HOTS Questions - Some natural phenomena - Class 8 Science

Posted by Olympiad Tester on Mar 23, 2023

HOTS Questions - Some natural phenomena - Class 8 Science

These HOTS questions on 'Some natural phenomena' for Class 8 will test the Higher Order Thinking Skills in Science of CBSE students and NSO Science Olympiad aspirants.

Q1) When a negatively charged glass rod is brought close to a neutral metal sphere, what will happen to the sphere?

a) The sphere will remain neutral
b) The sphere will gain a positive charge
c) The sphere will gain a negative charge
d) The sphere will lose its electrons

Answer: b) The sphere will gain a positive charge due to induction when the negative charge of the glass rod repels the electrons in the metal sphere.

Q2) Two balloons X and Y are rubbed with woolen cloth. When brought near each other, what will happen?

a) The balloons will attract each other
b) The balloons will repel each other
c) The balloons will remain neutral
d) The effect cannot be predicted

Answer: b) The balloons will repel each other due to the buildup of static charge on their surfaces after being rubbed with woolen cloth.

Q3) When a positively charged plastic comb is brought close to a stream of water, what will happen?

a) The water stream will bend towards the comb
b) The water stream will bend away from the comb
c) The water stream will remain unaffected
d) The water stream will break into droplets

Answer: a) The water stream will bend towards the comb due to the attraction between the positively charged comb and the polar water molecules.

Q4) Two identical metal spheres A and B are kept in contact and then separated. What will happen to the charge on each sphere?

a) Sphere A will be negatively charged and Sphere B will be positively charged
b) Sphere A and B will both be negatively charged
c) Sphere A and B will both be positively charged
d) There will be no charge on either sphere

Answer: c) Sphere A and B will both be positively charged due to the redistribution of electrons between them when they are separated.

Q5) When a negatively charged ebonite rod is brought close to a neutral metal can, what will happen to the charge on the can?
a) The can will remain neutral
b) The can will gain a positive charge
c) The can will gain a negative charge
d) The can will lose its electrons

Answer: b) The can will gain a positive charge due to induction when the negative charge of the ebonite rod repels the electrons in the metal can.

Q6) Two pith balls are suspended from the same point by separate threads. When a positively charged glass rod is brought near one of the pith balls, what will happen to the other pith ball?

a) The other pith ball will be attracted towards the glass rod
b) The other pith ball will be repelled by the glass rod
c) The other pith ball will remain stationary
d) The effect cannot be predicted

Answer: b) The other pith ball will be repelled by the glass rod due to the buildup of opposite charges on the two pith balls.

Q7) When a charged plastic rod is brought close to a piece of paper, what will happen?

a) The paper will be attracted towards the rod
b) The paper will be repelled by the rod
c) The paper will remain stationary
d) The effect cannot be predicted

Answer: a) The paper will be attracted towards the rod due to the buildup of opposite charges on the paper and the rod.

Q8) A glass rod is rubbed with a silk cloth and gains a positive charge. If the rod is brought close to an uncharged metal ball, what will happen?

A) The metal ball will become positively charged
B) The metal ball will become negatively charged
C) The metal ball will not become charged
D) The metal ball will be repelled by the rod

Answer: D) The metal ball will be repelled by the rod. This is because the glass rod is positively charged after being rubbed with the silk cloth, and the metal ball is uncharged. When brought close together, the positive charge of the glass rod repels the electrons in the metal ball, causing the ball to be repelled.

Q9) A plastic comb is rubbed with a woolen cloth and gains a negative charge. If the comb is brought close to small pieces of paper, what will happen?

A) The paper pieces will be attracted to the comb
B) The paper pieces will be repelled by the comb
C) The paper pieces will remain stationary
D) It depends on the type of paper

Answer: A) The paper pieces will be attracted to the comb. This is because the plastic comb gains a negative charge after being rubbed with the woolen cloth, and the paper pieces are neutral. When brought close together, the negative charge on the comb attracts the electrons in the paper pieces, causing them to be attracted to the comb.

Q10) Two identical metal spheres are suspended from insulating strings. Sphere A is given a positive charge by touching it with a positively charged rod, while sphere B is left uncharged. What will happen when sphere A is brought close to sphere B?

