MCQ Questions for Class 8 Science: Ch 16 Light

1. Beam of light striking the reflecting surface is called

(a) reflecting ray

(b) incident ray

(c) refracted ray

(d) normal ray

► (b) incident ray

2. What makes objects visible?

(a) The absorption of light by objects

(b) The reflected light from the object

(c) The total internal reflection taking place in an object

(d) The refracted light from the object

► (b) The reflected light from the object

3. If the angle of incidence is 50°, then calculate the angle between the incident ray and the reflected ray.

(a) 50°

(b) 100°

(c) 130°

(d) 80°

► (b) 100°

4. _________ refers to collection of rays.

(a) Photon

(b) Beam

(c) Shadow

(d) Image

► (b) Beam

5. Which of the following travels faster?

(a) Jet Aero plane

(b) Sound

(c) Light

(d) Supersonic plane

► (c) Light

6. What makes the object visible?

(a) Size

(b) Time

(c) Colour

(d) Light

► (d) Light

7. An example of luminous object is

(a) Star

(b) Smooth surface

(c) Mirror

(d) Cloth

► (a) Star

8. With what is glass coated in order to convert it into a mirror?

(a) Silver

(b) Copper

(c) Aluminium

(d) Platinum

► (a) Silver

9. In a periscope, how are the reflecting mirrors arranged?

(a) Perpendicular to each other

(b) Parallel to each other

(c) At an angle of 90°

(d) At an angle of 60°

10. How many images are obtained when plane mirrors are arranged parallel to each other?

(a) A single image

(b) Two images

(c) Infinite number of images

(d) Zero image

► (c) Infinite number of images

11. Angle of incidence is always

(a) Equal to angle of reflection

(b) Equal to angle of refraction

(c) More than angle of reflection

(d) Less than angle of reflection

► (a) Equal to angle of reflection

12. Which of the following is used by E.N.T. doctors?

(a) Convex mirror

(b) Convex lens

(c) Plane mirror

(d) Concave mirror

► (d) Concave mirror

13. What is the phenomenon of light bouncing back into the same medium called?

(a) Reflection

(b) Refraction

(c) Dispersion

(d) Splitting

► (a) Reflection

14. What is the nature of image formed on the retina of human eye of an object?

(a) Virtual and erect

(b) Virtual and inverted

(c) Real and erect

(d) Real and inverted

► (d) Real and inverted

15. Convex lens focus a real, point sized image at focus, the object is placed         

(a) At focus

(b) Between F and 2F

(c) At infinity

(d) At 2F

► (c) At infinity         

16. Braille system is used by

(a) Hearing impaired

(b) Black people

(c) Blind people

(d) African people

► (c) Blind people

17. Speed of light is fastest in

(a) Air

(b) Water

(c) Diamond

(d) Glass

► (a) Air

18. Splitting of white rays of light into seven colours is called

(a) Dispersion of light

(b) Reflection of light

(c) Refraction of light

(d) Scattering of light

► (a) Dispersion of light

19. A number of rays from different direction assemble at point are called

(a) Intersecting rays

(b) Parallel rays

(c) Divergent rays

(d) Convergent rays

► (d) Convergent rays

20. What is the name of object through which light can pass?

(a) Opaque

(b) Translucent

(c) Transparent

(d) Luminous

► (c) Transparent

21. The image formed by plane mirror is

(a) real and inverted

(b) real and erect

(c) virtual and inverted

(d) virtual and erect

► (d) virtual and erect

22. The process of banding of seven colours is called

(a) dispersion

(b) spectrum

(c) reflection

(d) normal

► (a) dispersion

23. From a source light travels as rays which are

(a) Divergent

(b) Convergent

(c) Parallel

(d) Diffused

► (c) Parallel

24. What happens in lateral inversion?

(a) The right side of the object will be on the right side of the image.

(b) The left side of the object will be on the left side of the image.

(c) The top of the object will be the bottom of the object.

(d) The right side of the object will be on the left side of the image.

► (d) The right side of the object will be on the left side of the image.

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

(a) Sometimes

(b) Always

(c) Never

(d) Under special case

► (b) Always

Class 8 Science Chapter 16 Extra Questions and Answers Light

Extra Questions for Class 8 Science Chapter 16 Light with Answers Solutions

Light Class 8 Extra Questions Very Short Answer Type

Question 1.
Why fingers appear blurred when we move our hand very fast in front of our eyes?
Answer:
This is due to persistence of vision 1/16th of a second.

Question 2.
What makes things visible?
Answer:
When light reaches our eyes after striking an object, we are able to see an object.

Question 3.
Which element is used at the back of plane mirror?
Answer:
Silver

Question 4.
The distance between the object and its image formed by a plane mirror appears to be 18 cm. What is the distance between mirror and the object?
Answer:
9 cm

Question 5.
How is hypermetropia corrected?
Answer:
It is corrected by using convex lens.

Question 6.
How is myopia corrected?
Answer:
It is corrected by using concave lens.

Question 7.
A ray of light is incident on a mirror at an angle of 40°. What is the angle of reflection ?
Answer:
40°

Question 8.
Name a device which works on the principle of multiple reflection.
Answer:
Periscope

Question 9.
Can we see an object in the dark?
Answer:
No

Question 10.
What is the nature of the image formed by the plane mirror?
Answer:
Virtual and erect

Question 11.
Where is the image formed in a plane mirror?
Answer:
Behind the mirror

Question 12.
The angle between the incident ray and reflected ray is 100°. What is the value of angle of incidence?
Answer:

Question 13.
What is yellow spot?
Answer:
It is highly light sensitive spot for seeing things with highest clearness.

Question 14.
Give an example of night bird.
Answer:
Owl

Question 15.
What do we call the image that cannot be obtained on a screen?
Answer:
Virtual

Question 16.
Show mathematically, the first law of reflection.
Answer:
∠i = ∠r

Question 17.
Name the phenomenon shown in the figure.
Answer:
Lateral inversion.

Question 18.
Express the mathematical formula to calculate the number of images formed when two mirrors are inclined at θ angle. 360°
Answer:
Number of images

Question 19.
How many colours are there in a spectrum of white light?
Answer:
Seven

Question 20.
Name the scientist who studied that if a white light is passed through a prism, it splits into different colours.
Answer:
Sir Issac Newton

Question 21.
Name the spot inside the human eye where the image is not visible.
Answer:
Blind spot

Question 22.
Name the liquid found between the cornea and lens.
Answer:
Aqueous humour

Question 23.
Name the liquid found between the lens and the retina.
Answer:
Vitreous humour

Question 24.
Define the incident ray.
Answer:
The ray of light striking the surface is called an incident ray.

Question 25.
Define angle of reflection.
Answer:
The angle between the reflected ray and the normal is called the angle of reflection.

Light Class 8 Extra Questions Short Answer Type

Question 1.
Define light.
Answer:
Light is defined as a form of energy that stimulates sight and makes things visible.

Question 2.
What is reflection?
Answer:
The bouncing back of light into the same medium after it falls on a surface is called reflection.

Question 3.
What is a mirror?
Answer:
A piece of glass with a shiny metal-covered at back, that reflects light, producing an image of the object in front of it is known as mirror.

Question 4.
State the two laws of reflection.
Answer:
The two laws of reflection are:

• The angle of incidence is always equal to the angle of reflection.
• The incident ray, the reflected ray and normal all lie in the same plane.

Question 5.
How do we see various objects?
Answer:
We see various objects due to reflection. As we know all surface reflect light, when light falls on any object, it reflects the light. The reflected light reaches our eyes and we are able to see the object.

Question 6.
What do you mean by reflected ray?
Answer:
The ray of light which is returned back into the same medium after the incident ray strikes the surface ’ is called reflected ray.

Question 7.
What is irregular reflection?
Answer:
Irregular reflection is defined as the reflection of light from an uneven surface. In irregular reflection, the reflected beam is not parallel.

Question 8.
List the characteristics of an image formed in a plane mirror.
Answer:
The characteristics of an image formed in a plane mirror are:

• It is virtual.
• It is erect.
• It is of same size as the object.

Question 9.
What is lateral inversion?
Answer:
The phenomenon of changing left side to right and right side to left by the mirror while forming image is called lateral inversion.

Question 10.
What is the far point and near point of the human eye with normal vision?
Answer:
In optics, the farthest and closest point at which an object can be brought into focus by the eye are called far point and near point of the eye respectively. The far point of the human eye with normal vision is infinity. The near point of the human eye with normal vision is 25 cm.

Question 11.
What is aqueous humour?
Answer:
The space between the cornea and lens is filled with a liquid called the aqueous humour.

Question 12.
Differentiate between rod and cone cells.
Answer:
Rods are the rod-shaped cells present in the retina of an eye which are sensitive to dim light whereas cones are the cone-shaped cells present in the retina of the eye which are sensitive to bright light.

Light Class 8 Extra Questions Long Answer Type

Question 1.
Write a short note on Braille system.
Answer:
The most popular resource for visually challenged persons is Braille. Braille system was developed by Louis Braille. He himself was a visually challenged person. There is Braille code for common languages, mathematics and scientific notation. Many Indian languages can be read using the Braille system.

Braille system has 63 dot patterns or characters. Each character represents a letter, a combination of letters, a common word or a grammatical sign. Dots are arranged in cells of two vertical rows of three dots each. Patterns of dots to represent some English letters and some common words are shown in Fig. 16.26.

These patterns when embossed on Braille sheets help visually challenged persons to recognise words by touching. To make them easier to touch, the dots are raised slightly. Visually challenged people learn the Braille system by beginning with letters, then special characters and letter combinations. Methods depend upon recognition by touching. Each character has to be memorised. Braille texts can be produced by hand or by machine. Typewriter-like devices and printing machines have now been developed.

Question 2.
Explain the phenomenon of dispersion of light.
Answer:
Dispersion is defined as the phenomenon of splitting of white light into different colours on passing through a transparent medium such as prism. When white light is passed through a prism, it splits into seven colours. It is observed that the colours are in the following order:
Violet (V), Indigo (I), Blue (B), Green (G), Yellow (Y), Orange (O) and Red (R). The order of colours can be remembered by the acronym VIBGYOR. This coloured band is called spectrum of white light.

Question 3.
Write a note on ‘The Human Eye’
Answer:
Eye is a sense organ that enables us to see the world around us. It is roughly spherical in shape

• The first part that is bulged outward is called ‘cornea. It protects the eye.
• Behind the cornea, the coloured part of the eye, iris is present. It controls the size of the pupil.
• Pupil is a small opening in the cornea which allows the light to enter the eye.
• Behind the iris, eye lens is present which is a convex lens. It focus the image on retina, by bending the light rays.
• Retina is the inner back surface of the eye which acts as a screen to form image. It is sensitive to light.
• The sensation of the image formed on the retina is carried to the brain by the optic nerve.
• Optic nerve is connection between the eye and the

Question 4.
Write the ways to protect your eyes.
Answer:
Eyes are very delicate organ that enable us to see this colourful world. Thus, we must protect our eyes and take proper care of them.
Following are the ways to protect the eye:

• Always sit straight while reading or writing.
• Never read while walking or lying down.
• Wash your eyes frequently with clean water.
• Never read in the dim or too much bright light.
• Never rub your eyes with hands.
• Never bring the book too close to your eyes.
• Eat foods rich in vitamin A.

Question 5.
Explain some common eye defects in human.
Answer:
Some eye diseases are:
(i) Cataract: A cataract is a clouding of the lens in the eye leading to a decrease in vision. It can affect one or both eyes. Often it develops slowly. Symptoms may include faded colours, blurry vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognising faces. Cataracts are the cause of half of blindness and 33% of visual impairment worldwide. Cataract is treated by replacing the opaque lens with a new artificial lens.

