All Exams >
Class 8 >
Online Quizzes for Class 8 >
All Questions
All questions of Science for Class 8 Exam
Which of the following tools would a farmer use to remove weeds from the field?
- a)Hoe
- b)Axe
- c)Plough
- d)Cultivator
Correct answer is option 'A'. Can you explain this answer?
Which of the following tools would a farmer use to remove weeds from the field?
a)
Hoe
b)
Axe
c)
Plough
d)
Cultivator
|
Aditya Shah answered |
Option A: Hoe is used to remove weeds and to loosen the soil. Hoe works like a blade. Below is the image of Hoe.
Option B: Axe is used to cut the trees.
Option C: Plough is used for tilling the soil.
Option D: The cultivator is used for ploughing.
Option C: Plough is used for tilling the soil.
Option D: The cultivator is used for ploughing.
Thus, option A is correct.
Cutting mature crop manually or by a machine is called:
- a)Irrigating
- b)Harvesting
- c)Breeding
- d)Weeding
Correct answer is option 'B'. Can you explain this answer?
Cutting mature crop manually or by a machine is called:
a)
Irrigating
b)
Harvesting
c)
Breeding
d)
Weeding
|
|
Anita Menon answered |
The process of cutting the mature crop manually or by machine is called harvesting. The crops are pulled out or cut close to the ground.
S.I. unit of pressure is- a)Celsius
- b)Newton
- c)Kelvin
- d)Pascal
Correct answer is option 'D'. Can you explain this answer?
S.I. unit of pressure is
a)
Celsius
b)
Newton
c)
Kelvin
d)
Pascal
|
|
Saranya Nair answered |
S.I. unit of pressure is Pascal. One Pascal is equal to one Newton per meter square.
Coke contains approximately _____ carbon.
- a)98 percent
- b)95 percent
- c)90 percent
- d)99 percent
Correct answer is option 'D'. Can you explain this answer?
Coke contains approximately _____ carbon.
a)
98 percent
b)
95 percent
c)
90 percent
d)
99 percent
|
|
Ananya Das answered |
Coke is obtained from destructive distillation of coal. Coke contains approximately 99% carbon. It is used in blast furnace.
Weeds are the:- a)main crop plants
- b)insects and pests
- c)unwanted plants growing along the crop
- d)chemical substances.
Correct answer is option 'C'. Can you explain this answer?
Weeds are the:
a)
main crop plants
b)
insects and pests
c)
unwanted plants growing along the crop
d)
chemical substances.
|
Ritu Joshi answered |
A weed is a plant growing in the 'wrong' place; where it is not wanted or where it causes harm. A weed in a garden may make the garden look untidy and it may shade out or strangle garden plants. A weed in the New Zealand environment may exclude native species, change the environment to make it less suitable to native animals or impact on the farming economy.
The first agricultural task is the sowing of seeds. - a)True
- b)False
Correct answer is option 'B'. Can you explain this answer?
The first agricultural task is the sowing of seeds.
a)
True
b)
False
|
Bhakti Mehta answered |
The first agricultural task is Preparation of soil. Therefore, Sowing of seeds is not the first agricultural task.
Option (b)
Sound is produced by- a)Heating
- b)Moving
- c)Cooling
- d)Vibration
Correct answer is option 'D'. Can you explain this answer?
Sound is produced by
a)
Heating
b)
Moving
c)
Cooling
d)
Vibration
|
Dhruv Gupta answered |
Sound is produced by vibration of object. Vibration creates disturbance in medium which reaches to observer ear through air, water or solid medium.
In ancient cultures, process of separating grains from chaff is :- a)Buffering
- b)Harvesting
- c)Wind Winnowing
- d)None of these
Correct answer is option 'C'. Can you explain this answer?
In ancient cultures, process of separating grains from chaff is :
a)
Buffering
b)
Harvesting
c)
Wind Winnowing
d)
None of these
|
Akshita Bose answered |
Wind winnowing is an agricultural method developed by ancient cultures for separating grain from chaff. It is also used to remove hay and chaff or other pests from stored grain.
