Science (English Medium) Class 8th Practice Solved Model Question Paper Annual Exam 2022-23
(Question No. 1 to 10)
Question 1. The intensity of sound is determined by the ………… of vibrations.
(c) Time period
(d) None of these
Question 2. When an ebonite rod is rubbed with wool or flannel, …………… is produced.
(a) Positive charge
(b) Negative charge
(c) Both of the above
(d) Not both
Ans– negative charge.
Question 3. Which of the following is an example of a constellation?
(a) Great Bear
(b) Leo Major
(d) All of the above
Ans- All of the above.
Question 4. Which of the following is a renewable natural resource?
(c) Natural gas
Question 5. Incomplete combustion of fuel produces poisonous .................. gas.
(a) Carbon dioxide
(b) Chloro fluoro carbon
(c) Sulfur dioxide
(d) Carbon monoxide
Ans– Carbon monoxide.
Question 6. Porous soil is helpful in making the roots of plants easily.............
(a) Synthesis of food
(d) None of these
Question 7. Which of these physical quantities requires only magnitude to be expressed?
Question 8. Where is magnesium found in plants?
Question 9. The angle of incidence is equal to the angle of reflection–
(c) In special cases
Question 10. Bread or Idli puffs up because of–
(c) Growth of yeast cells
(d) Due to beating
Ans– Growth of yeast cells.
Short Answer Questions
(Question numbers 11 to 20)
Question 11. Which zone of flame do goldsmiths use to melt gold and silver and why?
Ans- To melt gold and silver, goldsmiths use the outermost zone of the flame by blowing the metal. Because the outermost zone of the flame has the highest temperature, sufficient to melt silver and gold.
Question 12. Why is it necessary to turn and hoe the soil?
Ans- By turning and plowing the soil, the nutrients come up and the plants can use these nutrients. Therefore, turning and loosening the soil is necessary for growing crops.
Question 13. When do forces act on objects?
Answer– Force is exerted on an object when we push, pull, hit it, throw it, stumble on it, etc.
Question 14. Can air, water and soil be depleted by human activities?
Ans– No, air, water and soil cannot be depleted by human activities.
Question 15. Why is it difficult to walk on a smooth or wet floor?
Ans- Proper friction is required to walk on smooth or wet floor, which we do not get. So it is difficult to walk on smooth or wet floor.
Question 16. Name the microorganisms that fix atmospheric nitrogen in the soil.
Ans– Microorganisms that fix atmospheric nitrogen in the soil are – rhizobium bacteria, bacteria present in the soil and blue-green algae.
Question 17. Petroleum is used for which purpose?
Answer– Petroleum product bitumen is used for road construction.
Question 18. Do the sounds coming from the construction site seem pleasant?
Ans– No, the noise coming from the construction site does not seem pleasant. These sounds really unpleasant.
Question 19. How are kittens and puppies born?
Ans- Kittens and puppies are born through sexual reproduction. He is born as a child. These are called Jarayuj animals.
Question 20. Copper cannot displace zinc from its salt solution. Why?
Ans- Copper is less reactive than zinc. Hence it cannot displace zinc from its salt solution. Only a more reactive metal can displace a less reactive metal.
Long Answer Type Questions
(Question numbers 21 to 24)
Question 21. Why do fish and frogs lay hundreds of eggs at once, while the hen lays only one egg at a time? explain.
Answer– Fish and frogs lay hundreds of eggs and release millions of sperms. All of these eggs do not get fertilized and they do not become a new organism. The reason for this is that the eggs and sperms are continuously affected by the movement of water, wind and rain and there are animals living in the water which feed on these eggs. Therefore, it is necessary to lay hundreds of eggs so that fertilization can take place in some of them. Apart from this, these eggs are not covered with armor and are relatively soft. That's why they are not protected while the hen's eggs are covered with shell. A layer of jelly holds the eggs together and also protects them.
Question 22. What is a weed? How can we control them?
Answer– Some unwanted plants grow along with the crop in the field, these plants are called weeds. It is necessary to remove them otherwise they hinder the growth of the crop. They can also be toxic/harmful to animals and humans. They can be controlled in the following way-
(1) They can be destroyed by plowing the field before growing the crop. They dry up and get destroyed when the field is plowed.
(2) Before flowering and seed formation, they can be removed by hand, by spade or with the help of harrow.
(3) They can be controlled by using weedicide chemicals in the fields.
Question 23. The parents want to buy a house. It has been proposed to give them one house on the side of the road and the other after leaving three lanes from the road. Which house would you suggest your parents to buy? Explain your answer.
Answer– We will propose to our parents to buy a house three lanes away from the road. Noise pollution, noise etc. in this house will be less as compared to the house built on the side of the road. Because the sound of vehicles will be heard a lot in the house built on the side of the road. This can cause health related diseases and the ability to hear will also be affected. Apart from this, air pollution will also be enough. Therefore, leaving three lanes from the road, it would be appropriate to take a house.
Question 24. How can you contribute towards maintaining greenery in your local area?
Ans– To maintain greenery in your local area, you can contribute the following–
1. By planting trees and plants in the surrounding areas.
2. By running an awareness campaign.
3. By organizing Van Mahotsav.
4. By gifting saplings on the occasion of birthday, marriage etc.
5. By giving information about plants available to humans free of cost.
6. By informing the general public about the importance of forests.
We should also take the cooperation of our friends and neighbors for this work.
I hope the above information will be useful and important.
(आशा है, उपरोक्त जानकारी उपयोगी एवं महत्वपूर्ण होगी।)
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