(ii) Myopia: Near-sightedness or myopia, is the most common refractive error of the eye. Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. It can be corrected using spectacles made of concave lens.

(iii) Hypermetropia: Hypermetropia or long-sightedness occurs when eyeball is too short or the cornea or crystalline lens does not refract the light enough. This lead to formation of the image of a nearby object behind the retina. A hypermetropic person may have blurred vision when looking at objects close to them, and clearer vision when looking at objects in the distance. By placing a convex (plus powered) lens in front of a hypermetropic eye, the image is moved forward and focuses correctly on the retina.

(iv) Astigmatism: It is a defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus. It can be corrected by using a convex lens or concave lens or both.

MCQ Questions for Class 8 Science: Ch 15 Some Natural Phenomena

1. The power of an earthquake is expressed on a scale called

(a) seismic scale

(b) iron scale

(c) richter scale

(d) large scale

► (c) richter scale

2. The shaking of earth is called:

(a) tsunami

(b) volcano

(c) earthquake

(d) all of these.

► (c) earthquake

3. Static electricity charges can be produced by

(a) Heating

(b) Rubbing

(c) Beating

(d) none of these

► (b) Rubbing

4. Why is a lightning conductor installed on a building?

(a) So that it collects the electric power present in the lightning

(b) So that it repels the lightning that falls on the building

(c) So that it forces the lightning to fall in an area where there are no buildings

(d) So that it conducts electric charge to the ground when lightning strikes the building

► (d) So that it conducts electric charge to the ground when lightning strikes the building

5. Which of the following allows the transfer of electric charge from one charged object to another?

(a) Vacuum

(b) Air

(c) Insulator

(d) Conductor

► (d) Conductor

6. Sparks can be seen on an electric pole when wires become

(a) loose

(b) tight

(c) wrinkle

(d) none

► (a) loose

7. What happens when an ebonite rod rubbed with fur and a glass rod rubbed with silk are brought near each other?

(a) They attract each other.

(b) They repel each other.

(c) Nothing happens to them.

(d) They acquire heat.

► (a) They attract each other.

8. Which of the following is not a natural phenomenon?

(a) Cyclone

(b) Lightening

(c) Cooking

(d) Earthquake

► (c) Cooking

9. Which layer of the earth is exposed to the atmosphere?

(a) Outer core

(b) Mantle

(c) Inner core

(d) Crust

► (d) Crust

10. The like charges:

(a) repel each other

(b) attract each other

(c) no interaction takes place

(d) all of these

► (a) repel each other

11. The outermost layer of earth is called

(a) Mountain

(b) Core

(c) Crust 

(d) Mantle

► (c) Crust 

12. The process of transferring a charge from a charged body to the earth is called

(a) Hydrolysis

(b) Electrolysis

(c) Earthing

(d) Discharging

► (c) Earthing

13. The resin which produces spark is

(a) gum

(b) amber

(c) both (a) and (b)

(d) none of these

► (b) amber

14. Which of the following state India is not likely to be affected by earthquake?

(a) Rajasthan

(b) Uttar Pradesh

(c) Jammu Kashmir

(d) Gujarat

► (b) Uttar Pradesh

15. Earthquakes are caused by the

(a) Tilting of earth axis

(b) Movement of water inside

(c) High pollution level

(d) Movement of earth plates

► (d) Movement of earth plates

16. Lightening conductor is made up of

(a) Metal

(b) Cotton

(c) Non-metal

(d) Wooden

► (a) Metal

17. Lightening is _________ on huge scale.

(a) Magnetic effect

(b) Electric spark

(c) Electro-magnetic effect

(d) Heating effect

► (b) Electric spark

18. When you touch a charged body, the charge flows through you into the earth. What is this called?

(a) Induction

(b) Conduction

(c) Capacitance

(d) Earthing

► (d) Earthing

19. What is the purpose of an electroscope?

(a) To detect and test small electric charges

(b) To calculate the amount of electric charge flowing through the conductor

(c) To find out the presence of antimatter

(d) To test the presence of magnetic field

► (a) To detect and test small electric charges

20. The boundaries of earth

(a) Fault zones

(b) Poor zone

(c) Volatile zone

(d) Default zone

► (a) Fault zones

21. The earth’s plate responsible for causing earthquakes is

(a) The inner core of the earth

(b) The mantle of the earth

(c) The crust of the earth

(d) The outer core of the earth

► (c) The crust of the earth

22. Suppose you are in a car and there is a thunderstorm. Which of the following is the best way to protect yourself from possible harm?

(a) Remaining in the car

(b) Getting out of the car and taking cover under the car

(c) Running to a nearby tree

(d) Getting out and standing under an electric pole

► (a) Remaining in the car

23. Lightning occurred when two charges meet they are

(a) both positive

(b) both negative

(c) one positive and other negative

(d) none

► (c) one positive and other negative

24. Building can be protected from lightning by using

(a) Lightning rod on the levels of building

(b) Wooden logs at the top of building

(c) Lightning rod at the top of building

(d) All of these

► (c) Lightning rod at the top of building

25. Interaction of charges is called:

(a) lightning

(b) electrical discharge

(c) earthquake

(d) earthing

► (a) lightning

Class 8 Science Chapter 15 Extra Questions and Answers Some Natural Phenomena

Extra Questions for Class 8 Science Chapter 15 Some Natural Phenomena with Answers Solutions

Some Natural Phenomena Class 8 Extra Questions Very Short Answer Type

Question 1.
What are the two natural calamities?
Answer:

• Lightning and
• Earthquake.

Question 2.
Name other natural calamities except lightning and earthquake.
Answer:
Winds, storms and cyclones.

Question 3.
Name the two types of charges.
Answer:

• Positive; and
• Negative.

Question 4.
Mention the interactions of two types of charges.
Answer:
Like charges repel each other while unlike charges attract each other.

Question 5.
Name the device used to protect buildings from lightning.
Answer:
Lightning conductor.

Question 6.
In which direction does the shock waves produced by an earthquake travel?
Answer:
Both on the surface and inside the earth.

Question 7.
What happens when two clouds with unlike charges approach each other?
Answer:
Lightning strikes

Question 8.
Who discovered the static electricity or lightning in clouds and when?
Answer:
Benjamin Franklin in 1752.

Question 9.
What actually causes lightning?
Answer:
Lightning is caused by the accumulation of charges in the clouds.

Question 10.
What happens when amber is rubbed with fur?
Answer:
It develops the capacity to attract light objects.

Question 11.
What is static electricity?
Answer:
The electrical charge reproduced by rubbing two objects is called static electricity.

Question 12.
What happens when a glass rod and silk cloth are rubbed with each other?
Answer:
The glass rod gets positively charged and silk cloth negatively charged.

Question 13.
What is lightning?
Answer:
Lightning is&an electric spark on huge scale.

Question 14.
What are weak zones called?
Answer:
Seismic or fault zones.

Question 15.
How are most earthquakes caused?
Answer:
Most earthquakes are caused by the movement of earth’s plates.

Question 16.
What is a plate?
Answer:
Each fragment of the outermost layer of the earth is called plate.

Question 17.
What is the uppermost layer of the earth called?
Answer:
Crust

Question 18.
How is an earthquake caused?
Answer:
It is caused by a disturbance deep inside the earth’s crust.

Question 19.
What are seismic waves?
Answer:
Waves produced on the Earth’s surface because of tremors.

Question 20.
When and where a major tsunami took place in India?
Answer:
It occurred in the Indian ocean on 26th December 2004.

Question 21.
What are the natural calamities caused by earthquakes?
Answer:
Earthquakes can cause floods, landslides and tsunamis.

Question 22.
Which kind of material is used to transfer charges from one body to another?
Answer:
Metal conductor

Some Natural Phenomena Class 8 Extra Questions Short Answer Type

Question 1.
What is lightning? What causes lightning?
Answer:
Lightning is also an electric spark, but on a huge scale. It is caused by the accumulation of charges in the clouds.

Question 2.
What is an electric charge? What are charged objects?
Answer:
When a plastic refill is rubbed with polythene it acquires a small electric charge. Similarly when a plastic comb is rubbed with dry hair, it acquires a small charge. These objects are called charged objects.

Question 3.
What is static charge? How does it differ from electric current? ‘
Answer:
The electric charges generated by rubbing are called static charges. The static charges do not move while charges move in electric current.

Question 4.
What do you mean by electric discharge? How does it occurs?
Answer:
When the negative and positive charges meet, streaks of bright light and sound are produced. This process is called electrical discharge. For example, electric discharge occurring between two or more clouds or between clouds and earth.

Question 5.
What is earthing? What is the application of earthing?
Answer:
The process of transfer of charges from a charged object to the earth is called earthing. It is provided in buildings to protect from electrical shocks due to any leakage of electrical current.

Question 6.
How does electric discharge occur in clouds?
Answer:
At the time of thunder negative charges are accumulated near the clouds and positive charges near the ground. When these charges meet, electric discharge takes place between the ground and clouds. In this process, a large amount of energy is released.

Question 7.
What is lightning conductor? Where is it fixed?
Answer:
Lightning conductor is a device which is used to protect buildings from the danger of lightning. It is fixed at the top of the building.

Question 8.
What is an earthquake? How is it caused?
Answer:
Sudden shaking and trembling of earth is called an earthquake. It is caused mostly due to the movement of earth’s plates inside the crust.

Question 9.
What are fault zones? Name the fault zones in India.
Answer:
Since earthquakes are caused by the movement of plates, the boundaries of the plates are weak zones where earthquakes are more likely to occur. The weak zones are also known as seismic or fault zones. In India the most threatened areas or fault zones are Kashmir, Western and Central Himalayas, the Indo-Gangetic Plain, Rann of Kutch, etc.

Question 10.
How can tremors be caused?
Tremors on the earth can also be caused when a volcano erupts, or a meteor hits the earth, or an underground nuclear explosion is carried out.

Question 11.
What are seismic waves? How are these waves recorded?
Answer:
The tremors produce waves on the surface of the earth. These are called seismic waves. These waves are recorded by an instrument called the seismograph.

Some Natural Phenomena Class 8 Extra Questions Long Answer Type

Question 1.
What is lightning? How does lightning strike?
Answer:
Lightning is an electric spark, but on a huge scale. It is caused by the accumulation of charges in the clouds. When two clouds carrying opposite charges come very close to each other, the charges flow with great speed from one cloud to another through the air between them. Consequently, a very bright spark is produced.

The spark caused due to the transfer of electric charge between two clouds causes lightning. It can occur when electric charges flow from one part of a cloud to another or from a cloud to the ground. Lightning is accompanied by large amounts of electric charges and very high temperatures. The huge amount of heat produced makes the air expand very suddenly what causes vibration to occur, resulting in a loud sound called thunder.

Question 2.
Explain the process of electric discharge.
Answer:
During the development of a thunderstorm, the air currents move upward while the water droplets move downward. These vigorous movements cause separation of charges. By a process, the positive charges collect near the upper edges of the clouds and the negative charges accumulate near the lower 1 edges. There is accumulation of positive near the ground also.

When the magnitude of the accumulated charges becomes very large, the air which is normally a poor conductor of electricity, is no longer able to resist their flow. Finally negative and positive charges meet, producing streaks of bright light and sound called lightning and thunderstorm respectively. This process is known as electric discharge. This can occurs between two or more clouds, or between clouds and the earth.