A water tank has four taps fixed at points A, B, C, D as shown in Fig. 11.4. The water will flow out at the same pressure from taps at
- a)A and B
- b)C and D
- c)B and C
- d)A and C
Correct answer is option 'C'. Can you explain this answer?
A water tank has four taps fixed at points A, B, C, D as shown in Fig. 11.4. The water will flow out at the same pressure from taps at
a)
A and B
b)
C and D
c)
B and C
d)
A and C
|
Raghavi Iyer answered |
As we know liquids exert equal pressure at the same depth.
From the figure, B and C are at the same level, hence pressure will be the same at B and C.
From the figure, B and C are at the same level, hence pressure will be the same at B and C.
Any plant cultivated at a large stretch of land is called :- a)crop
- b)weed
- c)cereal
- d)fibre
Correct answer is option 'A'. Can you explain this answer?
Any plant cultivated at a large stretch of land is called :
a)
crop
b)
weed
c)
cereal
d)
fibre
|
Rohini Seth answered |
When plants of the same kind are grown and cultivated in one place on large scale, it is called a crop.
Example: Crop of wheat, crop of rice, etc.
Example: Crop of wheat, crop of rice, etc.
Which fuels are used for running automobiles?- a)Wood
- b)Coal
- c) Diesel
- d)Charcoal
Correct answer is option 'C'. Can you explain this answer?
Which fuels are used for running automobiles?
a)
Wood
b)
Coal
c)
Diesel
d)
Charcoal
|
|
Amit Kumar answered |
Diesel is more combustible than these fuels,it releases energy rapidly.
Which of the following disease is spread due to bacteria?- a)Measles
- b)Tuberculosis
- c)Chicken pox
- d)Polio
Correct answer is option 'B'. Can you explain this answer?
Which of the following disease is spread due to bacteria?
a)
Measles
b)
Tuberculosis
c)
Chicken pox
d)
Polio
|
|
Bhargavi Dasgupta answered |
Explanation:
Tuberculosis:
- Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis.
- It primarily affects the lungs but can also affect other parts of the body.
- The disease is spread through the air when an infected person coughs or sneezes, releasing bacteria into the air.
- People nearby can then breathe in these bacteria and become infected.
- Tuberculosis is a highly contagious disease, especially in crowded or poorly ventilated environments.
- Symptoms of tuberculosis include coughing, chest pain, weight loss, fatigue, and fever.
- Treatment usually involves a combination of antibiotics taken over several months to kill the bacteria in the body.
- Without treatment, tuberculosis can be deadly, but with proper medical intervention, most people can be cured.
Therefore, tuberculosis is the correct answer as it is a disease spread due to bacteria.
Microorganisms can be seen with naked eyes.- a)True
- b)False
Correct answer is option 'B'. Can you explain this answer?
Microorganisms can be seen with naked eyes.
a)
True
b)
False
|
Geetika Shah answered |
B is the correct option.Microbes are minute, unicellular organisms that are invisible to the naked eye. They are also known as microorganisms or microscopic organisms as they could only be seen under a microscope or magnifying glass.
What is the name of object through which light can pass?- a)Opaque
- b)Translucent
- c)Transparent
- d)Luminous
Correct answer is option 'C'. Can you explain this answer?
What is the name of object through which light can pass?
a)
Opaque
b)
Translucent
c)
Transparent
d)
Luminous
|
Sanaya Shah answered |
The object through which light can pass easily is called transparent object. Glass, water and thin plastic sheets are transparent object.
SI unit of the calorific value of a fuel is :-a) KJ/kgb) KW/kgc) N/kgd) KJ/gCorrect answer is option 'A'. Can you explain this answer?
|
|
Rohit Sharma answered |
Calorific value provides the amount of energy that is released when a fuel or material undergoes the process of combustion.
It is usually a measure of energy.
The SI unit (international system of units) of calorific value is Joule/Kg or Kilo Joule/Kg.
