CBSE Class VIII (8th) Science | All Chapters Solved Exercises

Chapter 1. CROP PRODUCTIION AND MANAGEMENT | CBSE Class VIII (8th) Science | Solved Exercises

Chapter 2. MICROORGANISMS : FRIEND AND FOE | CBSE Class VIII (8th) Science | Solved Exercises

Chapter 17. STARS AND THE SOLAR SYSTEM | Science | CBSE Class VIII (8th) | Solved Exercises

Things to remember....

1. The phases of the moon occur because we can see only that part of the moon which reflects the light of the Sun towards us.
2. Stars are celestial bodies that emit light of their own. Our sun is also a star.
3. It is convenient to express distances of stars in light years.

Chapter 16. LIGHT | Science | CBSE Class VIII (8th) | Solved Exercises

Question 1. Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.

Answer : We can not see objects in the dark room without the presence of light or a lighted object it self . We may see an object only when, the light from an object enters our eyes.

Chapter 15. SOME NATURAL PHENOMENA |Science | CBSE Class VIII (8th) | Solved Exercises

Select the correct option in Questions 1 and 2.
Question 1. Which of the following cannot be charged easily by friction?

1. (a) A plastic scale
2. (b) A copper rod
3. (c) An inflated balloon
4. (d) A woolen cloth.

Answer : (b) A copper rod

Chapter 14. CHEMICAL EFFECTS OF ELECTRIC CURRENT | Science | CBSE Class VIII (8th) | Solved Exercises

Things to remember....

1. Some liquids are good conductors of electricity and some are poor conductors.
2. Most liquids that conduct electricity are solutions of acids, bases and salts.
3. The passage of an electric current through a conducting liquid causes chemical reactions.
4. The resulting effects are called chemical effects of currents.
5. The process of depositing a layer of any desired metal on another material, by means of electricity, is called electroplating.

Chapter 13. SOUND |Science | CBSE Class VIII (8th) | Solved Exercises

Things to remember....

1. Sound is produced by vibrating objects.
2. In human beings, the vibration of the vocal cords produces sound.
3. Sound travels through a medium (gas, liquid or solid). It cannot travel in vacuum.
4. It sends the signals to the brain. This process is called hearing.
5. The number of oscillations or vibrations per second is called the frequency of oscillation.

Chapter 12. FRICTION |Science | CBSE Class VIII (8th) | Solved Exercises

Things to remember....

1. Friction opposes the relative motion between two surfaces in contact. It acts on both the surfaces.
2. Friction depends on the nature of surfaces in contact.
3. For a given pair of surfaces friction depends upon the state of smoothness of those surfaces.

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Chapter 11. Force And Pressure | Science | CBSE Class VIII (8th) | Solved Exercises

Question1. : Give two examples each of situations in which you push or pull to change the state of motion of objects.
Answer :

1. Opening or shutting a door
2. A cricket ball hit by a batsman  

Chapter 10. Reaching The Age Of Adolescence | Science | CBSE Class VIII (8th) | Solved Exercises

Question 1. What is the term used for secretions of endocrine glands responsible for changes taking place in the body?

Answer :The secretions of endocrine glands responsible for changes taking place in the body is called hormones.Hormones are chemical substances, which are released by endocrine glands directly into the blood stream.. The changes which occur at onset of puberty and adolescence are controlled by hormones

Chapter 9. REPRODUCTIION IN ANIMALS | Solved Exercises | CBSE Class VIII (8th) Science

• Question 1. Explain the importance of reproduction in organisms.
• Answer : The process of reproduction in organisms is essential for the continuation of theirs respective species. The reproduction in organisms is very important as it ensures the continuation of similar kinds of individuals, generation after generation.In larger context, reproduction in various species of animals and plants kingdom, forms part of ecosystem and which helps in maintaining it, by evolution chain. 
•  

CBSE Class VIII (8th) Science | Chapter 8. CELL — STRUCTURE AND FUNCTIONS | Solved Lesson Exercises

Question 1. Indicate whether the following statements are True (T) or False (F).