Question 3.
What safety measures should be taken during lightning and thunderstorm?
Answer:
The following safety measures are advisable to be adopted to protect from lightning and thunderstorm:

• No open place is safe. A house or a building is a safe place. If travelling by car or by bus, it is safe to stay inside with windows and doors of the vehicle shut.
• If we are outside, the following things are important to be kept in mind:

(a) Open vehicles, like motorbikes, tractors, construction machinery, fields, tall trees, shelters in parks, elevated places do not protect us from lightning strikes.
(b) Carrying an umbrella is not at all a good idea during thunderstorms.
(c) If no shelter is available and we are in an open field, we should keep away from all trees. We should stay away from poles or other metal objects. We should not lie on the ground. Sitting in a pose as given in the Fig. 15.8 is advisable.

• If we are inside the house, we should take care as advised further: Lightning can strike telephone cords, electrical wires and metal pipes. During a thunderstorm, contact with these should be avoided. It is safer to use mobile phones and cordless phones. However, it is not wise to call up a person with a wired phone. Bathing should be avoided. Electrical appliances should be unplugged.

Question 4.
What is a lightning conductor? How does it work?
Answer:
Lightning conductor is a device used to protect buildings from the effect of lightning. A metallic rod, taller than the building, is installed in the walls of the buildings during its construction. One end of the rod is kept out in the air and the other is buried deep in the ground as shown in the figure. The rod provides easy route in the transfer of electric charge to the ground. The metal columns used during construction, electrical wires and water pipes in the buildings also protect us to an extent. But we should not touch them during thunderstorm.

Question 5.
What is an earthquake? What causes an earthquake? Explain.
Answer:
An earthquake is a sudden shaking or trembling of the earth. It lasts for a very short time. It is caused by a disturbance deep inside the earth’s crust. We know that tremors are caused by the disturbance deep down inside the uppermost layer of the earth called crust (Fig. 15.10). The outermost layer of the earth is fragmented. Each fragment is called a plate (Fig. 15.11). These plates are in continual motion. When they brush one another, or a plate goes under another due to collision (Fig. 15.12), they cause disturbance in the earth’s crust. It is this disturbance that shows up as an earthquake on the surface of the earth.

Question 6.
What are the measures we should adopt to protect against an earthquake?
Answer:
We know that earthquakes cannot be predicted. It is, therefore, important that we should take necessary precautions to protect ourselves all the time as given below:

• In seismic zones it is advisable to make the structure of the buildings simple so that it is ‘Quake Safe’. Modern building technology can make it possible.
• In highly seismic areas, the use of mud or timber is better than using heavy construction materials.
• Since some buildings may catch fire, it is necessary that all buildings, especially tall buildings, have fire fighting equipment in working order.
• If we are at home, we should take shelter under a table and stay there till the shaking stops. We should stay away from tall and heavy objects that may fall on us. If we are in bed, we should protect our head with a pillow.
• If we are at outdoors, we should find a clear spot, away from buildings, trees and overhead power lines and drop to the ground. If travelling in a car or a bus, do not come out and drive slowly to a clear spot.

Some Natural Phenomena Class 8 Extra Questions HOTS

Question 1.
If aluminium strips of an electroscope are replaced by plastic strips and a charged body is brought in contact with the metal clip. What will happen?
Answer:
The plastic strips will show repulsion. Charges from the charge body will be transfer from the metal rod to the plastic strips. As a result, similar charges will develop on the plastic strips and repulsion will occur.

Question 2.
If a charged plastic straw is brought near another uncharged plastic straw, what will happen?
Answer:
They will attract each other due to presence of unlike charges on them.

Question 3.
During construction of a building, the lightning conductor was a little shorter and cannot be buried in the ground. Would the lightning conductor be still effective? Explain.
Answer:
No, it will not be effective. Since lightning conductor was not connected properly to the earth, therefore, the charge will not pass through to the earth.

Question 4.
If air and cloud were good conductors of electricity, do you think lightning could occur? Explain.
Answer:
If air and cloud were good conductors of electricity then charge separation will not take place and hence lightning will not occur.

Question 5.
The strips of an electroscope diverge when a charged body is brought in contact with the metal clip.
What will happen to the strips if we gently touch the metal clip with hands?
Answer:
The strips will collapse due to discharging of the charges through our hand.

Question 6.
On a dry day why do you get a slight shock on touching the screen of a television or computer monitor (with picture tube)?
Answer:
Electric charges accumulated on the screen of television or computer monitor get discharge through our body. Thus, we get a slight shock.

Some Natural Phenomena Class 8 Extra Questions Value Based (VBQs)

Question 1.
Ms Neena, Science teacher of class VIII, taught children how to protect themselves and what to do during an earthquake. She even performed an earthquake drill in school for better understanding in children. Children enjoyed this drill and learned a lot from this.
(a) What to do during an earthquake if you are stuck indoor?
(b) What causes earthquakes?
(c) How you must keep yourself ready for an earthquake?
(d) What values of Ms Neena is shown here?
Answer:
(a) The following must be done if someone had stuck indoor:

• Stay away from glass, windows, outside doors and walls.
• Stay away from anything that could fall such as lightning fixtures or furnitures.
• Get under a sturdy table/desk, hold it firmly and cover your head.
• Stay calm and do not panic. Stay inside until shaking stops and it is safe to go outside.

(b) Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake.

(c) We must keep ourself ready for an earthquake by:

• Having proper knowledge about do’s and don’ts during an earthquake.
• Keeping a disaster kit ready in the time of need.
• Helping needy and injured person after an earthquake.

(d) Ms Neena has future vision, scientific temperament, intelligent, compassionate, caring, dedicated, etc.

MCQ Questions for Class 8 Science: Ch 14 Chemical Effects of Electric Current

1. Which of the following does not conduct electricity?

(a) Sugar solution

(b) Vinegar solution

(c) Lemon juice solution

(d) Caustic soda solution

► (a) Sugar solution

2. An electric lamp glows due to        

(a) Chemical effect        

(b) Magnetic effect        

(c) Heating effect        

(d) None

► (c) Heating effect        

3. Battery is a

(a) Large single cell

(b) Combination of two or more cells

(c) Combination of two cell only

(d) Combination of cell and conductor

► (b) Combination of two or more cells

4. Potential difference is created in a electric circuit due to
(a) Switch
(b) Cell or battery
(c) Voltmeter
(d) Conductor
► (b) Cell or battery

5. In electrolytic solutions, which of the following acts as carrier of charge?

(a) Protons

(b) Electrons

(c) Neutrons

(d) Ions

► (d) Ions

6. Fuse wire is used in electric circuit to prevent

(a) Electrical appliances and circuit from high current

(b) Prevent the insulator

(c) Us from electric shock

(d) Prevent the ammeter

► (a) Electrical appliances and circuit from high current

7. Which of the appliances at your home does not run on electric current?

(a) Television

(b) Mixer grinder

(c) Air conditioner

(d) Gas burner

► (d) Gas burner

8. The passage of an electric current through a solution causes

(a) Heating effect

(b) Lighting effect

(c) Chemical effect

(d) All of these

► (c) Chemical effect

9. In a dry cell, which of the following acts as the positive terminal?

(a) Carbon rod

(b) Manganese dioxide

(c) Manganese dioxide and powdered carbon

(d) A metal cap on the carbon rod

► (d) A metal cap on the carbon rod

10. Electroplating is based on:

(a) magnetic effect of electricity

(b) chemical effect of electricity

(c) heating effect of electricity

(d) physical effect of electricity

► (b) chemical effect of electricity

11. Distilled water is

(a) Poor conductor

(b) Good conductor

(c) Both (a) and (b)

(d) None

► (a) Poor conductor

12. A device which prevents or allow the current to flow through it

(a) Conductor

(b) Motor

(c) Terminal

(d) Switch

► (d) Switch

13. What is current?

(a) The flow of matter

(b) The flow of electrons

(c) The flow of protons

(d) The flow of charge

► (d) The flow of charge

14. Electric current is measured by a device

(a) Odometer

(b) Voltmeter

(c) Ammeter

(d) Galvanometer

► (c) Ammeter

15. In battery two or more cells are connected in

(a) Series

(b) Random

(c) Positive and positive terminals

(d) Parallel

► (a) Series

16. Which of the following liquids is a bad conductor of electricity?

(a) Lemon juice

(b) Vinegar

(c) Sea water

(d) Distilled water

► (d) Distilled water

17. Which acid is present in lemon juice that acts as an electrolyte?

(a) Sulphuric acid

(b) Nitric acid

(c) Hydrochloric acid

(d) Citric acid

► (d) Citric acid

18. Which categories of substance are generally good conductors?

(a) Insulator

(b) Non-metals

(c) Metals

(d) Reflector

► (c) Metals

19. An electric lamp glows due to

(a) Chemical effect

(b) Magnetic effect

(c) Heating effect

(d) None

► (c) Heating effect

20. Which metal is electroplated on iron for making “cans” for storing food and drinks?

(a) Chromium metal

(b) Silver metal

(c) Tin metal

(d) Copper metal

► (c) Tin metal

21. Which of the following are the characteristics of an electrolyte?

(a) It has a positive charge.

(b) It has a negative charge.

(c) It conducts charge without dissociating.

(d) It forms positive and negative ions.

► (d) It forms positive and negative ions.

22. What is the common name for manganese-dioxide-alkaline-zinc cell?

(a) Moz cell

(b) Long life cell

(c) Manganese-dioxide

(d) Alkaline cell

► (d) Alkaline cell

23. Which of the following is an insulator?

(a) Wood

(b) Iron

(c) Graphite

(d) Silver

► (a) Wood

24. In electric circuit, current flows due to

(a) Difference in temperature

(b) Same potential difference

(c) Difference in potential difference

(d) Difference in current

► (c) Difference in potential difference

25. The bulb glows when the electric current passes through it due to

(a) Lighting effect of electric current

(b) Magnetic effect of electric current

(c) Heating effect of electric current

(d) Chemical effect of electric current

► (c) Heating effect of electric current

Class 8 Science Chapter 14 Extra Questions and Answers Chemical Effects of Electric Current

Extra Questions for Class 8 Science Chapter 14 Chemical Effects of Electric Current with Answers Solutions

Chemical Effects of Electric Current Class 8 Extra Questions Very Short Answer Type

Question 1.
What are good conductors?
Answer:
The substances that conduct electricity through them are called good conductors.

Question 2.
What are insulators or poor conductors?
Answer:
The substances that do not conduct electricity through them are poor conductors or insulators.

Question 3.
Give four examples of conductors.
Answer:
Copper, iron, aluminium and brass.

Question 4.
Give four examples of insulators.
Answer:
Air, wood, rubber and plastic.

Question 5.
Name two metal objects which have a coating of another metal.
Answer:
Handlebars of bicycles, bathroom taps.

Question 6.
What do we get on electrolysis of acidified water?
Answer:
Hydrogen and oxygen gas.

Question 7.
Is air a bad or good conductor?
Answer:
A bad conductor.

Question 8.
Which metal is plated on handle bars of cycles and rim of wheels?
Answer:
Chromium

Question 9.
What is the full form of LED?
Answer:
Light Emitting Diode.

Question 10.
How do we check the electric current?
Answer:
We check the electric current by using a tester.

Question 11.
Which part of an atom is responsible for flow of current?
Answer:
Electron

Question 12.
Why do most liquids conduct electricity?
Answer:
Due to the presence of ions in them, most liquids conduct electricity.

Question 13.
An LED is more efficient device than a bulb. Why?
Answer:
LED is more efficient because it can glow even when a weak or less current flows through it.

Question 14.
Do lemon juice or vinegar conduct electricity?
Answer:
Yes, they conduct electricity.

Question 15.
How is conductivity of liquids tested?
Answer:
By using a tester.

Question 16.
Is water from taps, handpumps, wells and ponds a good conductor?
Answer:
Yes, water from these sources is a good conductor.