In asexual reproduction- a)No parents are involved
- b)Four parents are involved
- c)One parent is involved
- d)Two parents are involved
Correct answer is option 'C'. Can you explain this answer?
In asexual reproduction
a)
No parents are involved
b)
Four parents are involved
c)
One parent is involved
d)
Two parents are involved
|
|
Disha Dey answered |
In asexual reproduction only one parent is involved. The new organism is identical to parent. No gametes formation takes place in asexual reproduction.
Seed drill is used to remove grains from chaff.- a)True
- b)False
Correct answer is option 'B'. Can you explain this answer?
Seed drill is used to remove grains from chaff.
a)
True
b)
False
|
Shubham Sharma answered |
Seed drill is for drilling the seeds or actually sowing seeds not removing seeds.
Winowing is used for this process.
The shape of an aeroplane is like a- a)Bird
- b)Car
- c)Dog
- d)All.
Correct answer is option 'A'. Can you explain this answer?
The shape of an aeroplane is like a
a)
Bird
b)
Car
c)
Dog
d)
All.
|
Vivek Rana answered |
Airplanes have wings, just like birds. They also have a light Skelton to decrease their weight, and they have a streamlined shape to decrease drag. Airplanes wings are designed to create lift by changing the pressure, rather than by flapping them up and down.
There are__ __ pairs of chromosome in human cell. - a)23
- b)46
- c)22
- d)All are wrong
Correct answer is option 'A'. Can you explain this answer?
There are__ __ pairs of chromosome in human cell.
a)
23
b)
46
c)
22
d)
All are wrong
|
Subset Academy answered |
In human cells, there are 23 pairs of chromosomes. Here's a concise explanation:
- Humans typically have 23 pairs of chromosomes, totaling 46 chromosomes.
- Each parent contributes one set of 23 chromosomes, including one sex chromosome pair.
- Chromosomes contain genetic material that carries information crucial for traits and functions.
- This chromosomal arrangement is essential for genetic diversity and proper cell function in humans.
- Humans typically have 23 pairs of chromosomes, totaling 46 chromosomes.
- Each parent contributes one set of 23 chromosomes, including one sex chromosome pair.
- Chromosomes contain genetic material that carries information crucial for traits and functions.
- This chromosomal arrangement is essential for genetic diversity and proper cell function in humans.
The monsoon season in India is during the months:
- a)April to December
- b)June to September
- c)November to March
- d)January to May
Correct answer is option 'B'. Can you explain this answer?
The monsoon season in India is during the months:
a)
April to December
b)
June to September
c)
November to March
d)
January to May
|
|
Amit Sharma answered |
Monsoon or rainy season, lasting from June to September. The season is dominated by the humid southwest summer monsoon, which slowly sweeps across the country beginning in late May or early June. Monsoon rains begin to recede from North India at the beginning of October. South India typically receives more rainfall.
Glands without ducts- a)Mammary gland
- b)Exocrine gland
- c)Endocrine glands
- d)Pancreatic gland
Correct answer is option 'C'. Can you explain this answer?
Glands without ducts
a)
Mammary gland
b)
Exocrine gland
c)
Endocrine glands
d)
Pancreatic gland
|
|
Ananya Das answered |
The glands without ducts are called ductless gland. Endocrine glands are ductless gland as they deliver the hormone to target site through blood.
Conversion of dead trees and other plants into coal is called :- a)Carbonisation
- b)refining
- c)destructive distillation
- d)decarbonisation
Correct answer is 'A'. Can you explain this answer?
Conversion of dead trees and other plants into coal is called :
a)
Carbonisation
b)
refining
c)
destructive distillation
d)
decarbonisation
|
Meera Yadav answered |
Carbonisation
Carbonisation is the conversion of dead trees and other plants into coal. It is a process that occurs over millions of years and involves the transformation of organic matter into a dense, black, carbon-rich substance through a series of chemical and physical changes.
Process of Carbonisation
The process of carbonisation involves the following steps:
1. Formation of Peat: Dead trees, leaves, and other plant material accumulate in wetlands and bogs, where they are slowly decomposed by bacteria and other microorganisms. As this material accumulates, it forms a layer of peat, which is a soft, spongy material that is rich in organic matter.