1. Unicellular organisms have one-celled body. (T/F)
2. Muscle cells are branched. (T/F)
3. The basic living unit of an organism is an organ. (T/F)
4. Amoeba has irregular shape. (T/F)

CBSE Class VIII (8th) Science | Chapter 7. CONSERVATION OF PLANTS AND ANIMALS | Lesson Exercises

Question 1. Fill in the blanks:

(a) A place where animals are protected in their natural habitat is called  wildlife sanctuaries .

(b) Species found only in a particular area is known as Endemic species .

(c) Migratory birds fly to far away places because of  climatic changes.

Question 2. Differentiate between the following:

(a) Wildlife sanctuary and biosphere reserve

(b) Zoo and wildlife sanctuary

(c) Endangered and extinct species

(d) Flora and fauna

CBSE Class VIII (8th) Science | Chapter 6. COMBUSTION AND FLAME| Lesson Exercises

Question 1. List conditions under which combustion can take place.

Answer :  Conditions under which combustion take places :

1. Some Fuel is  is required for combustion. During combustion a fuel substance reacts with oxygen to give off heat.The fuel may be solid, liquid or gas.
2. Oxygen in air  is essential for combustion. Combustion can not take place in the absence of air (oxygen).
3. For a combustion,  an inflamabe substance must be heated to its ignition tempreture. Ignition temperature is the lowest temperature at which a combustible substance catches fire.

CBSE Class VIII (8th) Science | Chapter 5. COAL AND PETROLEUM | Lesson Exercises

Question 1. What are the advantages of using CNG and LPG as fuels?

Answer : CNG -  compressed natural gas, is stored under high pressure as compressed natural gas (CNG).  CNG is a very important fossil fuel because it is easy to transport through pipes. CNG is used for power generation. It is now being used as a fuel for transport vehicles because it is less polluting. It is a cleaner fuel. Similarly, LPG- Liquified Petroleum Gas is used as fuel for home and industry as it is less polluting and easy to transport and to use.

Question 2. Name the petroleum product used for surfacing of roads.

Answer : Earlier coal-tar a black, thick liquid which is obtained from coal processing, and is   a mixture of about 200 substances was mainly used for metalling or surfacing of the roads, now a days, bitumen, which is a petroleum product, is used in place of coal-tar for metalling or surfacing of the roads.

CBSE Class VIII (8th) - Science | Chapter 4. MATERIALS : METALS AND NON-METALS | Lesson Exercises

Question 1. Which of the following can be beaten into thin sheets?

(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen

Answer : (a) Zinc

Question 2. Which of the following statements is correct?

(a) All metals are ductile.

(b) All non-metals are ductile.

(c) Generally, metals are ductile.

(d) Some non-metals are ductile.

Answer : (c) Generally, metals are ductile.

CBSE Class VIII (8th) - Science Chapter 3. SYNTHETIC FIBRES AND PLASTICS | Lesson Exercises

CBSE Class VIII (8th) - Science Chapter 3. SYNTHETIC FIBRES AND PLASTICS

Question 1. Explain why some fibres are called synthetic.

Answer : While natural fibres are obtained from plants and animals, synthetic fibres on the other hand, are  obtained by human beings from the chemical processing of petrochemicals. Petrochemicals when processed, results in different type of synthesised products like Petrol, Kerosene, Grease, Bitumen and polymers. Synthetic fibres are made from Synthetic polymers.  That is why these are called synthetic or man-made fibres.

CBSE Class VIII (8th) - Science Chapter 2. MICROORGANISMS : FRIEND AND FOE | Lesson Exercises

1.Question:  Fill in the blanks:

(a) Microorganisms can be seen with the help of a  microscope.

(b) Blue green algae fix  nitrogen directly from air to enhance fertility of soil.

(c) Alcohol is produced with the help of  yeast.

(d) Cholera is caused by  pathogens.

2.Question: Tick the correct answer:

(a) Yeast is used in the production of 

(i) sugar (ii) alcohol (iii) hydrochloric acid (iv) oxygen

Answer: (ii) alcohol

CBSE Class VIII (8th) Science | Chapter 1. CROP PRODUCTION AND MANAGEMENT | Lesson Exercises

1. Question :  Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation
Solution: 
(a) The same kind of plants grown and cultivated on a large scale at a place is called crop.
(b) The first step before growing crops is Preparation of the soil.
(c) Damaged seeds would  float on top of water.
(d) For growing a crop, sufficient sunlight and nutrients and water from the soil are essential.