CBSE Class 8 Science Exam – Most Important Topics

Science is a wonderful subject only if one is able to grasp the concept. When it comes to preparing for the exam, although class 8 science is not a board exam, it still requires proper preparation because it helps students score more and prepares them for the future. However, the first step to preparing for a science exam is to understand the most important topics and to fully understand the syllabus. 

Chapters of Class 8 Science 

  •  Pollution of Air and Water
  •  Stars and the Solar System
  •  Light
  •  Some Natural Phenomena
  • Chemical Effects of Electric Current
  • Sound
  • Friction
  • Force and Pressure
  • Reaching the Age of Adolescence
  • Reproduction in Animals
  • Cell – Structure and Functions
  • Conservation of Plants and Animals
  • Combustion and Flame
  •  Coal and Petroleum
  • Materials: Metals and Non-Metals
  • Synthetic Fibres and Plastics
  •  Microorganisms: Friend and Foe
  •  Crop Production and Management

The chapters in CBSE class 8 science are 18. In science, it is not good to skip or neglect any one chapter. Therefore, it is important to be prepared and comprehend all the chapters thoroughly. 

Some Important Questions Chapter-wise 

Crop Production and Management

  1.   State the reason why Kharif crops are unable to be grown in the Rabi season?
  2.   What are the steps present in soil preparation?
  3.   In which medium do the plants grow? 
  4.   Should you dry grains before storing them? If yes, why?
  5.   How are manures prepared by the farmers?

Microorganisms: Friend and Foe

  1.   Explain more about microorganisms and microbes
  2.   Provide three examples of microorganisms.
  3.   Describe two multicellular Microorganisms.
  4.   What are the two types of Microorganisms and talk about their functions?
  5.   Who found the antibiotics? Name the inventor.

Synthetic Fibres and Plastics

  1. Can nylon fibres be used to make parachutes? Is it strong enough?
  2. State a few uses of PET
  3. What is melamine? Why is it used for making kitchenware?
  4. Why should we use polythene over natural materials?
  5. Why do we use plastic containers for food storage?

Materials: Metals and Non-Metals

  1.   What is the displacement reaction? Explain more with the help of an activity.
  2.   Explain the reaction of non-metals with oxygen. Give an example.
  3.   State five uses of metals and non-metals.
  4.   Write the difference between metals and non-metals based on their physical properties.
  5.   Write the two ductile metals.

 Coal and Petroleum

  1.   What are natural substances? Give two examples.
  2. Write a note on the purest form of carbon.
  3.   What is a coke and state its uses?
  4.   Give two fractions of petroleum?
  5.   What is called black gold and why?

Combustion and Flame

  1.   What is solid fuels? Give three examples.
  2.   Explain fuels on the basis of their states.
  3.   How does a fire extinguisher work? 
  4.   If you prepare tea in a paper cup, will it catch fire? If not, why?
  5.   What is the clean fuel used in buses? 

Conservation of Plants and Animals

  1. Explain about the major threat to the survival of organisms?
  2. What is biodiversity? Explain more. 
  3. Give us a few examples of two endemic flora
  4. Name a few plants that are found in the Satpura forest.
  5. What is a Red Data Book? Explain.

Cell – Structure and Functions

  1. Write a short note on plant cells and animal cells.
  2. What is a chloroplast? Explain.
  3. You must have come across the definition, cells are the basic structural and functional unit of life. Explain.
  4. Explain in detail about eukaryotes and prokaryotes?
  5. Explain the complete process of photosynthesis.

Reproduction in Animals

  1. Define reproduction. What are the modes of reproduction?
  2. What are the female reproductive organs?
  3. What is sperm and ovum? 
  4. Explain various modes of asexual reproduction.

 Reaching the Age of Adolescence

  1. When do noticeable changes begin in humans in adolescence?
  2. When it comes to growth, do girls and boys grow at the same rate?
  3. Name female hormone.
  4. What is menopause?
  5. What are chromosomes?

Force and Pressure

  1. How do you know if one object is moving faster than the other?
  2. When is the force applied?
  3. What happens when two forces move in an identical direction?
  4. A ball is at rest. You push it. So, why does it start moving?
  5. What is the role of force on speed in the context of moving objects?


  1.   Write some harms of friction.
  2.   What is sliding friction?
  3.   When you step on a banana peel, chances are you fall. Why?
  4.   In which direction frictional force acts on a moving object.
  5.   What is easier- rolling or sliding?


  1.   Do all bodies produce sound?
  2.   When the bell stops generating sound, touch it. Can you feel the vibration? What do you understand about this?
  3.   Name the sound-producing organ.
  4.   Can sound travel through a vacuum?
  5.   What is oscillatory motion?

Chemical Effects of Electric Current

  1.   What are insulators of electricity?
  2.   Name some substances other than water that conducts electricity?
  3.   Why does the bulb glow when switched on?
  4.   What is the magnetic effect of electric current?
  5.   What are electrodes?

 Some Natural Phenomena

  1. What are the three destructive natural events?
  2. Rubbing amber and fur causes which effect.
  3. Write the nature of the charges on a glass rod and silk cloth when they are rubbed with each other.
  4. What are the harmful effects of lightning if it occurs on a person.
  5. What is an earthquake?


  1.   Where does the image form in our eyes?
  2.   Which bird is called a night bird?
  3.   Which part of the eyes is controlled by the iris?
  4.   What is a kaleidoscope? What are its uses?
  5.   What is the function of rods and cones in our eyes?

 Stars and the Solar System

  1.   We see objects like stars and planets in the sky. What are they called?
  2.   Which day is New moon day? Why is it called so?
  3.   What is a light-year? Explain. 
  4.   What is the full form of IAU? Give a detailed explanation. 
  5.   Why does the sun rise east and set in the west?

Pollution of Air and Water

  1. Write about the percentage of nitrogen in the air? Explain its importance.
  2. What is acid rain and what gases are responsible for acid rain?
  3. Which events cause global warming? Explain.
  4. What is potable water? Explain in detail. 
  5. What are the elements present in the exhaust of automobiles?

Learning these important questions from the topics can help you before the exam. It is important for students to learn them thoroughly, without any mistakes. Remember, you must study all the chapters completely and solve the exercise questions and these important questions to prepare for the exam.