2. Formation of Lignite: Over time, the weight of the overlying sediment and water causes the peat to become compacted and compressed. As this happens, the water is squeezed out of the peat, and the organic matter is transformed into a soft, brown substance called lignite.
3. Formation of Bituminous Coal: With increasing heat and pressure, the lignite is further transformed into a harder, black substance called bituminous coal. This is the most common type of coal found in the world.
4. Formation of Anthracite Coal: At even higher temperatures and pressures, bituminous coal is transformed into a hard, dense, black substance called anthracite coal. This is the highest quality coal and has the highest carbon content.
Uses of Coal
Coal is an important source of energy and is used for a variety of purposes, including:
1. Electricity generation: Coal is burned to produce steam, which is used to generate electricity.
2. Steel production: Coal is used as a fuel and as a reducing agent in the production of steel.
3. Cement production: Coal is used as a fuel in the production of cement.
4. Heating: Coal is used as a fuel for heating homes and buildings.
Conclusion
Carbonisation is the process by which dead trees and other plants are converted into coal. It is a slow process that occurs over millions of years and involves the transformation of organic matter into a dense, black, carbon-rich substance through a series of chemical and physical changes. Coal is an important source of energy and is used for a variety of purposes, including electricity generation, steel production, cement production, and heating.
Carbonisation is the conversion of dead trees and other plants into coal. It is a process that occurs over millions of years and involves the transformation of organic matter into a dense, black, carbon-rich substance through a series of chemical and physical changes.
Process of Carbonisation
The process of carbonisation involves the following steps:
1. Formation of Peat: Dead trees, leaves, and other plant material accumulate in wetlands and bogs, where they are slowly decomposed by bacteria and other microorganisms. As this material accumulates, it forms a layer of peat, which is a soft, spongy material that is rich in organic matter.
2. Formation of Lignite: Over time, the weight of the overlying sediment and water causes the peat to become compacted and compressed. As this happens, the water is squeezed out of the peat, and the organic matter is transformed into a soft, brown substance called lignite.
3. Formation of Bituminous Coal: With increasing heat and pressure, the lignite is further transformed into a harder, black substance called bituminous coal. This is the most common type of coal found in the world.
4. Formation of Anthracite Coal: At even higher temperatures and pressures, bituminous coal is transformed into a hard, dense, black substance called anthracite coal. This is the highest quality coal and has the highest carbon content.
Uses of Coal
Coal is an important source of energy and is used for a variety of purposes, including:
1. Electricity generation: Coal is burned to produce steam, which is used to generate electricity.
2. Steel production: Coal is used as a fuel and as a reducing agent in the production of steel.
3. Cement production: Coal is used as a fuel in the production of cement.
4. Heating: Coal is used as a fuel for heating homes and buildings.
Conclusion
Carbonisation is the process by which dead trees and other plants are converted into coal. It is a slow process that occurs over millions of years and involves the transformation of organic matter into a dense, black, carbon-rich substance through a series of chemical and physical changes. Coal is an important source of energy and is used for a variety of purposes, including electricity generation, steel production, cement production, and heating.
The substances which give heat and light after combustion are called- a)flame
- b)fuel
- c)combustion
- d)none of these.
Correct answer is option 'B'. Can you explain this answer?
The substances which give heat and light after combustion are called
a)
flame
b)
fuel
c)
combustion
d)
none of these.
|
|
Amit Kumar answered |
The substance which undergoes combustion is said to be combustible. It is called fuel. If a magnesium ribbon is heated,it starts burning. When a magnesium ribbon burns, it combines with the oxygen of air to form magnesium oxide, and liberates heat and light.
Separating grains from chaff is called:
- a)winnowing
- b)harvesting
- c)tilling
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
Separating grains from chaff is called:
a)
winnowing
b)
harvesting
c)
tilling
d)
None of these
|
|
Aditya Shah answered |
The process of separating grains from chaff is called as winnowing
The gas which supports combustion of coal is :- a)carbon dioxide
- b)oxygen
- c)nitrogen
- d)hydrogen
Correct answer is option 'B'. Can you explain this answer?
