Very Short Answer Type Questions
1. Name three useful products of coal.
2. Which product of coal is used as a reducing agent in the extraction of metals?
3. Name the process by which plant material (or vegetation) buried deep under the earth was slowly converted into coal.
4. Name the product of coal, which is a thick black liquid with an unpleasant smell.
Various steps involved in agriculture are collectively known as agricultural practices, which include:
Here is a worksheet (Fill in the blanks) as PDF.
Download worksheet
👉See Also:
Ch4 - Metals & Non-Metals(Q & A)
Ch4 - Metals and Non-Metals (MCQs)
Ch4 - Metals and Non-Metals (Prachi Textbook Solutions)
Ch4 - Uses of Some Common Metals and Non-Metals
Ch4 - Metals and Non-Metals (MCQs) (2021-22)
FORCE
Q1. Which physical quantity is required to change the state of motion of a body?
Q2. Give an example in which force is required to slow down the speed of a fast-moving object.
Q3. Define force
FORCE - A PUSH OR A PULL
Q4. In lifting an object, do we require any force? Explain using an example.
Q5. Give an example of a force acting on an object.
Q6. Mention any two effects of force.
FORCES ARE DUE TO AN INTERACTION
Q7. Give two examples in which push is required to move a body.
Q8. What is the minimum number of objects that must interact for a force to come into play?
Q9. When we pull a dog by some force, does the force of our also acts on us?
EXPLORING FORCES
Q10. What will happen to a block if it is pushed by two equal and opposite forces?
Q11. Why has it become easier to push a bench by two or more students in the same direction rather than pushing alone?
Q12. What do you mean by net force?
FORCE CAN CHANGE THE STATE OF MOTION
Q13. What happens if the net force acting on an object is non-zero?
Q14. Can the application of force increase the speed of a moving object? Explain using an example.
Q15. What happens if the force is applied in the direction of the moving object?
Q16. In what direction will you apply a force to stop a moving body?
Q17. What do you mean by state of motion?
Q18. Give an example of the state of zero speed.
Q19. Does the application of force always result in a change in the state of motion? Explain with an example.
FORCE CAN CHANGE THE SHAPE OF AN OBJECT
Q20. What happens when we apply force to a rubber ball by pressing it between our palms?
Q21. Give two examples in which force is required to change the shape of an object.
CONTACT FORCES
Q22. What kind of force is responsible for lifting a bucket full of water?
Q23. What do you mean by muscular force?
Q24. Give two examples in which animals make use of muscular force to carry out their physical activities
Q25. Give two examples in which we make use of muscular force to carry out physical activities?
Q26. Define contact forces.
Q27. Mention any two types of contact forces.
Q28. Define friction.
Q29. Give two examples where friction acts on an object.
Q30. What is the direction of frictional force?
Q31. Give an example to show that frictional force is a contact force.
Q32. Does fluid oppose the motion of an object moving in it? Explain using a suitable example.
Q33. Why does a ball stop by itself when rolled on the floor?
NON-CONTACT FORCES
Q34. Define non-contact forces.
Q35. Mention any two examples of non-contact force.
Q36. How can you say that the magnetic force is a non-contact force?
Q37. What do you mean by magnetic force?
Q38. What happens when two magnetic poles are brought closer to each other?
Q39. State whether the force exerted by a magnet on a piece of iron is a contact or a non-contact force. Explain your answer.
Q40. What do you mean by an electrostatic force?
Q41. How can you say that an electrostatic force is a non-contact force?
Q42. What happens when a straw is rubbed with a sheet of paper?
Q43. Is electrostatic force always repulsive? Explain your answer.
Q44. What do you mean by gravitational force?
Q45. How can you say that the gravitational force is a non-contact force?
Q46. When an object is dropped from a certain height it comes towards the earth's surface. Which force is responsible for the same?
Q47. Can only earth produce the gravitational force?
Q48. Can gravitational force be repulsive?
Q49. Give two examples where the movement of an object is due to the gravitational force.
Q50. Up to how much distance above the earth's surface can we experience gravitational force?
Q51. Does gravitational force exist between tiny particles?
Q52. Earth attracts the falling apple from trees, does the apple also attract the earth?
Q53. What do you mean by gravity?
Q54. Gravitational force can be exerted between what type of objects?
PRESSURE
Q55. Define pressure.
Q56. What is the relation between force and pressure?
Q57. How does pressure vary with the area of contact?
Q58. Why is it easier to cut vegetables with a sharp knife?
Q59. Why the railway tracks are placed on broad wooden or concrete wedges?
Q60. Why are sharp nails easier to push into the wall?
Q61. "Shoulder bags are made with are made with broad straps". Give reason.
Q62. Why do the porters place a round piece of cloth on their heads?
Q63. Why is it easier for the camel to walk in the desert?
Q64. How can we increase the pressure?
Q65. At what angle the force must act on the surface to get maximum pressure?