Question 17.
What makes distilled water a good conductor?
Answer:
Salts when mixed with distilled water make it a good conductor.

Question 18.
Why is a layer of zinc coated over iron?
Answer:
To prevent iron from corrosion and rust.

Question 19.
Will the solution of sugar in distilled water conduct electricity?
Answer:
No

Question 20.
Why is tin electroplated on iron to make cans used for storing food?
Answer:
Tin is less reactive than iron. Tin coating prevents food from coming in contact with iron and thus pre¬vents it from getting spoiled or corroded.

Question 21.
Why we ifse chromium electroplating on taps and bars of bicycle instead of silver and gold?
Answer:
Silver and gold are very expensive comparatively to chromium.

Question 22.
What type of effect of current do the deposits of metal on electrodes show?
Answer:
Chemical effect

Question 23.
What effect of current does electroplating show?
Answer:
Chemical effect

Question 24.
Which effect of current causes the bulb to glow?
Answer:
Heating effect

Question 25.
Which part of the bulb glows?
Answer:
Filament

Question 26.
Name the three effects of electric current.
Answer:
Heating, magnetic and chemical effect.

Question 27.
How can the magnetic effect of current be checked?
Answer:
By using magnetic compass.

Question 28.
What do we see when the compass needle is brought near a wire in which current is flowing?
Answer:
The needle deflects.

Question 29.
What is electroplating?
Answer:
Deposition of thin layer of a metal over other metal by electrolysis is called electroplating.

MCQ Questions for Class 8 Science: Ch 13 Sound

1. Sound is a kind of

(a) work

(b) energy

(c) force

(d) pressure

► (b) energy

2. 1 hertz is equal to

(a) 1 vibration per minute

(b) 10 vibrations per minute

(c) 600 vibrations per minute

(d) 60 vibrations per minute

► (d) 60 vibrations per minute

3. In which medium sound travels faster?

(a) Metals

(b) Water

(c) Same in all medium

(d) Air

► (a) Metals

4. Pitch of sound depends upon

(a) Frequency

(b) Wavelength

(c) Time-period

(d) Amplitude

► (a) Frequency

5. When we say that sound travels in a medium, what do we mean?

(a) The particles of the medium travel.

(b) The source travels.

(c) The disturbance travels.

(d) The medium travels.

► (c) The disturbance travels.

6. Eardrum is a part of:

(a) Sound producing organ

(b) Skeletal system

(c) Hearing organ

(d) Reproductive organ

► (c) Hearing organ

7. One of the most common well-known periodic motion is that of

(a) Quartz clock

(b) Sundial

(c) Simple pendulum

(d) Digital clock

► (c) Simple pendulum

8.Sound propagates maximum in

(a) gas

(b) liquid

(c) solid

(d) all

► (c) solid

9. What is the length of vocal cords in men?

(a) 15mm

(b) 20mm

(c) 5mm

(d) 10mm

► (b) 20mm

10. The voice box is also called:

(a) Stomach

(b) Heart

(c) Larynx

(d) Mouth

► (c) Larynx

11. Noise pollution is harmful for

(a) human

(b) cat

(c) bird

(d) all

► (d) all

12. Large amplitude of sound vibrations will produce:

(a) Loud sound

(b) Meak sound

(c) Slow sound

(d) Shreak

► (a) Loud sound

13. The minimum distance from sound reflecting surface to hear an echo is about

(a) 17.2 m

(b) 35 m

(c) 27.2 m

(d) 20 m

► (a) 17.2 m

14. Sound lost more energy in

(a) air

(b) vacuum

(c) liquid

(d) solid

► (a) air

15. An object oscillates 50 times in one second. What is its frequency?

(a) 0.2 Hz

(b) 0.02 Hz

(c) 0.002 Hz

(d) 50 Hz

► (d) 50 Hz

16. Sound of single frequency is called a

(a) Noise

(b) Tone

(c) Note

(d) Music

► (b) Tone

17. Ultrasound is used in

(a) X-rays

(b) Echocardiography

(c) Speedometer

(d) Micrometer

► (b) Echocardiography

18. In human beings, which of the following produces the sound?

(a) Larynx

(b) Wind pipe

(c) Eardrum

(d) Lungs

► (a) Larynx

19. When a tightly stretched band is plucked it

(a) Only oscillate to and fro

(b) Produce sound but do not vibrate

(c) Vibrate but do not produce sound

(d) Vibrate and produce sound

► (d) Vibrate and produce sound

20. On what factors does the pitch of sound depend?

(a) Frequency

(b) Amplitude

(c) Loudness

(d) The distance from source

► (a) Frequency

21. The SI unit of frequency is

(a) Lambda

(b) Hertz

(c) Meter

(d) Decibel

► (b) Hertz

22. Ultrasound equipment for investigating and tracking medical problems, works at frequency

(a) At any frequency

(b) At 20000 Hz only

(c) Higher than 20000 Hz

(d) Lower than 20000 Hz

► (c) Higher than 20000 Hz

23. In most of the cases vibration of objects are not visible because

(a) Wavelength is very large

(b) Wavelength is very small

(c) Amplitude is very small

(d) Frequency is very less

► (c) Amplitude is very small

24. What is the number of vibrations made by a body in one second called?

(a) Frequency

(b) Wavelength

(c) Loudness

(d) Pitch

► (a) Frequency

25. Loudness of sound depends upon its

(a) Wavelength

(b) Amplitude

(c) Frequency

(d) Time-period

Class 8 Science Chapter 13 Extra Questions and Answers Sound

Extra Questions for Class 8 Science Chapter 13 Sound with Answers Solutions

Sound Class 8 Extra Questions Very Short Answer Type

Question 1.
What does voice box or larynx of human produces?
Answer:
Sound

Question 2.
In which medium sound propagates the maximum?
Answer:
Solid

Question 3.
Name the sound producing organ in human.
Answer:
Larynx

Question 4.
What is vibration?
Answer:
Back and forth motion of an object.

Question 5.
Do all bodies produce sound?
Answer:
No

Question 6.
How is sound produced?
Answer:
By vibrating bodies.

Question 7.
Name a musical instrument which produces sound by blowing air into it.
Answer:
Flute

Question 8.
What is the unit of frequency?
Answer:
Hertz

Question 9.
What do you mean amplitude?
Answer:
Vibrations produced by vibrating body in one second is known as amplitude.

Question 10.
What is the maximum displacement of an oscillating object is called?
Answer:
Amplitude

Question 11.
How does sound help us?
Answer:
Sound help us to communicate.

Question 12.
What is the unit of loudness?
Answer:
Decibel (dB)

Question 13.
What is audible sound?
Answer:
Frequency between 20 Hz to 20,000 Hz is an audible sound.

Question 14.
In which medium sound travels faster?
Answer:
Solid

Sound Class 8 Extra Questions Short Answer Type

Question 1.
A simple pendulum makes 20 oscillations in 40 seconds. What is the time period and frequency of its oscillation?
Answer:

Question 2.
Sonali heard sound of thunderbolt 5 second after she saw flash of lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s)
Answer:
Distance of Sonali from the place of lightning = 330 x 5 = 1650 m

Question 3.
What is frequency?
Answer:
The number of oscillations per second is called frequency. Its unit is hertz.

Question 4.
What do you mean by oscillatory motion?
Answer:
The to and fro motion of an object is called vibration. This motion in both the direction from its mean position is called oscillatory motion.

Question 5.
Two astronauts are floating close to each other in space. Can they talk to each other without using any special device? Give reasons.
Answer:
No, because in space there is no atmosphere and sound needs medium to travel.

Question 6.
What do you mean by time period?
Answer:
The time taken by a vibrating body to complete one oscillation is called the time period.

Question 7.
What are the harms of noise pollution?
Answer:
Lack of sleep, hypertension, anxiety and temporary or even permanent impairment of hearing.

Question 8.
What do you mean by audible sound?
Answer:
The sound which we can hear clearly is known as audible sound. It has a range of frequencies from 20 Hz to 20,000

Question 9.
What are infrasonic sounds?
Answer:
Answer:
Sounds which have frequency lower than 20 Hz are called infrasonic sounds.

Question 10.
What is noise pollution?
Answer:
The presence of unwanted and excessive sound in the environment is called noise pollution.

MCQ Questions for Class 8 Science: Ch 12 Friction

1. Which of the following produces least friction?

(a) Sliding friction

(b) Rolling friction

(c) Composite friction

(d) Static friction

► (b) Rolling friction

2. In machine, friction between moving parts is reduced by

(a) Heating machine

(b) Using powder

(c) Using lubricants

(d) Using paints

► (c) Using lubricants

3. Why is a carrom board usually powdered before playing?

(a) For increasing friction

(b) For decreasing friction

(c) For decoration

(d) For fragrance

► (b) For decreasing friction

4. Thermos flask keeps hot liquid hot and cold liquid cold by

(a) Heating

(b) Friction

(c) Preventing heat loss

(d) Cooling

► (c) Preventing heat loss

5. Substances are called lubricants which are used to

(a) increase friction

(b) decrease friction

(c) increase or decrease friction

(d) none of these

► (b) decrease friction

6. Which force prevents us from slipping while walking on the road?

(a) Muscular force of our body

(b) Gravitational pull by the earth

(c) Frictional force

(d) Balanced forces of nature

► (c) Frictional force

7. Which of the following activities is easier to perform on a drum of 10 kg?

(a) Dragging the drum

(b) Lifting the drum

(c) Rolling the drum

(d) All of the above need the same effort

► (c) Rolling the drum

8. The substance which reduce friction are called

(a) Lubricants

(b) Wheels

(c) Powder

(d) Graphite

► (a) Lubricants

9. A toy car released with the same initial speed will travel farthest on

(a) Muddy surface

(b) Cemented surface

(c) Brick surface

(d) Polished marble surface

► (d) Polished marble surface

10. Which of the following materials is likely to have the least friction?

(a) Wood

(b) Cardboard

(c) Glass

(d) Paper

► (c) Glass

11. Friction is a __________

(a) Contact force       

(b) Non-contact force       

(c) Magnetic force       

(d) None of these

► (a) Contact force       

12. Fluids are

(a) gases

(b) liquids

(c) gases and liquids both

(d) none of these

► (c) gases and liquids both

13. In the decreasing order of magnitude, which of the following is correct?

(a) Rolling < static < sliding friction

(b) Static > sliding > rolling friction

(c) Static > rolling > sliding friction

(d) Sliding < static < rolling friction

► (b) Static > sliding > rolling friction

14. Which of the following statements is NOT true?

(a) Friction can be reduced by converting sliding friction into rolling friction.

(b) Friction in air and water can be reduced by streamlining the shape of the objects.

(c) A polished surface will have less friction.

(d) Friction can be reduced to zero.

► (d) Friction can be reduced to zero.