A) Sphere B will become positively charged
B) Sphere B will become negatively charged
C) Sphere B will remain uncharged
D) Sphere A will become negatively charged

Answer: A) Sphere B will become positively charged. This is because the positive charge on sphere A repels the electrons in sphere B, causing them to move to the far side of sphere B. The near side of sphere B becomes positively charged as a result.

Q11) A metal spoon is charged by bringing it close to a negatively charged balloon. What happens when the charged spoon is brought close to an uncharged metal can?

A) The can becomes negatively charged
B) The can becomes positively charged
C) The can remains uncharged
D) The can is repelled by the spoon

Answer: B) The can becomes positively charged. This is because the negative charge on the spoon repels the electrons in the metal can, causing them to move to the far side of the can. The near side of the can becomes positively charged as a result.

Q12) A plastic ruler is charged by rubbing it with a dry cloth. What happens when the charged ruler is brought close to a stream of water?

A) The water stream becomes positively charged
B) The water stream becomes negatively charged
C) The water stream bends towards the ruler
D) The water stream bends away from the ruler

Answer: D) The water stream bends away from the ruler. This is because the charged ruler repels the electrons in the water, causing them to move away from the ruler. The movement of the electrons creates a slight negative charge in the water, which causes the water stream to be repelled by the ruler.

Q13) Two balloons are charged by rubbing with wool. What will happen when they are brought close to each other?

a) They will attract each other

b) They will repel each other

c) They will remain neutral

d) None of the above

Answer: b) They will repel each other. When two objects are charged with the same type of charge, they will repel each other.

Q14) Two metal spheres X and Y are placed on insulating stands. When X is given a positive charge and Y is grounded, what will happen?

a) X will lose its charge

b) Y will gain a negative charge

c) X will attract Y

d) X will repel Y

Answer: d) X will repel Y. When a charged object is brought near a grounded object, the grounded object becomes charged with the opposite type of charge. Since X has a positive charge, it will repel Y which is now negatively charged.

Q15) A plastic comb is charged by rubbing it with dry hair. What will happen when the comb is brought near small pieces of paper?

a) The paper will be attracted to the comb

b) The paper will be repelled by the comb

c) The paper will remain neutral

d) None of the above

Answer: a) The paper will be attracted to the comb. When an object is charged, it can attract neutral objects like small pieces of paper.

Q16) A positively charged glass rod is brought close to a negatively charged metal ball. What will happen?

a) The glass rod will attract the metal ball

b) The glass rod will repel the metal ball

c) The metal ball will attract the glass rod

d) The metal ball will repel the glass rod

Answer: b) The glass rod will repel the metal ball. Objects with the same type of charge repel each other.

Q17) If a positively charged comb is brought close to a negatively charged straw, what will happen?

Answer: The straw will be attracted towards the comb due to the opposite charges.

Q18) Two metal spheres A and B are placed close to each other without touching. Sphere A is negatively charged while sphere B is positively charged. What will happen?

Answer: The spheres will be attracted towards each other due to the opposite charges.

Q19) A glass rod and a silk cloth are rubbed together. What will happen when the glass rod is brought near some small pieces of paper?

Answer: The paper pieces will be attracted towards the glass rod due to the static charge developed on it.

Q20) Two balloons A and B are inflated and rubbed with a woolen cloth. What will happen when they are brought close to each other?

Answer: The balloons will be repelled from each other due to the same charges developed on them.

Q21) A metal spoon is charged by rubbing it with a woolen cloth. What will happen when the spoon is brought close to a neutral metal can?

Answer: The can will be attracted towards the spoon due to the opposite charges developed on them.

Q22) A negatively charged rod is brought close to a neutral metal ball hanging from a string. What will happen to the metal ball?

Answer: The metal ball will be attracted towards the rod due to the opposite charges developed on them.

Q23) A plastic comb is charged by rubbing it with a dry cloth. What will happen when it is brought close to a stream of water flowing from a tap?

Answer: The water stream will be deflected due to the static charge developed on the comb.

Q24) Two metal spheres A and B are placed close to each other without touching. Sphere A is positively charged while sphere B is negatively charged. What will happen?

Answer: The spheres will be attracted towards each other due to the opposite charges.

Q25) A plastic pen is charged by rubbing it with a woolen cloth. What will happen when it is brought close to a strand of hair?

Answer: The strand of hair will be attracted towards the pen due to the static charge developed on it.

Q26) A negatively charged balloon is brought close to a neutral wall. What will happen to the balloon?

Answer: The balloon will be attracted towards the wall due to the opposite charges developed on them.

HOTS Questions - Some natural phenomena - Earthquakes

Q1) What should you do if you are driving when an earthquake strikes?

a) Speed up and try to outrun the earthquake

b) Pull over to the side of the road and stop

c) Keep driving and try to find a safe place

d) Drive towards the nearest building and take shelter inside

Answer: b) Pull over to the side of the road and stop

Explanation: If you are driving when an earthquake strikes, you should pull over to the side of the road as quickly and safely as possible. Stay in your car and wait for the shaking to stop. Avoid parking under or near bridges, overpasses, buildings, or power lines, as these structures may collapse during an earthquake.

Q2) You are on the 16th floor of a building and feel tremors, what should you do?

a) Run down the stairs as fast as possible

b) Stay where you are and wait for the tremors to stop

c) Wait for the elevator and take it down

d) Open the window and shout for help

Answer: b) Stay where you are and wait for the tremors to stop

Explanation: In the event of an earthquake, it is not safe to use the elevators as they could get stuck or malfunction. Running down the stairs can also be dangerous, as it may cause panic and injuries. It is safer to stay where you are and wait for the tremors to stop. Once the shaking stops, you should evacuate the building using the stairs.

Q3) You are in a crowded mall when an earthquake strikes. What should you do?

a) Try to push your way through the crowd to reach the exit

b) Look for a sturdy object to hold on to and stay in place

c) Shout for help and try to find a place to hide

d) Run in the direction of the nearest exit as fast as possible

Answer: b) Look for a sturdy object to hold on to and stay in place

Explanation: In a crowded area such as a mall, it may not be possible to evacuate the building immediately. If an earthquake strikes, look for a sturdy object such as a table, desk, or pillar to hold on to and protect your head and neck. Stay where you are until the shaking stops, then evacuate the building using the stairs.

Q4) What should you do if you are inside a store when an earthquake strikes?

a) Run outside as quickly as possible

b) Hide under a table or desk

c) Stand in the doorway

d) Keep shopping and ignore the shaking

Answer: b) Hide under a table or desk

Explanation: If you are inside a store when an earthquake strikes, you should quickly take cover under a sturdy piece of furniture, such as a table or desk, and hold on until the shaking stops. Avoid standing near windows, shelves, or heavy objects that could fall and cause injury.

Q5) What should you do if you are on the beach and feel an earthquake?

a) Run towards the water and dive in

b) Stay on the beach and wait for the earthquake to stop

c) Move to higher ground immediately

d) Keep walking along the beach to a safer location

Answer: c) Move to higher ground immediately

Explanation: If you are on the beach and feel an earthquake, move to higher ground immediately. Earthquakes can trigger tsunamis that can cause large waves and flooding. The safest place to be during a tsunami is on higher ground or inland, away from the coast.

Q6) You are in a grocery store during an earthquake. What is the safest thing to do?

a) Run outside as quickly as possible

b) Get under a table or other sturdy furniture

c) Hide in the aisles among the shelves

d) Go to the front of the store and wait for the earthquake to stop

Answer: b) Get under a table or other sturdy furniture

Explanation: If you are in a grocery store during an earthquake, you should quickly get under a table or other sturdy furniture and hold on until the shaking stops. Avoid standing near windows, heavy objects, or hanging items that may fall and cause injury.

Q7) You are in a multi-story building during an earthquake. What should you do if you cannot get out of the building?

a) Run to the nearest exit and try to get out

b) Stay in the stairwell and wait for the earthquake to stop

c) Get under a desk or table and hold on until the shaking stops

d) Climb out of the window and down the side of the building

Answer: c) Get under a desk or table and hold on until the shaking stops

Explanation: If you cannot get out of a multi-story building during an earthquake, you should quickly get under a desk or table and hold on until the shaking stops. Stay away from windows and avoid using elevators.