The gas which supports combustion of coal is :
a)
carbon dioxide
b)
oxygen
c)
nitrogen
d)
hydrogen
|
|
Ananya Das answered |
Oxygen gas supports the combustion of combustible substances including coal. Combustion of coal release carbon dioxide gas as well as solid residue.
Which of the following is an example of contact force?- a)Muscular force
- b)Gravitational force
- c)Electrostatic force
- d)Magnetic force
Correct answer is option 'A'. Can you explain this answer?
Which of the following is an example of contact force?
a)
Muscular force
b)
Gravitational force
c)
Electrostatic force
d)
Magnetic force
|
Kavya Chopra answered |
The forces in which to bodies acting on each other are in contact are called contact force. Muscular force is an example of contact force.
A combustible substance is :-
- a)wax
- b)sand
- c)water
- d)glass
Correct answer is option 'A'. Can you explain this answer?
A combustible substance is :-
a)
wax
b)
sand
c)
water
d)
glass
|
Malavika Basu answered |
A combustible substance is one that can easily catch fire and burn when exposed to heat.
-
Wax: It is a combustible substance because it can burn when ignited, which is why it is used in candles.
-
Sand: It is non-combustible, meaning it cannot catch fire or burn under normal conditions.
-
Water: It is also non-combustible, and in fact, water is commonly used to extinguish fires.
-
Glass: It is non-combustible and does not burn; instead, it melts when subjected to very high temperatures.
Therefore, wax is the correct answer as it can burn, making it a combustible substance.
Budding is found in- a)Bacteria
- b)Protozoa
- c)Planarian
- d)Hydra
Correct answer is option 'D'. Can you explain this answer?
Budding is found in
a)
Bacteria
b)
Protozoa
c)
Planarian
d)
Hydra
|
Pankaj Unni answered |
Budding is a mode of asexual reproduction in which a small outgrowth develop on body surface that enlarge and get separated from parent body. Budding takes place in hydra and yeast.
Fluids are only liquids.- a)True
- b)False
Correct answer is option 'B'. Can you explain this answer?
Fluids are only liquids.
a)
True
b)
False
|
Kavya Saxena answered |
A fluid is a substance that continually flows under an applied shear stress, or external force. Fluids are a phase of matter and include liquids, gases and plasmas.
Sliding friction is ______________ than static friction.- a)More
- b)Equal
- c)Greater
- d)Less
Correct answer is option 'D'. Can you explain this answer?
Sliding friction is ______________ than static friction.
a)
More
b)
Equal
c)
Greater
d)
Less
|
|
Amit Sharma answered |
- Friction comes into play when irregularities present in the surfaces of two objects in contact get interlocked with each other.
- In sliding, the time given for interlocking is very small. Hence, the interlocking is not strong.
- Therefore, less force is required to overcome this interlocking. Because of this reason, sliding friction is less than static friction.
Electricity shows magnetic effect
- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
Electricity shows magnetic effect
a)
True
b)
False
|
Chavi answered |
True to check this you can take a compass near a circuit and it will deflect this proves magnetic effect of current.
deflection of compass needle proves magnetic effect of current.
deflection of compass needle proves magnetic effect of current.
Which irrigation system is most suitable for uneven land with insufficient water availability?- a)Drip system
- b)Flood irrigation
- c)Sprinkler system
- d)Furrow irrigation
Correct answer is option 'C'. Can you explain this answer?
a)
Drip system
b)
Flood irrigation
c)
Sprinkler system
d)
Furrow irrigation
|
Divey Sethi answered |
The sprinkler system is ideal for uneven land with insufficient water availability because it mimics rainfall by dispersing water through rotating nozzles. This method ensures even distribution of water across various terrains and is effective for areas where water resources are limited.
Substance that burns in oxygen to produce heat and light is called :- a)renewable
- b)non combustible
- c)combustible
- d)limitless
Correct answer is option 'C'. Can you explain this answer?