PRESSURE EXERTED BY LIQUIDS AND GASES
Q66. Explain using a suitable example, the pressure of paper? increases with depth in liquids.
Q67. What are fluids?
Q68. Show that the pressure is exerted by the liquids on the walls of the container.
Q69. Do gases exert pressure?
Q70. Why does the water from a leaking pipe come like a fountain?
Q71. Is it possible to inflate a balloon with a hole in it? Explain your answer.
ATMOSPHERIC PRESSURE
Q72. What is the atmosphere?
Q73. Up to what height does the atmosphere extend above the surface?
Q74. What do you mean by atmospheric pressure?
Q75. On what factors does the atmospheric pressure depend?
Q76. Does atmospheric pressure depend on the surface area?
Q77. Why does a rubber sucker stick to the flat surface?
Q78. Why don't we get crushed due to atmospheric pressure?
Q79. Why do astronauts wear special suits in space?
Q80. Deep-sea divers use some special suits while diving. Give reason.
Q81. What happens to the atmospheric pressure as we move to higher altitudes above the earth's surface?
Q82. Is there any role of gravity in atmospheric pressure? Explain your answer.
Q83. Discuss an activity which shows that atmospheric pressure is huge in magnitude.
👉See Also:
Ch 11 - Force and Pressure (Q & A)
Ch11 - Force and Pressure (MCQs)
Ch 11 - Force (What is Inertia?)
Ch 11 - Force and Pressure (Assignment Sheet)
Ch 11 - Force and Pressure (Worksheet)
Force, Pressure and Pressure (Q & A-II)
Force, Pressure and Friction (Short Q & A)
Force, Pressure and Friction (MCQs)
Friction is a necessary evil. It is a type of contact force which always opposes the motion of one object over the other object in contact.
Here worksheet (PDF) is available to test your basic understanding about the chapter.
👉Download the friction worksheet.
Q1. State the effects of force.
Answer: Force may:
➀ make an object move from rest.
➁ change the speed of a moving object.
➂ change the direction of motion of an object.
➃ change the shape of an object.
➄ stop a moving object
Q2. Calculate the pressure exerted by a force of 100 N on an area of 4 m²
Fill in the blanks with suitable words.
1. ________ gas in air is essential for combustion.
2. A chemical process in which a substance reacts with oxygen to give off heat is called __________.
3. During the process of combustion, _______ and light are given out.
Q1: In general, oxides of non metals are ________ in nature?
(a) basic
(b) acidic
(c) neutral
(d) amphoteric
Q2: The percentage of which of the following components of air always varies from one place to the other?
(a) O₂
(b) N₂
(c) Water vapour
(d) CO₂
Fill in the blanks with suitable words.
1. The period of life, when the body undergoes certain noticeable changes, leading to reproductive maturity is called __________.
2 _______ is the start of the time when a boy is biologically ready to become a father and a girl is ready to become a mother.
3. ______ are thread-like structures in the nucleus carrying genetic information.
Q1: All metals are solids except:
(a) Sodium
(b) Calcium
(c) Mercury
(d) Copper
Q2: Which of the following metal does not react with dilute Hydrochloric acid?
(a) Iron
(b) Sodium
(c) Magnesium
(d) Copper
Fill in the blanks with suitable words:
1. The stars, the planets, the moon and many other objects in the sky are called _________ objects.
2. The various shapes of the bright part of the moon as seen during a month are called ________ of the moon.
3. The moon is visible due to reflected ________.
Fill in the blanks with suitable words.
1. _________ are the substances obtained from petroleum and natural gas.
2. Petroleum is obtained from dead remains of living organisms, that is why it is called a ________ fuel.
3. Kerosene is used in ______ aircrafts.
4. In India, ________ gas has been found in Tripura, Rajasthan, Maharashtra and in the Krishna Godavari delta.
Fill in the blanks with suitable words:
1. Cultivation of plants and rearing of animals for food and other beneficial items is called ____________.
2. When plants of the same kind are grown and cultivated at one place on a large scale, it is called a ________.
3. The process of loosening and turning of the soil is called _________ or _________.
Q1: What is a plastic?
Answer: Plastic is also a polymer like the synthetic fibre. All plastics do not have the same arrangement of units. In some, it is linear, whereas in others it is cross-linked.
Q2: What are the main properties of plastics?
Answer:
① Plastic is easily mouldable in all types of possible shapes.
② Most plastics are light, chemically stable and do not rust. The weight of plastic is less when compared to that of metal.
③ Some types of plastics are good insulaters and have low thermal conductivity.
④ Plastic can be recycled, coloured, reused, rolled into sheets or made into wires.
⑤ Most plastics have poor heat resistance.
⑥ Plastics have good durability (lasts longer).
CBSE Class 8 - Science - Conservation of Plants and Animals (Worksheet)
Directions: Fill in the blanks with suitable words:
1. Plants and animals of a particular area are known as the _________ and __________ of that area.
2. Red Data Book contains a record of __________ species.
3. _________ is the restocking of destroyed forests by planting new trees.