15. Striking a matchstick produces fire by

(a) Contact force

(b) Friction

(c) Chemical reaction

(d) Physical reaction

► (b) Friction

16. The shape of fish is streamlined to

(a) Change the direction

(b) Increase fluid friction

(c) Facilitate breathing

(d) Decrease fluid friction

► (d) Decrease fluid friction

17. Friction produces

(a) Motion

(b) Force

(c) Heat

(d) Light

► (c) Heat

18. Why are certain bodies streamlined?

(a) To increase friction

(b) To decrease weight

(c) To reduce friction

(d) To increase weight

► (c) To reduce friction

19. Carpenters often grease screws before fixing them to

(a) Decrease friction

(b) Increase friction

(c) Make it light weight

(d) All of the above

► (a) Decrease friction

20. Soapy water on floor would make it

(a) More clean

(b) Difficult to walk

(c) More hygienic

(d) Easier to walk

► (b) Difficult to walk

21. Brakes of vehicle is stopped by using brake that works on property of

(a) Pressure

(b) Acceleration

(c) Retardation

(d) Friction

► (d) Friction

22. Friction always

(a) helps the motion

(b) opposes the motion

(c) both of these

(d) none of these

► (b) opposes the motion

23. If a body moves on the sandy surface, its motion will

(a) Increase

(b) Decrease

(c) Neither increase nor decrease

(d) None of these

► (b) Decrease

24. Why are spikes provided in the shoes of athletes?

(a) As a decoration

(b) To increase friction

(c) To decrease friction

(d) To give shape

► (b) To increase friction

25. Which of the following will offer least friction to run a toy car?

(a) Wet marble

(b) Towel

(c) Dry marble

(d) News paper

► (a) Wet marble

Class 8 Science Chapter 12 Extra Questions and Answers Friction

Extra Questions for Class 8 Science Chapter 12 Friction with Answers Solutions

Friction Class 8 Extra Questions Very Short Answer Type

Question 1.
What is the force of friction?
Answer:
The force acting on a moving object equal and opposite to the direction of motion is called force of friction.

Question 2.
What is the cause of friction?
Answer:
The irregularities on the two surfaces in contact is the cause of friction.

Question 3.
What is the force responsible for wearing out of bicycles tyres?
Answer:
Frictional force

Question 4.
Is the friction same for all objects?
Answer:
No

Question 5.
Why are wheels of vehicles made circular?
Answer:
Rolling friction is less than sliding friction.

Question 6.
What is the direction of force of friction acting on a moving object?
Answer:
Opposite to the direction of moving objects.

Question 7.
Why do pieces of luggage fit with rollers?
Answer:
To reduce friction and to pull them easily.

Question 8.
Why does a matchstick catch fire when rubbed on the rough surface of the box?
Answer:
Due to friction between the stick and rough surface a matchstick catches fire.

Question 9.
What is the name of special shape given to objects moving in fluids?
Answer:
Streamlined

Question 10.
Give one example where ball bearings are used.
Answer:
Ceiling fan

Question 11.
Does friction depend on the nature of objects?
Answer:
Yes

Question 12.
What is the use of lubricants?
Answer:
They are used to reduce friction.

Question 13.
Which surface does produce more friction smooth or rough surface?
Answer:
Rough surface

Question 14.
Why is fine powder sprinkled on the carrom board?
Answer:
In order to reduce friction powder is sprinkled on carrom board.

Question 15.
Why is it difficult to walk on the wet marble floor?
Answer:
The wet marble floor has less friction. So it is difficult to move on it.

Question 16.
Why does the jar of a mixer become hot when it is run for few minutes?
Answer:
It becomes hot due to friction.

Question 17.
Name the types of friction.
Answer:

• Static friction
• Sliding friction
• Rolling friction
• Fluid friction

Question 18.
Which force helps us to write on the paper or blackboard?
Answer:
Frictional force

Question 19.
What is drag?
Answer:
The frictional force exerted by fluids is called drag.

Question 20.
What are fluids?
Answer:
Commonly gases and liquids are called fluids.

Question 21.
Give some examples having streamlined body.
Answer:
Aeroplanes, birds, ships, etc.

Question 22.
Oil, creams and grease are called lubricants. Why?
Answer:
Because they reduce friction.

Question 23.
How can fluid friction be minimised?
Answer:
By giving suitable shapes to bodies moving in fluids.

Question 24.
When does static friction come into play?
Answer:
When we try to move an object at rest, static friction comes into play.

Question 25.
Can we reduce friction to zero?
Answer:
No

Friction Class 8 Extra Questions Short Answer Type

Question 1.
If we push the book on the table, it stops after sometime. Why?
Answer:
When we push the book on a table, a force is applied on it in the opposite direction of the motion called force of friction. This force opposes the movement and the book stops.

Question 2.
Why are the worn-out tyres discarded?
Answer:
The worn out tyres are discarded because their tread are worn off and limiting their effectiveness of providing required amount of friction.

Question 3.
Why is it easier for the fish to swim in water?
Answer:
Fish can easily swim in water because it has a streamlined body which produces less friction. So it easily cuts through water and moves in it very easily.

Question 4.
Give some examples to show that friction produces heat.
Answer:
The examples are:

• Rubbing of our hands to keep us warm in winter.
• Rubbing of matchsticks on the rough surface to make fire.

Question 5.
Give some examples of smooth and rough surfaces.
Answer:
Smooth surfaces: Surface of the mirror, surface of wet soaps, glazed tiles, surface of an oily pot, etc.
Rough surfaces: Surface of plyboard, unpainted wall, brick, tyres, etc.

Question 6.
What is a spring balance?
Answer:
A spring balance is a device which measures the force acting on an object. It contains a coiled spring. When a force is applied on it, the spring gets stretched. The pointer moves on the scale showing the magnitude of the force.

Question 7.
How does the friction depend on the nature of the surface?
Answer:
Nature of the surface is one of the factors affecting friction. When we move on any surface, we apply a force to overcome the interlocking of the surfaces. Rough surfaces have a larger number of irregularities and greater frictional force.

Question 8.
What are the two factors on which the force of friction depends?
Answer:
These two factors are:

• The nature, i.e., smoothness or roughness of the surfaces in contact.
• How the surfaces in contact pressed together.

Question 9.
When the two surfaces are pressed harder, friction increases. Explain why?
Answer:
The friction is caused by the interlocking of irregularities in the two surfaces. It is obvious that the force of friction will increase if two surfaces are pressed harder. This can be experienced by dragging a mat when nobody is sitting on it and when a person is sitting on it.

Question 10.
What is a measure of static friction?
Answer:
The force required to overcome friction at an instant an object starts moving from rest is a measure of static friction.

Question 11.
What is a measure of sliding friction?
Answer:
The force required to keep the object moving with the same speed is a measure of sliding friction.

Question 12.
Why is it easier to move the box already in motion than to get it started?
or
The sliding friction is slightly smaller than the static friction. Explain why?
Answer:
When the box starts sliding, the contact points on its surface, do not get enough time to lock into the contact points on the floor. So, the sliding friction is slightly smaller than the static friction. Hence, it is somewhat easier to move the box already in motion than to get it started.

Question 13.
Why are the soles of shoes and tyres of vehicles grooved?
Answer:
The soles of shoes and tyres of vehicles like cars, trucks, etc., are grooved to provide better grip on the floor or roads to move safely because grooving increases friction.

Question 14.
We use ball bearings between the hub and axle of ceiling fan and bicycles. Why?
Answer:
The rolling friction is smaller than the sliding friction. In most machines, sliding is replaced by rolling by using ball bearings to reduce friction. This is why ball bearings are used between the hub and axle of ceiling fan and bicycle.

Question 15.
Why are lubricants applied between the moving part of a machine?
Answer:
When lubricants are applied between the moving part of a machine, a thin layer is formed there and moving surfaces do not directly rub against each other. Interlocking of irregularities is avoided to a great extent and the movement becomes smooth.

Question 16.
How brake stop moving bicycles and automobiles?
Answer:
When we press the brake lever, the brake pads arrest the motion of the rim due to friction and the wheel stops moving. This is how brake stops moving bicycles and automobiles.

Question 17.
People often rub their hands in winter. Why?
Answer:
Friction produces heat. When we rub our hands together, the friction arises between them and heat is produced. This makes our hands warm. This is why people often rub their hands in winter.

Question 18.
Which factors affect fluid friction?
Answer:
The speed of the object with respect to the fluid, shape of the object and nature of the fluid affect fluid friction.

Question 19.
In some cases, we deliberately increase friction. Explain why?
Answer:
We need to increase friction in some cases like grooving in the sole of shoes, the treaded tyres of cars, trucks or other vehicles, using brake pads in the brake system of bicycles and automobiles. If we do not do so, we may slip on the floor or roads, vehicles may slip on the roads and they will not stop, our bicycles and automobiles will not stop, etc.

HomeClass8science-mcq

MCQ Questions for Class 8 Science: Ch 11 Force and Pressure

 02 Sept, 2020

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MCQ Questions for Class 8 Science: Ch 11 Force and Pressure

1. Force acting on per unit area is called

(a) non-contact forces

(b) contact forces

(c) force

(d) pressure

► (d) pressure

2. The strength of a force is usually expressed by its

(a) Altitude

(b) Duration

(c) Direction

(d) Magnitude

► (d) Magnitude

3. When two forces act in opposite directions, then net force acting is the

(a) Sum of two forces

(b) Difference between two forces

(c) Both of these

(d) None of these

► (b) Difference between two forces

4. Which of the following actions describe pushing force?

(a) Kicking

(b) Lifting

(c) Picking

(d) Opening

► (a) Kicking

5. Magnetic force is

(a) Contact force

(b) Non-contact force

(c) both (a) and (b)

(d) None

► (b) Non-contact force

6. Force is a

(a) Pull

(b) Push

(c) Pull and push both

(d) None of these

► (c) Pull and push both

7. Which one is an example that shows that force can change shape and size of object?

(a) Force applied to increase the speed

(b) Force applied on cricket ball

(c) Force applied on large stone

(d) Force applied on inflated balloon

► (d) Force applied on inflated balloon

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

(a) Magnetic force

(b) Gravitational force

(c) Electrostatic force

(d) Muscular force

► (c) Electrostatic force

9. Which of the following examples describe the change of shape on applying force?

(a) A ball being kicked

(b) A fan switched on

(c) A man jumping from a height

(d) Repeatedly tearing of a paper

► (d) Repeatedly tearing of a paper

10. A force applied on an object may change its

(a) Colour

(b) Mass

(c) Weight

(d) Speed

► (d) Speed

11. Four forces are acting on a body. If the body does not change its position or shape/then what does it mean?

(a) Forces are similar acting in the same direction.

(b) Forces are parallel and opposite.

(c) Forces add up to zero when taken as vectors.

(d) Forces are different acting in the same direction.

► (c) Forces add up to zero when taken as vectors.

12. A push or pull on an object is called

(a) Gravitation

(b) Pressure

(c) Push-pull

(d) Force

► (d) Force

13. How does the pressure exerted by a liquid change?

(a) Increases with depth

(b) Decreases with depth

(c) Remains constant

(d) First increases and then decreases

► (a) Increases with depth

14. A force is applied on an object in the direction of its motion. What is the effect of force on the object?

(a) The speed of the object will increase.

(b) The speed of the object will decrease.

(c) The speed of the object will remain unchanged.

(d) The object comes to rest.

► (a) The speed of the object will increase.

15. Leaves or fruits fall on the ground due to

(a) Magnetic force

(b) Gravitational force

(c) Electrostatic force

(d) Muscular force

► (b) Gravitational force

16. Which of the following effects is caused by frictional force?

(a) Change in the shape of an object

(b) Change in the direction of the motion of an object

(c) Slowing down of a moving object

(d) Acceleration in a moving body

► (c) Slowing down of a moving object

17. State of motion is described by

(a) Position of rest

(b) Position of motion

(c) Both by the state of rest or motion

(d) None of these

► (c) Both by the state of rest or motion

18. Force of gravity is a

(a) Repulsive force

(b) Attractive force

(c) Contact force

(d) Neither attractive nor repulsive force

► (b) Attractive force

19. Force applied on an object in same direction

(a) Divide on another

(b) Add to one another

(c) Multiply on another

(d) Subtract to one another

► (b) Add to one another

20. What causes the atmospheric pressure?

(a) The sky above our head

(b) The air surrounding the earth

(c) The gravitational force of the sun and other planets

(d) The mass of the earth

► (b) The air surrounding the earth

21. A When does a body float on water?

(a) When no force is acting on it.