Substance that burns in oxygen to produce heat and light is called :
a)
renewable
b)
non combustible
c)
combustible
d)
limitless
|
|
Amita Verma answered |
A chemical process in which a substance reacts with oxygen to give off heat is called combustion. The substance that undergoes combustion is said to be combustible. It is also called a fuel. The fuel may be solid, liquid or gas. Sometimes, light is also given off during combustion, either as a flame or as a glow.
Example: wood, coal, charcoal, kerosene, petrol,diesel, liquefied petroleum gas (LPG), compressednatural gas (CNG) etc.
Soil erosion may lead to :- a)water logging
- b)water scarcity
- c)air pollution
- d)floods
Correct answer is option 'D'. Can you explain this answer?
Soil erosion may lead to :
a)
water logging
b)
water scarcity
c)
air pollution
d)
floods
|
Dipika Mukherjee answered |
The removal of top fertile layer of soil is called soil erosion. Soil erosion may leads to floods.
What is the length of vocal cords in men?- a)15mm
- b)20mm
- c)5mm
- d)10mm
Correct answer is option 'B'. Can you explain this answer?
What is the length of vocal cords in men?
a)
15mm
b)
20mm
c)
5mm
d)
10mm
|
|
Amit Sharma answered |
The length of the vocal chords differs in men and women, which is why there is difference in the quality of their voice. The length of the vocal chord in men is approximately 20 mm and in women it is 15 mm.
Can you explain the answer of this question below:Pitch of sound depends upon
- A:
Wavelength
- B:
Time-period
- C:
Amplitude
- D:
Frequency
The answer is d.
Pitch of sound depends upon
Wavelength
Time-period
Amplitude
Frequency
|
Sounak Sengupta answered |
The pitch of sound depends upon the frequency of the sound by the emitting source. Greater the frequency of the sound , higher will be the pitch of that sound.
Rolling friction is smaller than- a)Sliding friction
- b)Static friction
- c)Fluid friction
- d)All of the above.
Correct answer is option 'D'. Can you explain this answer?
Rolling friction is smaller than
a)
Sliding friction
b)
Static friction
c)
Fluid friction
d)
All of the above.
|
|
Malavika Basu answered |
No the correct answer is
(a) Sliding friction
Explanation: Friction is the force which resists the relative motion between two surfaces in contact.
Now, rolling friction comes into play between two surfaces, when one body rolls over the other and sliding friction comes into play when when one body slides or tends to slide over the surface of another body; it tends to reduce the relative velocity between the two surfaces during sliding. Now, if the area of contact between the two surfaces can somehow be reduced, then the effect of friction between the two surfaces will be drastically reduced.
When an object slides across the ground, it has much more surface area in direct contact with the ground, which means that the amount of friction is significantly higher. When an object rolls along the ground, only a minuscule point on the object contacts the ground at any point in time, making the stopping force much weaker.
Moreover, in sliding motion, the heights of cavities (irregularities) are to climb up which introduces the friction, while rolling friction, the heights of cavitites are to cross over which avoid the friction.
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
Correct answer is option 'C'. Can you explain this answer?
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
|
|
Krisha Shah answered |
The vibrations of object are not visible because in most of the cases amplitude of waves are very small. Amplitude is the maximum displacement from mean position.
Water works as a fire extinguisher by removing :-
- a)source of combustible substance
- b)heat
- c)oxygen
- d)both oxygen & heat
Correct answer is option 'D'. Can you explain this answer?
Water works as a fire extinguisher by removing :-
a)
source of combustible substance
b)
heat
c)
oxygen
d)
both oxygen & heat
|
|
Sarita Verma answered |
Water extinguishers work mainly by cooling (removing heat), but a dense spray of water droplets also helps to cut off oxygen.
Water cools the combustible material so that its temperature is brought below its ignition temperature. This prevents the fire from spreading. Water vapours also surround the combustible material, helping in cutting off the supply of air so that the fire is exhausted. But water cannot be used for fires involving electrical equipment and inflammable substances.
