 15. 

Below are a few questions and answers from our question bank of Science Class 8 Chapter 15 Important Questions.

Question 1. What is an electroscope?

Answer 1. An electroscope is a device for detecting and determining the presence of electric charges using electrostatic attraction and repulsion.

Question 2. Define earthing.

Answer 2. The process of transferring the charge from a charged object to the ground or earth is called earthing.

Question 3. What is the primary purpose of providing earthing in buildings?

Answer 3. There may be an accidental leakage of electric current in the buildings. Besides, during monsoons, a live wire can come in contact with the building wall. In such cases, earthing helps divert the current’s path to earth to protect us from an electric shock. Therefore, the primary purpose of providing earthing in buildings is to protect ourselves from electrical shocks due to any electrical current leakage.

Question 4. What happens when a plastic comb rubbed with dry hair attracts small pieces of paper? Explain.

Answer 4. A plastic comb gets electrically charged due to rubbing, & therefore, it attracts small pieces of paper that are neutral, as a charged body can attract an uncharged body.

Question 5. What causes an earthquake?

Answer 5. The tectonic plates are in continuous motion. When they brush with each other, a plate goes under another because of collision, and that causes a disturbance in the earth’s crust. This disturbance is shown up as an earthquake on the earth’s surface. Volcanic eruptions are also a cause of tremors on the earth’s surface.

Question .6. How is an earthquake measured?

Answer 6. The magnitude of an earthquake is measured in terms of a magnitude on a scale known as the Richter scale. Destructive earthquakes have an intensity higher than 7 on the Richter scale.

Question 7. What is a seismograph?

Answer 7. An earthquake produces some waves on the surface of the earth. These waves are called Seismic Waves. These waves are recorded by a device known as the seismograph.

Question 8. What are fault zones?

Answer 8. The movement of tectonic plates causes earthquakes. The boundaries of these plates are the vulnerable zones where earthquakes are more likely to occur. These vulnerable zones are also known as seismic or fault zones.

Question 9. Why can a copper rod not be charged by friction if held by hand?

Answer 9. Copper is a conducting metal, and the electric charge is created on its surface by rubbing with another substance. It flows through our fingers and body into the soil while left uncharged.

Question 10. If a glass rod is rubbed against a silk cloth, the rod

(a) and the cloth both acquire a positive charge.

(b) becomes positively charged while the cloth acquires a negative charge.

(c) and the cloth both get a negative charge.

(d) becomes negatively charged while the cloth gets a positive charge.

Answer 10. The answer is (b) becomes positively charged while the cloth has a negative charge.

Explanation-  When two objects are rubbed, they generate opposite charges. According to the law of convention, it is known that the rod acquires a positive charge(+) and the cloth acquires a negative charge(-).

Question 11. Write T for true and F for false in the following statements-

(a) Like charges attract each other. (T/F)

(b) A charged glass rod gets attracted to a charged plastic straw. (T/F)

(c) Lightning conductors cannot protect a building from lightning. (T/F)

(d) Earthquakes can be predicted in advance. (T/F)

Answer 11. a) False- Unlike charges attract each other while the like charges repel each other.

1. b) True- A charged plastic straw has a negative charge on its surface, while the glass rod has positive charges on its surface. Unlike charges that attract each other, they both attract each other.
2. c) False – When lightning occurs, the atmospheric charges are transferred to the earth directly by a lightning conductor. Therefore the building is protected from lightning.
3. d) False- Even though the earthquake’s causes are known, there are no instruments that are invented to detect them in advance. Therefore earthquakes cannot be predicted in advance.

Question 12. Sometimes, a crackling sound is heard while wearing a sweater during winter. Explain.

Answer 12. When we take out the sweater, the woollen sweater gets charged due to friction between the sweater and the body. This results in a crackling sound.

Question 13. Why does a charged body lose its charge when we touch it with our hand? Explain.

Answer 13. The charges get conducted to the earth by our body when we touch them, and the conductor loses its charge. This phenomenon is known as electric discharge.

Question 14. What is the name of the scale on which the destructive energy of an earthquake is measured? An earthquake measures 3 on this scale. Would a seismograph record it? Is it likely to cause a lot of damage?

Answer 14. The Richter scale is a device used to measure an earthquake’s destructive energy. The scale has a reading range from 1 to 10. A seismograph would record an earthquake measuring 3. The magnitude of a scale up to 3 would not be considered destructive and does not cause much damage. An Earthquake of magnitude 5 is deemed harmful to nature.

Question 15. Suggest three safety measures to protect ourselves from lightning.