(b) When the net force acting on the body is zero

(c) When there is a gravitational pull.

(d) When there is friction between the body and the water

► (b) When the net force acting on the body is zero

22. If no force acts on a body at rest, then what effect can be observed?

(a) The body changes shape.

(b) The body moves with increased speed.

(c) The body remains at rest.

(d) The body breaks up.

► (c) The body remains at rest.

23. Which of the following is a non-contact force?

(a) Muscular force

(b) Electrostatic force

(c) Elastic spring force

(d) Frictional force

► (b) Electrostatic force

24. Gravitational force is acting on

(a) Only on moon

(b) Only on other planets

(c) Only on earth

(d) All bodies

► (d) All bodies

25. The tendency of a body to maintain its state of rest or uniform motion is called

(a) Gravity

(b) Inertia

(c) Weight

(d) Acceleration

► (b) Inertia

Class 8 Science Chapter 11 Extra Questions and Answers Force and Pressure

Extra Questions for Class 8 Science Chapter 11 Force and Pressure with Answers Solutions

Force and Pressure Class 8 Extra Questions Very Short Answer Type

Question 1.
What is the name of the instrument used to measure atmospheric pressure?
Answer:
Barometer

Question 2.
Give two examples of contact force.
Answer:

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• Muscular force
• Force of friction

Question 3.
Name the force exerted on a ball of dough to make a flat chapati.
Answer:
Muscular force

Question 4.
What kind of force is an electrostatic force?
Answer:
Non-contact force

Question 5.
Is the gravity a property of earth only?
Answer:
No

Question 6.
Name the force due to which every object falls on earth.
Answer:
Gravitational force

Question 7.
What do you mean by pressure?
Answer:
Force per unit area (Force/Area)

Question 8.
Do liquids and gases also exert pressure?
Answer:
Yes

Question 9.
What are the two states of motion?
Answer:

• The state of rest.
• The state of motion.

Question 10.
What kind of force is friction?
Answer:
Contact force

Question 11.
What type of force is gravitational force?
Answer:
Non-contact force

Question 12.
Is it true that force acting on an object can also change its shape?
Answer:
Yes, it is true.

Question 13.
While sieving grains, small pieces fall down. Which force pulls them down?
Answer:
Gravitational force

Question 14.
How can we change the speed and the direction of a moving body?
Answer:
By applying force.

Question 15.
What is the distance moved by an object in unit time called?
Answer:
Speed

Question 16.
Does force of gravity act on dust particles?
Answer:
Yes

Question 17.
Does the force of gravitation exist between two astronauts in space?
Answer:
Yes

Question 18.
What is a force?
Answer:
A push or pull on an object is called force.

Question 19.
What is the SI unit of pressure?
Answer:
Pascal (Pa)

Question 20.
At least how many objects are needed to apply a force?
Answer:
At least two objects are needed to apply a force.

Question 21.
Give one example of gravitational force.
Answer:
An apple falling from the tree to ground.

Question 22.
What is meant by atmospheric pressure?
Answer:
The weight of air acting per unit area is known as atmospheric pressure.

Question 23.
What do you mean by magnitude?
Answer:
The strength of a force is usually expressed by its magnitude.

Question 24.
What is muscular force?
Answer:
The force resulting due to the action of muscles is known as muscular force.

Question 25.
What is contact force?
Answer:
Force that can be applied only when it is in contact with an object is called contact force.

Question 26.
What do you mean by the term atmosphere?
Answer:
The envelope of air all around us is known as atmosphere.

MCQ Questions for Class 8 Science: Ch 10 Reaching the Age of Adolescence

1. The chemical substances which are secreted from endocrine glands are called

(a) puberty

(b) hormones

(c) estrogen

(d) adolescence

► (b) hormones

2. How many pairs of Chromosomes are found in nuclei of their cells?

(a) 22 pairs

(b) 23 pairs

(c) 24 pairs

(d) 25 pairs

► (b) 23 pairs

3. Which of the following will occur in females at puberty?

(a) Ovulation

(b) Enlargement of breasts

(c) Broadening of hips

(d) All of these

► (d) All of these

4. Puberty ends when an adolescent reaches

(a) Reproductive maturity

(b) Physical maturity

(c) Birth maturity

(d) Growth maturity

► (a) Reproductive maturity

5. The menstrual cycle stops in a women at about 50 years old. The woman is said to have reached

(a) puberty.

(b) menopause.

(c) menarche.

(d) adolescence.

► (b) menopause.

6. Which of the following does not take place during the final stage of the menstrual cycle?

(a) Further thickening of the uterine lining.

(b) Repair and growth of the uterine lining.

(c) Ovulation.

(d) Both (B) and (C)

► (c) Ovulation.

7. Which one is another terms for teenage is

(a) Maturity

(b) Puberty

(c) Adolescence

(d) Thyroid

► (c) Adolescence

8. Larynx is called

(a) Voice Box

(b) Music Box

(c) Respiratory organ

(d) None of these

► (a) Voice Box

9. Glands without ducts

(a) Mammary gland

(b) Exocrine gland

(c) Endocrine glands

(d) Pancreatic gland

► (c) Endocrine glands

10. Sebaceous gland is also known as

(a) Pancreatic gland

(b) Oil gland

(c) Sweat gland

(d) Mater gland

► (b) Oil gland

11. Thyroxine is produced by

(a) Pituitary gland

(b) Adrenal gland

(c) Thyroid gland

(d) Testes

► (c) Thyroid gland

12. In girls, secondary sexual characteristics develop between

(a) 9 and 11 years.

(b) 11 and 14 years.

(c) 15 and 18 years.

(d) 19 and 21 years.

► (b) 11 and 14 years.

13. Adolescence begins around the age of

(a) 18 years

(b) 13 years

(c) 25 years

(d) 11 years

► (d) 11 years

14. The most clearly visible change during puberty is the

(a) Sudden change of hip size

(b) Sudden formation of breast

(c) Slow growth of head

(d) Sudden increase in height

► (d) Sudden increase in height

15. Initially girls grow _____ than boys.

(a) Faster

(b) Slower

(c) Both of these

(d) None of these

► (a) Faster

16. In general, boys have a Low pitch voice while the girls have

(a) Low pitch voice

(b) Hoarse voice

(c) Deep voice

(d) High pitch voice

► (d) High pitch voice

17. Progesterone level falls during

(a) Menopause

(b) Lactation

(c) Gestation

(d) Menstruation

► (a) Menopause

18. Which among the boys and girls puberty starts earlier?

(a) Any one

(b) Boys

(c) Girls

(d) Both together

► (c) Girls

19. Incomplete development of male secondary sexual characteristics is caused due to deficiency in?

(a) Estrogen.

(b) Progesterone.

(c) Adrenaline.

(d) Testosterone.

► (d) Testosterone.

20. Which of the following is NOT a secondary sexual characteristic feature of girls?

(a) The enlargement of breasts.

(b) The deepening of voice.

(c) The menstruation begins.

(d) The growth of hair at armpit.

► (b) The deepening of voice.

21. Deficiency of which hormone cause diabetes?

(a) Insulin

(b) Estrogen

(c) Testosterone

(d) Thyroxin

► (a) Insulin

22. Puberty age in females is

(a) 10 to 12 years

(b) 12 to 14 years

(c) 8 to 10 years

(d) More than 14 years.

► (a) 10 to 12 years

23. Menstrual cycle is controlled by

(a) Time duration

(b) Physical activity

(c) Food habit

(d) Hormones

► (d) Hormones

24. The right meals for adolescents consist of

(a) Chips, noodles, coke

(b) Rice, noodles and burger

(c) Chapatti, dal, vegetable

(d) Vegetable cutlets, chips and lemon drink

► (c) Chapatti, dal, vegetable

25. Which chromosomes determine the sex of an individual?

(a) Autosomes

(b) Allosomes

(c) Plasmid

(d) Giant chromosomes

► (b) Allosomes

26. Which of the following statements is true?

(a) Boys reach puberty at an earlier age than girls.

(b) Girls reach puberty earlier than boys.

(c) At the end of rapid growth, girls are normally heavier than boys.

(d) Between the age of 4 to 12, girls grow faster than boys.

► (b) Girls reach puberty earlier than boys.

Class 8 Science Chapter 10 Extra Questions and Answers Reaching the Age of Adolescence

Extra Questions for Class 8 Science Chapter 10 Reaching the Age of Adolescence with Answers Solutions

Reaching the Age of Adolescence Class 8 Extra Questions Very Short Answer Type

Question 1.
What is Adam’s apple?
Answer:
The protruding part of the throat in males is called Adam’s apple.

Question 2.
Name the hormone in female that is produced by ovaries and helps in development of mammary glands.
Answer:
Estrogen

Question 3.
Whose height grow faster initially boys or girls?
Answer:
Girls

Question 4.
Name a gland which transports secretions through ducts.
Answer:
Sweat glands/salivary glands/ oil gland (any one).

Question 5.
What is puberty?
Answer:
The age at which boys and girls become capable of reproduction.

Question 6.
What are hormones?
Answer:
The chemical substances produced by endocrine glands are called hormones.

Question 7.
How long is a woman’s reproductive life lasts?
Answer:
Menarche to menopause.

Question 8.
Name the female hormone.
Answer:
Estrogen

Question 9.
Which gland is called master gland?
Answer:
Pituitary gland

Question 10.
What is a balanced diet?
Answer:
The meal that includes all nutrients is called a balanced diet.

Question 11.
What is menstruation?
Answer:
Extrusion of uterus lining and blood along with the unfertilised egg from the vagina is called menstruation.

Question 12.
What is menarche?
Answer:
The first menstrual flow begins at puberty and is termed as menarche.

Question 13.
What is menopause?
Answer:
Stoppage of menstruation is called menopause.

Question 14.
What causes goitre?
Answer:
Deficiency of thyroxine hormone.

Question 15.
Which gland secretes thyroxine?
Answer:
Thyroid gland

Question 16.
What are chromosomes?
Answer:
The thread-like structures in the nucleus are called chromosomes.

Question 17.
How many chromosomes are present in human cell?
Answer:
23 pairs or 46 chromosomes.

Question 18.
How many sex chromosomes are there in human cell?
Answer:
Two, i.e., one pair.

Question 19.
Which hormone is necessary for normal growth of a person?
Answer:
Growth hormone.

Question 20.
Which gland secretes insulin?
Answer:
Pancreas

Question 21.
What causes diabetes?
Answer:
Deficiency of insulin.

Question 22.
Name the chromosome present in a female.
Answer:
X chromosome

Question 23.
Name the chromosome present in a male.
Answer:
X and Y chromosomes

Question 24.
Which chromosome does the unfertilised egg contain?
Answer:
X chromosome

Question 25.
Which hormone balances the proportion of salts in the blood?
Answer:
Adrenaline

Question 26.
What decides the sex of an unborn child?
Answer:
Sex chromosome of father.

Question 27.
Name the glands other than the pituitary gland.
Answer:
Thyroid, pancreas and adrenals.

Question 28.
When does the puberty ends?
Answer:
Puberty ends when an adolescent reaches reproductive maturity.

Question 29.
Do the boys and girls undergo same physical changes at puberty?
Answer:
No

Question 30.
Why do we need to have a balanced diet?
Answer:
To keep the body healthy.

MCQ Questions for Class 8 Science: Ch 9 Reproduction in Animals

1. Internal fertilization does not occur in

(a) human

(b) dog

(c) fish

(d) cow

► (c) fish

2. Every month ______________mature egg(s) are released from ovary.

(a) Four

(b) Three

(c) Two

(d) One

► (d) One

3. The animals that produce young ones are called

(a) Oviparous

(b) Viviparous

(c) Both

(d) None of these

► (b) Viviparous

4. Which of the following statements about the human female egg cell is incorrect?

(a) It is produced when a female reaches puberty.