Water cools the combustible material so that its temperature is brought below its ignition temperature. This prevents the fire from spreading. Water vapours also surround the combustible material, helping in cutting off the supply of air so that the fire is exhausted. But water cannot be used for fires involving electrical equipment and inflammable substances.
Common tick fever is caused by___________.- a)Protozoan Babesia
- b)Protozoan Eimeria
- c)Bacterium Corynebacterium
- d)Tapeworm
Correct answer is option 'A'. Can you explain this answer?
Common tick fever is caused by___________.
a)
Protozoan Babesia
b)
Protozoan Eimeria
c)
Bacterium Corynebacterium
d)
Tapeworm
|
|
Vivek Rana answered |
Tick fever is a parasitic infection caused by the species Babesia.
Magnetic force is- a)Contact force
- b)Non-contact force
- c)both (a) and (b)
- d)None.
Correct answer is option 'B'. Can you explain this answer?
Magnetic force is
a)
Contact force
b)
Non-contact force
c)
both (a) and (b)
d)
None.
|
|
Amit Sharma answered |
Magnetic forces are non - contact forces; they pull or push on objects without touching them. Magnets are only attracted to a few 'magnetic' metals and not all matter.
Force is a- a)Pull
- b)Push
- c)Pull and push both
- d)None of these.
Correct answer is option 'C'. Can you explain this answer?
Force is a
a)
Pull
b)
Push
c)
Pull and push both
d)
None of these.
|
Khushi Singh answered |
If we push or pull any object we use force to push or pull it. So... Force is both push and pull.
What is the phenomenon of light bouncing back into the same medium called?- a)Reflection
- b)Refraction
- c)Dispersion
- d)Splitting
Correct answer is option 'A'. Can you explain this answer?
What is the phenomenon of light bouncing back into the same medium called?
a)
Reflection
b)
Refraction
c)
Dispersion
d)
Splitting
|
Anoushka Das answered |
The phenomenon of light in which, light is reflected or bounced back into the same medium is called reflection.
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
Correct answer is option 'D'. Can you explain this answer?
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
|
|
Kavya Saxena answered |
A polished marble surface has the least frictional force, hence a car will travel farther on a marble floor.
During lightning and thunderstorm safe place is- a)Open field
- b)Tall tree
- c)High building
- d)High pillar
Correct answer is option 'A'. Can you explain this answer?
During lightning and thunderstorm safe place is
a)
Open field
b)
Tall tree
c)
High building
d)
High pillar
|
Aditya Gusai answered |
The correct answer is A Open field.
Which of the following statements can be regarded as an advantage of seed drill?- a)Avoiding overcrowding allows plants to get sufficient sunlight and nutrients.
- b)Seed drill reduces time and labour.
- c)It ensures seeds get covered by the soil after sowing, preventing damage caused by birds.
- d)All of the above.
Correct answer is option 'D'. Can you explain this answer?
Which of the following statements can be regarded as an advantage of seed drill?
a)
Avoiding overcrowding allows plants to get sufficient sunlight and nutrients.
b)
Seed drill reduces time and labour.
c)
It ensures seeds get covered by the soil after sowing, preventing damage caused by birds.
d)
All of the above.
|
|
Shubham Sharma answered |
Nowadays, the seed drill is used for sowing with the help of tractors. This tool sows the seeds uniformly at proper distances and depths. It ensures that seeds get covered by the soil after sowing. This prevents damage caused by birds. Sowing by using a seed drill saves time and labour.
Fluid friction can be minimized by:
- a)Adding salts to fluid
- b)Increasing volume
- c)Giving suitable shape
- d)Decreasing volume
Correct answer is option 'C'. Can you explain this answer?
Fluid friction can be minimized by:
a)
Adding salts to fluid
b)
Increasing volume
c)
Giving suitable shape
d)
Decreasing volume
|
Aniket Choudhary answered |
Fluid friction can be minimized by giving suitable shapes to the objects moving in the fluids.