Answer 15. There are various ways to protect ourselves from lightning are-

(i) Always remain in a closed place; if you are in a car, stay there until the lightning is over and keep all the windows closed.

(ii) Never touch electrical wires, telephone cables or metal pipes.

(iii) Do not bathe in running water; this may cause an electric shock.

Question 16. Why is a charged balloon repelled by another charged balloon, whereas another charged balloon attracts an uncharged balloon?

Answer 16. The surface charge of the balloons is similar; hence, they get repelled. When a charged balloon is kept close to an uncharged balloon due to the induction of charges, it acquires charges which are opposite to that of a charged balloon. As those charges attract each other, the uncharged balloon gets attracted by the charged balloon.

Question 17. Suppose you are out of your home, and an earthquake occurs. What precautions are to be taken to protect from an earthquake?

Answer 17. The following precautions should be taken when the earthquake strikes-

(a) Find an open field and stay away from buildings, trees, electric wires and poles.

(b) If you are driving a car, then go to an open field and do not come out of your car.

Question 18. The weather forecasting department has predicted that a thunderstorm will likely occur on a day. Suppose you are going out on that day. Would you carry an umbrella? 

Answer 18. No, it is not safe. One should not carry an umbrella when it is a thunderstorm. The thunderstorm occurs along with lightning, and the charges might travel from the cloud to the metal rod of the umbrella and might cause you to have an electric shock if you are carrying it.

 Question 19. Electric current has to be passed from one body to another. For this purpose, the bodies must be joined-

(a) cotton thread.

(b) plastic string.

(c) copper wire

(d) rubber band

Answer 19. The answer is (c) copper wire

Explanation- Copper is a good conductor of electricity. Plastic, rubber and cotton are insulators of electricity.

Question 20. The movement of the earth’s plates causes-

(a) cyclones

(b) lightning

(c) earthquakes

(d) thunderstorms

Answer 20. The answer is (c) earthquakes

Explanation- Earthquakes occur when the earth’s plates brush past one another. Earthquakes can cause damage to buildings and dams.

Question 21. State whether the following statements are True or False-

(a) Earthquakes occur all time all over the world.

(b) The earth’s outer layer plates are always in continuous motion.

(c) Earthquakes on the earth can also be caused by the eruption of a volcano.

(d) The electric discharge process cannot occur between cloud and the earth.

(e) Bathing outside should be avoided during a thunderstorm.

Answer 21.

1. True.
2. True.
3. True.
4. False- The process of electric current discharge occurs between the clouds and the earth.
5. True

Question 22. Is it possible to predict the occurrence of an earthquake?

Answer 22. No, it is impossible to predict the occurrence of an earthquake.

Question 23. What will happen if a charged straw is brought close to another uncharged straw?

Answer 23. The two straws will attract each other

Question 24. Explain how lightning takes place.

Answer 24. During the formation of a thunderstorm, the air currents move upwards while the water drops move downwards. These vigorous movements of air currents cause the separation of charges. The positive charges accumulate near the upper part of the clouds, and the negative charges get near the lower regions. There is an accumulation of positive charge near the ground as well. When the intensity of the accumulated charges becomes large, the air cannot resist the charge flow. As a result, negative & positive charges meet, creating a streak of bright light and sound called lightning and thunder.

Question 25. Mention three safety measures that you will take to protect yourself if an earthquake strikes when you are inside the house.

Answer 25.

• Take the shelter under a table and stay there till the shaking stops.
• Stay away from the tall and heavy objects that can fall on you.
• If you are in lying in bed, do not get up. Protect your head with a pillow.

Question 26. Explain why a wireless telephone is safer than a landline telephone during lightning.

Answer 26. Lightening is a process of electrical discharge. During lightning, electric charge can pass through landline telephone wires which can be dangerous. So, it is comparatively safer to use a wireless phone in place of a landline telephone during Lightning.

Question 27. What precautions would you take when lightning occurs?

Answer 27.

• Stay away from open vehicles, like motorcycles, tractors, construction machinery, etc.
• Do not take shelter in the open fields, tall trees, parks and high places.
• Do not carry an umbrella when lightning strikes.
• Stay away from poles and other metal objects.
• Squat down on the ground. Put your hands on your knees and your head between the hands.

Question 28. If the metal clip used in an electroscope is changed by an ebonite rod and a charged body is brought in touch with it, will there be any effect on the aluminium strips? Explain.

Answer 28. If a metal clip used in the electroscope is changed by an ebonite rod, and when a charged body is kept in touch with it, aluminium strips will show no repulsion. No charge gets transferred to the ebonite rod as it is a bad conductor of electricity.

Question 29. State any two precautions people living in seismic zones should observe to protect against earthquakes.

Answer 29.

1. The buildings in these zones should be made so that they can withstand earthquakes. Modern building technology is making it possible.
2. Mud and timber should be used instead of heavy construction materials. The roof should be kept as light as possible.
3. The cupboards and shelves should be fixed to the walls, so they do not fall easily.

Question 30. What happens when two moving plates of the earth’s crust collide head-on?

Answer 30. When two tectonic plates collide head-on, they push each other up and form mountains. This process created the Himalayas and other great mountain ranges.

Question 31. Why does a charged body loses its charge when we touch it with our hand?

Answer 31. The process of transfer of a charge from a charged body to the earth is called Earthing.

Question 32. Explain how you will charge a ballpoint pen refill by the method of friction.

Answer 32. To charge a ballpoint pen refill, rub it with a wool cloth. It becomes negatively charged.

Question 33. Explain the process of occurrence of lightning.

Answer 33. During a thunderstorm, the air current moves upwards and the water drops move downwards. These movements cause the separation of charges. The positive charge is collected near the upper edges of the clouds, while the negative charge accumulates near the lower edge. There is an accumulation of positive charge near the ground also. When the magnitude of the accumulated charge becomes very large, the air, which is usually a poor conductor of electricity, can no longer resist its flow. Positive and negative charges meet, producing streaks of bright light and sound. We see streaks as lightning. This process is called an electric discharge. The electric discharge method can occur between two or more clouds or between clouds and the earth.

Question 34. Explain the precautions to be taken during lightning or thunderstorms.

Answer 34. Precautions to be taken during lightning or thunderstorms are-

1. to find a safe place indoors- Outdoor places are not safe during Lightning or thunderstorms. A house or building is a safe place. If we travel by car or bus, we are safe inside with the windows and doors of the vehicle closed.
2. Carrying an umbrella is not a good idea during thunderstorms. If you are in a forest, take shelter under shorter trees, not tall ones. If no shelter is available, stay far away from all trees. Stay away from poles or any other metal objects.
3. We should not lie directly on the ground. Instead, squat low on the ground. Place hands on your knees with your head in between your hands. Such a position will make us the smallest target to be affected.
4. Lightning can strike telephone cords, electrical wires and metal pipes inside the house. During a thunderstorm, contact with these must be avoided. It is safer to use mobiles and cordless phones. However, it is not good to call a person who is receiving your phone through a wired phone.
5. Bathing outside should be avoided during thunderstorms to avoid contact with running water.
6. Electrical appliances like computers, television, etc., should be unplugged. Electrical lights can remain on. They do not cause any harm.

Question 35. What are the precautions to be taken during an earthquake?

Answer 35. The following precautions to be taken during an earthquake are-

If you are at home-

1. Take shelter under a table and be there until the shaking stops.
2. Stay away from all the tall and heavy objects because they may fall on you.
3. If you are in a bed, do not get up. Protect your head with a cushion or pillow.

If you are outdoors-

1. Find a clear place, away from buildings, trees and overhead electric lines. 
2. If you travel in a car or a bus, do not come out. Ask the driver to drive slowly to a safe place. Do not come out till the tremors stop.

Benefits of Solving Class 8 Science Chapter 15 Important Questions

Science is a subject that requires constant revision of each chapter. Class 8 students are advised to go through Extramarks Important Questions Class 8 Science Chapter 15 and other chapters question banks. 

While solving these questions students will be forced to revise all concepts again. So they would get to know their strong and weak areas and can accordingly plan for further revision.

Below are some of the benefits of solving questions from our Important Questions Class 8 Science Chapter 15:

• Students get an idea about the best possible ways by which answers can be presented in the exam. The answers given in Important Questions Class 8 Science Chapter 15 are very precise and exam-oriented. By going through these questions students are able to understand their weak and strong points. Based on it they can further improve their weaker sections by revising those topics.
• The questions in our Chapter 15 Class 8 Science Important Questions are collated by referring to various trusted sources, including NCERT textbooks, NCERT exemplar books, CBSE past years’ question papers and other reference books. Our team has carefully chosen questions so that the entire chapter is covered. 
• MCQs, short and medium-format questions and answers and long answer questions are provided with step-by-step solutions to make students well versed with various questions appearing in the CBSE examination. 

Extramarks provides comprehensive learning content for students from Class 1 to Class 12. Along with important questions and answers, we have abundant resources available on our website. Students can check the links given below to access these resources-

• NCERT books
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