Q8) What should you do if you are outside during an earthquake?

a) Run towards the nearest building and take shelter inside

b) Stand near trees or buildings for protection

c) Lie flat on the ground and cover your head and neck

d) Keep walking to a safer location

Answer: c) Lie flat on the ground and cover your head and neck

Explanation: If you are outside during an earthquake, move away from buildings, trees, and power lines. Lie flat on the ground, cover your head and neck with your hands, and stay in that position until the shaking stops. If you are in a crowded area, try to move to an open space where you are less likely to be injured by falling objects.

Q9) What is the name of the scale used to measure the magnitude of an earthquake?

a) The Richter Scale

b) The Seismometer Scale

c) The Tectonic Scale

d) The Earthquake Magnitude Scale

Answer: a) The Richter Scale

Explanation: The Richter Scale is a scale used to measure the magnitude of an earthquake. This scale measures the amount of energy released by an earthquake at its epicenter. The higher the number on the scale, the greater the magnitude of the earthquake.

Q10) What should you do if you are trapped under rubble after an earthquake?

a) Yell for help and try to move around to free yourself

b) Stay still and wait for rescuers to find you

c) Use your phone to call for help

d) Start digging your way out with your bare hands

Answer: b) Stay still and wait for rescuers to find you

Explanation: If you are trapped under rubble after an earthquake, stay still and wait for rescuers to find you. Yelling or moving around can cause more debris to fall and make it harder for rescuers to find you. Cover your mouth with a cloth or clothing to avoid breathing in dust and debris. Use a phone, whistle, or other noise-making device to alert rescuers to your location.

Q11) What is the name of the point within the Earth's crust where an earthquake originates?

a) The Hypocenter

b) The Epicenter

c) The Seismometer

d) The Tectonic Plate

Answer: a) The Hypocenter

Explanation: The hypocenter, also known as the focus, is the point within the Earth's crust where an earthquake originates. The epicenter is the point on the Earth's surface directly above the hypocenter.

Q12) What is the name of the phenomenon where soil and rocks turn into a liquid-like state during an earthquake?

a) Liquefaction

b) Subsidence

c) Landslides

d) Seiche

Answer: a) Liquefaction

Explanation: Liquefaction is the phenomenon where soil and rocks turn into a liquid-like state during an earthquake. This can cause buildings and other structures to sink or tilt, and can also result in landslides and other types of ground movement.

Q13) What is the name of the earthquake that occurred in Japan in 2011 and caused a devastating tsunami?

a) The Sumatra Earthquake

b) The Haiti Earthquake

c) The Chile Earthquake

d) The Tohoku Earthquake

Answer: d) The Tohoku Earthquake

Explanation: The Tohoku Earthquake, also known as the Great East Japan Earthquake, occurred in Japan in 2011 and caused a devastating tsunami that killed thousands of people and caused extensive damage to coastal communities.

Q14) What is the name of the system that is used to issue warnings for potential tsunamis?

a) The Seismometer System

b) The Tsunami Warning System

c) The Earthquake Warning System

d) The Seismic Alert System

Answer: b) The Tsunami Warning System

Explanation: The Tsunami Warning System is a system that is used to issue warnings for potential tsunamis. This system uses a network of sensors to detect earthquakes and other events that could cause a tsunami, and issues alerts and warnings to potentially affected areas.

Q15) What is the name of the earthquake-resistant building design that originated in Japan?

a) The Richter Design

b) The Tectonic Design

c) The Seismic Design

d) The Tsunami Design

Answer: c) The Seismic Design

Explanation: The Seismic Design is an earthquake-resistant building design that originated in Japan. This design incorporates special features and materials that are intended to withstand the forces of earthquakes and minimize damage and injuries.

Q16) What is the name of the phenomenon where soil loses its strength during an earthquake?

a) Landslide

b) Soil liquefaction

c) Mudflow

d) Rockfall

Answer: b) Soil liquefaction

Explanation: Soil liquefaction is a phenomenon where soil loses its strength during an earthquake, causing it to behave like a liquid. This can lead to buildings and other structures sinking or tilting, and can increase the likelihood of landslides and other hazards.

Q17) What should you do if you are on a boat during an earthquake?

a) Jump overboard and swim to shore

b) Stay on the boat and wait for the earthquake to stop

c) Move the boat away from the shore as quickly as possible

d) Secure the boat and move to a safe location on land

Answer: d) Secure the boat and move to a safe location on land

Explanation: If you are on a boat during an earthquake, secure the boat and move to a safe location on land as quickly and safely as possible. Tsunamis and large waves can occur during earthquakes, and it is important to move to higher ground or inland, away from the coast.

Q18) What is the name of the boundary where two tectonic plates move apart?

a) Transform boundary

b) Convergent boundary

c) Divergent boundary

d) Subduction zone

Answer: c) Divergent boundary

Explanation: A divergent boundary is a boundary where two tectonic plates move apart from each other. This can lead to the formation of new oceanic crust and volcanic activity, as well as earthquakes.

HOTS Questions - Some natural phenomena - Earthing

1. In an electrical circuit, which wire is connected to the earth?

(a) The live wire

(b) The neutral wire

(d) None of the above

Answer: (c) The earthing wire. The earthing wire is connected to the earth in order to prevent electric shocks and to ensure the safe operation of electrical appliances.

2. In an experiment to demonstrate the need for earthing, what happens when an un-earthed metal plate is brought near a positively charged plastic rod?

(a) Nothing happens

(b) The metal plate becomes positively charged

(d) The metal plate gets repelled by the plastic rod

Answer: (c) The metal plate becomes negatively charged. When an un-earthed metal object is brought near a charged object, it can become charged by induction. In this case, the positively charged plastic rod induces a negative charge on the metal plate.

3. In which of the following situations is earthing not required?

(a) When using an electric iron

(b) When using a washing machine

(d) When using an electric stove

Answer: (c) When using a TV. Earthing is necessary in situations where there is a possibility of electric shock, such as when using electrical appliances in wet areas or when using appliances with metallic bodies.

4. What is the purpose of the third (earth) wire in a three-pin plug?

(a) To provide a return path for current

(b) To provide a connection to the live wire

(d) To provide a connection to the earth

Answer: (d) To provide a connection to the earth. The earth wire in a three-pin plug is connected to the metal body of the appliance and to the earth, in order to prevent electric shocks and to ensure the safe operation of electrical appliances.

5. In an electrical circuit, what is the role of the fuse?

(a) To provide a return path for current

(b) To prevent short circuits

(d) To limit the amount of current that flows through the circuit

Answer: (d) To limit the amount of current that flows through the circuit. The fuse is designed to break the circuit if the current exceeds a certain level, in order to prevent damage to electrical appliances and to prevent fires.

6. Which of the following is the most important reason for earthing electrical appliances?

(a) To prevent electric shock

(b) To prevent short circuits

(d) To prevent fires

Answer: (a) To prevent electric shock. Earthing ensures that any leakage of current from electrical appliances gets directed to the earth, thereby preventing electric shocks.

7. In which of the following situations is earthing not necessary?

(a) When using an electric heater in a bathroom

(b) When using a hairdryer in a salon

(d) When using a computer in an office

Answer: (d) When using a computer in an office. Earthing is necessary in situations where there is a possibility of electric shock, such as when using electrical appliances in wet areas like bathrooms or salons, or when using appliances with metallic bodies like microwave ovens.

8. In an experiment to demonstrate the need for earthing, what happens when an un-earthed metal plate is brought near a negatively charged plastic rod?

(a) Nothing happens

(b) The metal plate becomes positively charged

(d) The metal plate gets attracted towards the plastic rod

Answer: (b) The metal plate becomes positively charged. When an un-earthed metal object is brought near a charged object, it can become charged by induction. In this case, the negatively charged plastic rod induces a positive charge on the metal plate.

9. A person touches a metal appliance that is not earthed and receives an electric shock. What is the most likely reason for this?

(a) The person has a high body resistance

(b) The metal appliance is not properly insulated

(d) The metal appliance has a leakage of current

Answer: (d) The metal appliance has a leakage of current. When an electrical appliance is not properly earthed, any leakage of current from the appliance can flow through the person touching the appliance, resulting in an electric shock.

10. In an experiment to demonstrate the need for earthing, what happens when an earthed metal plate is brought near a negatively charged plastic rod?

(a) Nothing happens

(b) The metal plate becomes positively charged

(d) The metal plate gets repelled by the plastic rod

Answer: (a) Nothing happens. When an earthed metal object is brought near a charged object, the excess charge on the object gets neutralized by the earth, and no further charging or discharging takes place.

HOTS Questions - Some natural phenomena - Lightning

1. What is lightning?

a) A flow of electric charge between two charged surfaces

b) A discharge of static electricity in the atmosphere

c) A spark caused by friction between two surfaces

d) A sudden increase in air pressure caused by heat

Answer: b) A discharge of static electricity in the atmosphere

Explanation: Lightning is a natural electrical discharge of static electricity in the atmosphere.

2. What causes lightning to occur?

a) The movement of ocean currents

b) The rotation of the Earth

c) The discharge of static electricity in the atmosphere

d) The melting of ice in the atmosphere

Answer: c) The discharge of static electricity in the atmosphere

Explanation: Lightning occurs when there is a buildup of static electricity in the atmosphere that is discharged in the form of a bolt of lightning.

3. What is thunder?

a) The sound produced by the vibration of air molecules after lightning

b) The flash of light produced by a discharge of static electricity

c) The sound produced by the vibration of the Earth's crust during an earthquake

d) The movement of air caused by the heating and cooling of the Earth's surface

Answer: a) The sound produced by the vibration of air molecules after lightning

Explanation: Thunder is the sound produced by the vibration of air molecules after lightning has passed through the air.

4. Which of the following is not a safety precaution to take during a thunderstorm?

a) Stay indoors and away from windows

b) Avoid using electronic devices or appliances

c) Stay away from water, including swimming pools and showers

d) Stand under a tall tree for protection

Answer: d) Stand under a tall tree for protection

Explanation: Standing under a tall tree during a thunderstorm can be dangerous as it increases the risk of being struck by lightning.

HOTS Questions - Some natural phenomena - Online test

Revision notes - Class 8 Science - Some natural phenomena

Natural phenomena like lightning and earthquakes can be explained using scientific principles. In this chapter, we will learn about the different ways that objects become charged and how charges interact with each other. We will also explore the process of lightning and how to stay safe during a thunderstorm. Finally, we will look at the causes of earthquakes and ways to protect ourselves from their devastating effects.

Static Charges and Methods of Charging:

A body can be charged by rubbing due to friction or by induction. The electrical charges produced by rubbing are called static charges. When objects like plastic get rubbed with hair, they acquire a charge. Similarly, a glass rod gets charged when rubbed with a silk cloth. Like charges repel, while unlike charges attract. Objects that carry a charge by means of rubbing or other processes are called charged objects. Charges can be transferred through good conductors (metals) to another conducting material.

Electroscope and Discharged Objects:

A device that can detect the presence of charge is called an electroscope. When objects lose their charge by transfer, they are known as discharged objects.

Earthing:

The process of transferring charges from a charged object to the earth is called earthing.

Lightning:

During thunderstorms, air currents move upwards and water droplets move downwards. This causes separation of charges between clouds and between clouds and earth. When the magnitude of charges increases, air (normally a bad conductor) starts conducting and allows the flow of electricity. This is called lightning, as this flow of charge is accompanied by bright streaks of light and sound. The process of flow of charge from cloud to cloud or from cloud to earth due to the separation of positive and negative charges is called an electric discharge. Lightning conductors help to protect buildings during lightning.

Lightning Safety:

To stay safe during lightning, find a safe place or shelter under small trees, stay inside a car or vehicle with doors and windows shut, and avoid lying on the ground. Inside the house, avoid contact with telephone and electrical wires, avoid bathing, and unplug electrical appliances.

Earthquakes:

Earthquakes are caused due to movement or collision of tectonic plates in the uppermost layer of the earth’s crust. Boundaries of the plates on the earth’s crust are weak zones where earthquakes are most likely to occur. The power of an earthquake is expressed in terms of magnitude on a scale called the Richter scale. An earthquake with magnitude > 7 on the Richter scale is considered destructive. Seismic waves are produced by tremors deep inside the earth. An instrument that records seismic waves is called a seismograph.

Protection from Earthquakes:

To protect yourself from earthquakes, find a clear spot outdoors away from overhead lines and buildings or stay under a table indoors until the tremors stop. In highly seismic areas, build mud houses with light roofs in order to minimize damage, fix cupboards and shelves to walls, and ensure proper working firefighting equipment.

← Older Post Newer Post →