(b) The two ovaries in a female alternately produce the egg cells.

(c) One egg cell is usually produced by a female every 28 days.

(d) An egg cell can live in the body of a female for about a month.

► (d) An egg cell can live in the body of a female for about a month.

5. Development of baby takes place inside

(a) Oviduct

(b) Cervix

(c) Uterus

(d) Vagina

► (c) Uterus

6. The cell formed after fertilisation is called

(a) Foetus

(b) Zygote

(c) An embryo

(d) None of these

► (b) Zygote

7. Female reproductive system contains ______ of ovaries.

(a) Single

(b) Four pair

(c) A pair

(d) Two pair

► (c) A pair

8. The first cloned sheep was named

(a) Molly

(b) Dolly

(c) Gamer

(d) Toto

► (b) Dolly

9. Which part within the uterus prevents the mixing of the blood of the foetus with that of the mother?

(a) Umbilical cord  

(b) Uterus wall                   

(c) Placenta                      

(d) Water sac

► (c) Placenta                      

10. Process of formation of spermatozoa is called

(a) Oogenesis

(b) Blast genesis

(c) Spermatogenesis

(d) Semen formation

► (c) Spermatogenesis

11. The testes produce male gametes called

(a) Metaphysic

(b) Sperms

(c) Ovum

(d) Zygote

► (b) Sperms

12. In asexual reproduction

(a) No parents are involved

(b) Four parents are involved

(c) One parent is involved

(d) Two parents are involved

► (c) One parent is involved

13. Which of the following is/are paired structure in human reproductive system?

(a) Ovary                         

(b) Testes              

(c) Fallopian tube  

(d) All of these

► (d) All of these

14. Type of reproduction in which fusion of male and female gametes takes place is called

(a) Cellular reproduction

(b) Asexual reproduction

(c) Vegetative reproduction

(d) Sexual reproduction

► (d) Sexual reproduction

15. Which of the following sequences is in the correct order?

(a) Zygote → Embryo → Foetus → Baby

(b) Zygote → Embryo → Baby → Foetus

(c) Embryo→ Zygote → Baby → Foetus

(d) Foetus → Zygote → Embryo → Baby

► (a) Zygote → Embryo → Foetus → Baby

16. Eggs are formed in the:

(a) Testes

(b) Penis

(c) Ovary

(d) None of these.

► (c) Ovary

17. In yeast, asexual reproduction takes place by

(a) Cutting

(b) Vegetative reproduction

(c) Budding

(d) Binary fission

► (c) Budding

18. Tadpole is the developing stage of:

(a) Dogs

(b) Cats

(c) Frogs

(d) Human

► (c) Frogs

19. The age between 13 years to 19 years is called

(a) Adult age

(b) Teenage

(c) Child age

(d) Growth age

► (b) Teenage

20. Which of the following can prevent sexually transmitted disease?

(a) Oral contraceptives

(b) Vasectomy

(c) Condom

(d) Veginal pills

► (c) Condom

21. The modes of reproduction in animals are

(a) Only one type

(b) Two types

(c) Three types

(d) Four types

► (b) Two types

22. How are Paramecium and Amoeba are similar?

(a) Unicellular.

(b) Does not have a nucleus.

(c) Reproduces by binary fission.

(d) Both (A) and (C)

► (d) Both (A) and (C)

23. Which of these organisms reproduce in the same way as yeast?

(a) Hydra                         

(b) Amoeba          

(c) Starfish                        

(d) Flatworm

► (a) Hydra                         

24. During mitosis

(a) One cell enlarge into one cell

(b) One cell divide into two cells

(c) One cell divide into four cells

(d) One cells divide into eight cells

► (b) One cell divide into two cells

Class 8 Science Chapter 9 Extra Questions and Answers Reproduction in Animals

Extra Questions for Class 8 Science Chapter 9 Reproduction in Animals with Answers Solutions

Reproduction in Animals Class 8 Extra Questions Very Short Answer Type

Question 1.
What is reproduction?
Answer:
Reproduction is the biological process by which new individual organisms are produced from their parents.

Question 2.
What is sexual reproduction?
Answer:
Reproduction which involves the fusion of male and female gametes is known as sexual reproduction.

Question 3.
What is fertilisation?
Answer:
The fusion of ova and sperm is called fertilisation.

Question 4.
What is a fertilised egg called?
Answer:
Zygote

Question 5.
What is asexual reproduction?
Answer:
The mode of reproduction in which only a single parent is involved.

Question 6.
Which mode of reproduction does take place in human beings?
Answer:
Sexual reproduction

Question 7.
How many partners involve in sexual reproduction?
Answer:
Two (Parents)

Question 8.
Name two animals in which asexual reproduction takes place.
Answer:
Hydra and yeast

Question 9.
Name the reproductive organs of male.
Answer:
A pair of testes, two spermducts and a penis.

Question 10.
Name the reproductive organs of female.
Answer:
A pair of ovaries, oviducts and uterus.

Question 11.
Name the modes of reproduction.
Answer:

• Sexual reproduction
• Asexual reproduction.

Question 12.
What is male gamete or sperm?
Answer:
The reproductive cell produced by male reproductive organs is called male gamete or sperm.

Question 13.
What is female gamete or ova?
Answer:
The reproductive cell produced by female reproductive organs is called female gamete or ova.

Question 14.
Which organ produces eggs or ovum?
Answer:
A pair of ovary.

Question 15.
Name the male gamete.
Answer:
Sperm

Question 16.
Name the female gamete.
Answer:
Ova or egg

Question 17.
Which male reproductive organ produces sperm?
Answer:
A pair of testes.

Question 18.
In which organ fertilisation take place in female?
Answer:
Fallopian tube

Question 19.
What are the two methods of asexual reproduction?
Answer:

• Budding
• Binary fission

Question 20.
Name two animals which undergo external fertilisation.
Answer:
Frog and fish

Question 21.
Name two animals which undergo internal fertilisation.
Answer:
Human being and cow

Question 22.
Which type of reproduction takes place in Amoeba?
Answer:
Asexual reproduction through binary fission.

Question 23.
What type of reproduction is cloning?
Answer:
Asexual reproduction

Question 24.
What is foetus?
Answer:
Foetus is a well developed embryo.

Question 25.
What is IVF technique of reproduction?
Answer:
It is fertilisation outside the body.

Question 26.
Give the full form of IVF.
Answer:
In vitro Fertilisation.

Question 27.
How are test tube babies born?
Answer:
Test tube babies are born through IVF technique.

Question 28.
What is cloning?
Answer:
Cloning is the production of exact copy of a part of or whole living body.

MCQ Questions for Class 8 Science: Ch 8 Cell Structure and Functions

1.Which of the following cells can change its shape

(a) White blood cell

(b) Egg cell

(c) Red blood cell

(d) All of the above

► (a) White blood cell

2. What are pseudopodia?

(a) Eye of amoeba

(b) False feet of amoeba

(c) Heart of amoeba

(d) Vacuole of amoeba

► (b) False feet of amoeba

3. Vacuoles of plant cells are

(a) permanent

(b) semi-permanent

(c) temporary

(d) impermeable

► (a) permanent

4. Tissue is a       

(a) Group of organs       

(b) Group of cells       

(c) Group of tissues       

(d) Group of organisms

► (b) Group of cells       

5. Which of the following is a saclike structure that store food, wastes and water?

(a) Lysosomes

(b) Centrosomes

(c) Chromosomes

(d) Vacuoles

► (d) Vacuoles

6. Which of the following is absent in an animal cell?

(a) Cytoplasm

(b) Nucleus

(c) Cell membrane

(d) Cell wall

► (d) Cell wall

7. Which of the following given below is in the ascending order of the number of nuclei present in cells?

(a) Paramoecium, brain cell, RBC of mammals.

(b) RBC of mammals, brain cell, paramoecium.

(c) Brain cell, RBC of mammals, paramoecium.

(d) All of these

► (b) RBC of mammals, brain cell, paramoecium.

8. Power house of the cell is :

(a) mitochondria

(b) chloroplast

(c) ribosome

(d) nucleus

► (a) mitochondria

9. Which of the following tissues include blood cell?

(a) Epithelial tissue

(b) Muscle tissue

(c) Connective tissue

(d) Nervous tissue

► (c) Connective tissue

10. Which type of tissues support, defend and store food in animals?

(a) Epithelial

(b) Connective

(c) Nervous

(d) Muscular

► (b) Connective

11. Membrane of nucleus is porous so it :

(a) allows movement of chromosomes out of nucleus

(b) allows exchange of cell organelles

(c) allows transport of specific proteins

(d) allows leakage of genes into cytoplasm

► (c) allows transport of specific proteins

12. Thread like structures present inside nucleus are :

(a) chromosomes

(b) ribosomes

(c) lysosomes

(d) all of them

► (a) chromosomes

13. Identify the statement which is true for cells.

(a) Cells can be easily seen with naked eyes.

(b) Insect’s egg is not a cell.

(c) A single cell can perform all the functions in a unicellular organism.

(d) The size and shape of cells is uniform in multicellular organisms

► (c) A single cell can perform all the functions in a unicellular organism.

14. Cell wall of bacteria contains :

(a) phospholipid

(b) ribonucleic acid

(c) peptidoglycan

(d) deoxyribonucleic acid

► (c) peptidoglycan

15. If your father has brown eyes, you may also have brown eyes. If your mother has curly hair, you might also end up having curly hair. This transfer of characteristics is due to the transfer of ______.

(a) Mitochondria

(b) Chromosomes

(c) Lysosomes

(d) Chloroplasts

► (b) Chromosomes

16. Which of the following is the control room of the cell?

(a) Nucleus

(b) Protoplasm

(c) Chloroplast

(d) Ribosome

► (a) Nucleus

17. Which of the following is a locomotory organelle in protozoa ?

(a) pseudocoelom

(b) tentacles

(c) flagella

(d) all of them

► (c) flagella

18. Which of the following components is/ are present in the nervous system?

(a) Brain

(b) Spinal cord

(c) Cranial and spinal nerves

(d) All of these

► (d) All of these

19. Cell membrane is also called:

(a) cell wall

(b) nucleolus

(c) cytoplasm

(d) Plasma membrane 

► (d) Plasma membrane 

20. The power house of cell is called

(a) Cell wall

(b) Mitochondria

(c) Ribosomes       

(d) Nucleus

► (b) Mitochondria

21. Which of the following statements is/are the functions of golgi apparatus?

(a) Transporting proteins that are to be released from the cell

(b) Packaging proteins into vesicles.

(c) Altering or modifying proteins.

(d) All of these

► (b) Packaging proteins into vesicles.

22. Single celled organisms are called

(a) Unicellular

(b) Multicellular

(c) Both of these

(d) None of these

► (a) Unicellular

23. The plastid responsible for fruit colour is :

(a) chromoplast

(b) amyloplast

(c) chloroplast

(d) leucoplast

► (a) chromoplast

24. Cell is discovered by

(a) Robert Brown

(b) Robert Hooke

(c) John Mendal

(d) Charles Darwin

► (b) Robert Hooke

25. Which of the following is selectively permeable?

(a) cell membrane

(b) cell wall

(c) plasmid membrane

(d) capsule

► (a) cell membrane

Class 8 Science Chapter 8 Extra Questions and Answers Cell Structure and Functions

Extra Questions for Class 8 Science Chapter 8 Cell Structure and Functions with Answers Solutions

Cell Structure and Functions Class 8 Extra Questions Very Short Answer Type

Question 1.
What is the basic, functional and structural unit of life?
Answer:
Cell

Question 2.
Which cell does not have nucleus?
Answer:
Red blood cell

Question 3.
What is the name of the organism which can be seen only with the help of microscope?
Answer:
Microorganisms

Question 4.
What are the organisms which are composed of many cells packed together called?
Answer:
Multicellular organisms

Question 5.
What is the name of the power house of the cell?
Answer:
Mitochondria

Question 6.
Name one example of prokaryotic cell.
Answer:
Blue-green algae

Question 7.
Amoeba and Paramecium belong to which category of organisms?
Answer:
Unicellular

Question 8.
Which instrument is used to observe cells?
Answer:
Micrbscope

Question 9.
Why we do not sense any pain when we cut nails and hair?
Answer:
Nails and hair are made up of dead cells.