In human eyes, image is formed on- a)Eye lens
- b)Cornea
- c)Retina
- d)Pupil
Correct answer is option 'C'. Can you explain this answer?
In human eyes, image is formed on
a)
Eye lens
b)
Cornea
c)
Retina
d)
Pupil
|
|
Bhaskar Desai answered |
Formation of Image in Human Eye
The human eye is a complex organ that is responsible for vision. It captures the light that enters the eye and converts it into electrical impulses that are sent to the brain for interpretation. The image formation in the human eye involves the following steps:
1. Cornea:
The cornea is the transparent outer layer of the eye that covers the iris, pupil, and anterior chamber. It acts as a protective barrier and helps to refract (bend) light as it enters the eye.
2. Pupil:
The pupil is the black circular opening in the center of the iris. It controls the amount of light that enters the eye by dilating (opening up) or constricting (closing down) in response to changes in light intensity.
3. Lens:
The lens is a transparent, biconvex structure located behind the iris. It helps to focus light onto the retina by changing its shape. The process of changing the shape of the lens is called accommodation.
4. Retina:
The retina is the innermost layer of the eye that contains photoreceptor cells called rods and cones. These cells convert light into electrical impulses that are sent to the brain via the optic nerve for interpretation.
5. Optic Nerve:
The optic nerve is a bundle of nerve fibers that carries the electrical impulses from the retina to the brain.
6. Brain:
The brain receives the electrical impulses from the optic nerve and interprets them as images.
Conclusion:
Thus, the image is formed on the retina of the human eye. The cornea and lens work together to focus the light onto the retina, which contains the photoreceptor cells that convert the light into electrical impulses that are sent to the brain for interpretation.
The human eye is a complex organ that is responsible for vision. It captures the light that enters the eye and converts it into electrical impulses that are sent to the brain for interpretation. The image formation in the human eye involves the following steps:
1. Cornea:
The cornea is the transparent outer layer of the eye that covers the iris, pupil, and anterior chamber. It acts as a protective barrier and helps to refract (bend) light as it enters the eye.
2. Pupil:
The pupil is the black circular opening in the center of the iris. It controls the amount of light that enters the eye by dilating (opening up) or constricting (closing down) in response to changes in light intensity.
3. Lens:
The lens is a transparent, biconvex structure located behind the iris. It helps to focus light onto the retina by changing its shape. The process of changing the shape of the lens is called accommodation.
4. Retina:
The retina is the innermost layer of the eye that contains photoreceptor cells called rods and cones. These cells convert light into electrical impulses that are sent to the brain via the optic nerve for interpretation.
5. Optic Nerve:
The optic nerve is a bundle of nerve fibers that carries the electrical impulses from the retina to the brain.
6. Brain:
The brain receives the electrical impulses from the optic nerve and interprets them as images.
Conclusion:
Thus, the image is formed on the retina of the human eye. The cornea and lens work together to focus the light onto the retina, which contains the photoreceptor cells that convert the light into electrical impulses that are sent to the brain for interpretation.
Penicillium is a- a)Algae
- b)Fungus
- c)Bacteria
- d)Yeast.
Correct answer is option 'B'. Can you explain this answer?
Penicillium is a
a)
Algae
b)
Fungus
c)
Bacteria
d)
Yeast.
|
|
Ananya Das answered |
Penicillium ascomycetous fungi are of major importance in the natural environment as well as food and drug production. Some members of the genus produce penicillin, a molecule that is used as an antibiotic, which kills or stops the growth of certain kinds of bacteria.
Chapter doubts & questions for Science - Online Quizzes for Class 8 2025 is part of Class 8 exam preparation. The chapters have been prepared according to the Class 8 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 8 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
Chapter doubts & questions of Science - Online Quizzes for Class 8 in English & Hindi are available as part of Class 8 exam.
Download more important topics, notes, lectures and mock test series for Class 8 Exam by signing up for free.
Online Quizzes for Class 8
268 tests
|
|
© EduRev
|
Education Revolution
|
|
Signup to see your scores
go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup