CBSE Class 8 EVS Revision Worksheet

Answer the following questions briefly

1. Why wide wooden sleepers are set below the railway tracks?

2. What are the major groups of microorganism?

3. Why sodium and potassium are stored in Kerosene?

4. Immersion rods of heating liquids are made up of metals. Give reason.

5. What is the weight of the air column in the area of 1cm2?

6. Why fossil fuels are exhaustible natural resources?

7. Where chromosomes are found? State their function.

8. The base of a dam is made broader than the rest of the wall. Why?

9. Why does energy consumption increases rapidly?

10. Why do lustrous metals lose their shine with time?

11. What is food poisoning?

12. What is the direction of force of friction?

13. Why do pressure cookers have plastic handles?

14. Why CNG is considered as a best fuel?

15. Why the friction between two surfaces increases when they are pressed harder?

16. Why do plants need a cell wall?

17. Why do boxers wear boxing gloves?

18. How bread comes out soft and fluffy after baking?

19. How is petroleum formed?

20. What are the characteristic of synthetic Fibre?

21. How is rayon different from other synthetic fibres?

22. Why potters place a round piece of cloth to carry heavy luggage?

23. How are you able to find the nature of metallic oxides?

24. How will you classify the bacterium penicillium –harmful or useful? Why?

25. One should not let water collect anywhere for a long time. Why

26. List the variety of coal in the order of increasing carbon content.

27. What is the role of microorganism in keeping the environment clean?

28 .A rocket has been fired upwards to launch a satellite in its orbit. What are the two forces acting on the rocket immediately after leaving the launching pad?

29. Give example to show friction as a friend and a foe?

30. How would the pressure change if:

a. Area is doubled keeping the force constant

b. Force is doubled keeping the area constant

31. Algae is considered to be closer to plants than to animal . Why?

II. Fill in the blanks with appropriate answers.

1. Sprinkling of powder on a carom board _________________friction.

2. Malaria is spread by _______________

3. The main source of plastic is _______________

4. A non - metal that occurs as solids at room temperature ____________

5. The ‘lead’ of the pencil is _________________

6. The alloy of copper, zinc and nickel is _________________

7. The control centre of the cell ________________

8. The Golgi body that helps in the transportation of substance within the cell _______________

9. A unicellular organism with no definite shape. ________________

10. The most abundant element in the universe ________________

11. Penicillin is made from a _____________

12. Raw materials used in the manufacture of Rayon ____________________

13. A thermoplastic used as a substitute for glass _________________

14. The extraction of pure metals from its ore ______________

15. The non-metal which has very high melting and boiling point __________________

16. Metals reacts with water vigorously with the evolution of _____________________gas.

17. Iron corrodes in the presence of _________________ and ________________

18. A metal that does not corrode in air ______________

19. A unicellular organism with no definite shape _____________

20. The powerhouse of the cell _________________

21. The organ for movement in paramecium ________________

22. The smallest cell in the human body __________________

23. The new cell formed by cell division is known as __________________

24. The frictional force that fluids exerts on a body is _________________

25. The kind of force a porter apply to lift an object _______________________

26. An instrument that measures the liquid pressure_____________________

27. The force that acts on an object at all times _______________________

28. Long chain of molecules containing thousands of similar small molecules called monomers _______________

29. Metals react with acids to produce _____________ gas.

30. The powerhouse of the cell is ___________________.