Question 10.
What is the name of living substance present in cell?
Answer:
Protoplasm

Question 11.
What is the other name of cell membrane?
Answer:
Plasma membrane

Question 12.
What is the name of thread-like structure present in nucleoplasm?
Answer:
Chromatin

Question 13.
What is the name of cell which has a well-defined nucleus?
Answer:
Eukaryotic cell

Question 14.
Name the two types of cell.
Answer:
Prokaryotic cells and eukaryotic cells.

Cell Structure and Functions Class 8 Extra Questions Short Answer Type

Question 1.
What is the function of cell wall?
Answer:
Cell wall is a tough, rigid layer that surrounds some types of cells (plants and some bacterial cells). The major function of the cell wall is to provide rigidity, tensile strength, structural support, protection against mechanical stress and infection.

Question 2.
Name the parts of the nucleus and state its function.
Answer:
Nucleus consists of three main parts nuclear membrane, nucleoplasm and nucleolus. Nucleus plays an important role during cell division. It also controls the activities of the cell.

Question 3.
What is an organ?
Answer:
The structure that contains more than one type of tissues and is visible to the naked eyes are called organs.

Question 4.
What do you mean by unicellular and multicellular organisms?
Answer:
Organisms which consists of only one cell are called unicellular organisms while the organisms made up of more than one cell are called multicellular organisms.

Question 5.
Give a brief description of nucleus.
Answer:
Nucleus is a dense round body found in the centre of an animal cell and mostly on the periphery of the plant cell. The nucleus controls all the activities in a cell.

h

Question 6.
Name the following:
(i) Controls the function of a cell.
(ii) Selectively allows things to get in and out of the cell.
(iii) Transfer characters from parents to offsprings.
Answer:
(i) Nucleus
(ii) Cell membrane
(iii) Genes

Question 7.
What is nucleolus?
Answer:
A spherical body present at the centre of the nucleus is called the nucleolus.

Question 8.
What is endoplasmic reticulum?
Answer:
It is the system of complex folded network of membranous tubes which connects nuclear membrane with the plasma membrane. They allow movement of substances within the cell.

Question 9.
What are cell organelles?
Answer:
The tiny components present in the cytoplasm are called cell organelles.

Question 10.
What is cell membrane?
Answer:
The thin and delicate membrane surrounding the cell cytoplasm is called cell membrane.

MCQ Questions for Class 8 Science: Ch 7 Conservation of Plants and Animals

1. Ill effect of deforestation is it

(a) Increases temperature of earth

(b) Increases pollution level

(c) Increases CO₂ level of atmosphere

(d) All of the above

► (d) All of the above

2. Which of the following is an abiotic component?
(a) Cow
(b) Grass
(c) Temperature
(d) Bacteria
► (c) Temperature

3. The place of living of an organism in environment is called:

(a) Home

(b) Resort

(c) Habitat

(d) Reservoir

► (c) Habitat

4. The species which are at the verge of the extinction are called:

(a) Endemic

(b) Extinct

(c) Endangered

(d) None of these

► (c) Endangered

5. Which of the following are the effects of the mismanagement of timber logging?

(a) Floods

(b) Soil erosion

(c) Aforestation

(d) Both (A) and (B)

► (d) Both (A) and (B)

6. Which of the following is/are caused due to uncontrolled deforestation?

(a) The destruction of habitats

(b) Landslides

(c) Floods

(d) All of these

► (d) All of these

7. Deforestation takes place:

(a) Only by human activities

(b) Only by natural reasons.

(c) Both of these

(d) None of these

► (c) Both of these

8. Our biosphere is made up of various ecosystems. All ecosystems are:

(a) inter related

(b) inter connected

(c) intraspecific

(d) both inter connected & inter related

► (d) both inter connected & inter related

9. What is the variety of life and the diversity of genes, species and ecosystems of a region and their inter connectedness called?

(a) Biosphere

(b) Biodiversity

(c) Bioconservation

(d) Biocommunity

► (b) Biodiversity

10. Species is a group of population capable of :

(a) interequilibrium

(b) interfeeding

(c) intercommunication

(d) interbreeding

► (d) interbreeding

11. A place in environment where an organism lives is ________

(a) Home

(b) Resort

(c) Habitat

(d) Reservoir

► (c) Habitat

12. Finest teak of India is obtained from :

(a) Forests of Kaziranga national park

(b) Forests of Satpura

(c) Sunderbans

(d) Forests of Kanha national park

► (b) Forests of Satpura

13. Which of the following is/are advantage(s) of forests?

(a) Forests provide us with oxygen.

(b) They protect soil and provide habitat to a large number of animals.

(c) They help in bringing good rainfall in neighboring areas.

(d) All of these

► (d) All of these

14. Cutting of a forest at a large scale is called:

(a) Deforestation

(b) Reforestation.

(c) Afforestation

(d) All of these.

► (a) Deforestation

15. Those species which exist in small numbers are called:

(a) extinct species

(b) rare species

(c) few species

(d) indeterminate species

► (b) rare species

16. Which of the following are the uses of IUCN Red List?

(a) Developing awareness about the importance of threatened biodiversity

(b) Identification and documentation of endangered species

(c) Providing a global index of the decline of biodiversity

(d) All of these

► (d) All of these

17. Fauna indicates for

(a) Plants

(b) Animals

(c) Both plants and animals

(d) None of these

► (b) Animals

18. The growing of more and more plants is called:

(a) Deforestation

(b) Reforestation

(c) Both of these

(d) None of these

► (b) Reforestation

19. Term biodiversity was coined by:

(a) Haeckal

(b) Wilson

(c) Stanley

(d) Diener

► (b) Wilson

20. A sustainable functional unit of biosphere is called:

(a) Ecology

(b) Ecomodem

(c) Ecosystem

(d) Ecomism

► (c) Ecosystem

21. Which of the following are living resources in nature?

(a) Flora

(b) Fauna

(c) Soil

(d) Both (A) and (B)

► (d) Both (A) and (B)

22. Which of the following shows a modern technology measure that helps preserve and conserve the environment?

(a) The practising crop rotation

(b) The recycling of paper, plastics and metal cans

(c) Using machines in agricultural industry

(d) Converting industrial wastes into biogas

► (b) The recycling of paper, plastics and metal cans

23. The first reserve forest of India is :

(a) Jim Corbett national park

(b) Sunderbans

(c) Satpura national park

(d) Eastern Ghats

► (c) Satpura national park

24. What is the main aim of conserving living organisms?

(a) To increase the world’s population of organisms

(b) To prevent the extinction of endangered species

(c) To help the students of botany and zoology

(d) To help in ecotourism

► (b) To prevent the extinction of endangered species

25. The variety of animals, plants and microbes found in a particular area constitutes that area

(a) Biostatistics

(b) Biomagnification

(c) Biovariety

(d) Biodiversity

► (d) Biodiversity

26. Biotic components of an ecosystem does not include :

(a) Minerals

(b) Mammals

(c) Mosses

(d) Microbes

► (a) Minerals

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

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

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

Question 1.
What is sanctuary?
Answer:
An area where animals are protected from any disturbance to them and their habitat is called a – sanctuary.

Question 2.
Name the major threat to the survival of organism.
Answer:
Deforestation

Question 3.
Write the names of some parks and sanctuaries.
Answer:
Dudhwa National Park, Bharatpur Bird Sanctuary, Kaziranga National Park, Nelapattu Bird Sanctuary, etc.

Question 4.
Write two natural causes of deforestation.
Answer:

• Severe droughts
• Forest fires

Question 5.
Give examples of flora.
Answer:
Teak, sal, mango, jamun, arjun, etc.

Question 6.
Give examples of fauna.
Answer:
Elephant, tiger, wild bear, etc.

Question 7.
Name two endemic fauna.
Answer:
Giant squirrel, bison

Question 8.
Name some forest products.
Answer:
Paper, wood, timber, vegetables, fruits, rubber, etc.

Question 9.
What is the name of the reserved land used to protect biodiversity?
Answer:
Biosphere Reserve

Question 10.
Name the first Reserve Forest of India.
Answer:
Satpura National Park

Question 11.
Name products obtained from animals for which they are hunted.
Answer:
Skin, fur, horn, eggs, flesh, etc.

Question 12.
Does soil erosion affect the fertility of soil?
Answer:
Yes

Question 13.
List the names of some migratory birds.
Answer:

• Siberian crane
• Bar-headed goose
• Arctic tern
• Surkhab

Question 14.
Write the names of some extinct animals.
Answer:
Dodo, dinosaurs, mammoth, etc.

Question 15.
When was Project Tiger launched?
Answer:
April 1,1973

Question 16.
How many rock shelters are there in Pachmarhi Biosphere Reserve?
Answer:
55

Question 17.
Name two wildlife sanctuaries present in Pachmarhi Biosphere Reserve.
Answer:
Pachmarhi, Bori

Question 18.
What is the plantation of new plants called?
Answer:
Reforestation

Question 19.
What is a zoo?
Answer:
A place where animals receive protection is called a zoo.

Question 20.
Name one reason owing to which birds migrate.
Answer:
For breeding

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

Question 1.
What do you mean by deforestation?
Answer:
The cutting of trees on a large scale is called deforestation.

Question 2.
Define national park.
Answer:
A national park is an area reserved for wildlife where they can freely use the habitats and natural resources.

Question 3.
What are flora?
Answer:
The plant species found in a particular area are called flora.

Question 4.
What are fauna?
Answer:
The animal species found in a particular area are called fauna.

Question 5.
What do you mean by species?
Answer:
Species is a group of population which are capable of interbreeding.

Question 6.
What is Satpura Tiger Reserve?
Answer:
It is a Project Tiger which was launched by the government in the country to protect the tigers.

Question 7.
What are endangered animals?
Answer:
The animals whose numbers are diminishing to such a level that they might face extinction are known as ‘endangered animals.’

Question 8.
Define ‘Red Data Book.’
Answer:
A book that keeps records of all the endangered plant and animal species is called a Red Data Book.

Question 9.
Define migratory birds.
Answer:
The birds which cover long distances to reach another land for some reasons are known as migratory birds.

Question 10.
Mention the causes of deforestation.
Answer:
The cause of deforestation could be:

• Forest fires
• Building houses, factories
• Severe droughts
• Using wood for some purposes
• Human encroachment and procuring land for cultivation

Question 11.
What do you mean by desertification?
Answer:
The conversion of fertile land into deserts is called desertification.

Question 12.
What is biodiversity?
Answer:
The diversity of plant and animal life in a particular habitat (or in the world as a whole) is called bio-diversity.

Question 13.
Define biosphere.
Answer:
Biosphere is that part of the earth in which living organisms exist or which supports biological diver-sity.

Question 14.
Define endemic species.
Answer:
The species of plants and animals which are found exclusively in a particular area are called endemic species.

Question 15.
Explain the term ecosystem.
Answer:
Ecosystem is a system formed by the interaction of a community of organisms with their physical environment.