8th Standard New Syllabus Chapter Five Important Question

8th Standard EM

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Science

Use Blue Pink
Time : 04:00:00 Hrs
Total Marks : 100

    Part-A 

    Multiple Choice Question

    6 x 1 = 6
  1. Burning of paper is a______ change.

    (a)

    Physical

    (b)

    chemical

    (c)

    physical & chemical

    (d)

    neutral

  2. The burning of matchstick is an example for chemical reaction based on______

    (a)

    Contact

    (b)

    electricity

    (c)

    light

    (d)

    catalyst

  3. ______ metal undergoes rusting.

    (a)

    tin

    (b)

    sodium

    (c)

    copper

    (d)

    iron

  4. The pigment responsible for browning of apples is______.

    (a)

    Hydrated iron (II) oxide

    (b)

    melanin

    (c)

    starch

    (d)

    ozone

  5. Which of the following factor induces electrolysis?

    (a)

    Heat

    (b)

    light

    (c)

    electricity

    (d)

    catalysis

  6. Dissolved gases like sulphur dioxide, nitrogen oxides in rain water causes______

    (a)

    Acid rain

    (b)

    base rain

    (c)

    heavy rain

    (d)

    neutral rain

  7. Part-B

    Fill In The Blanks
    4 x 1 = 4
  8. ______ is the basic material to manufacture urea.

    ()

    Ammonia

  9. Electrolysis of Brine solution gives ______ gases.

    ()

    Chlorine and hydrogen

  10. ______ is a chemical substance which alters the speed of a chemical reaction.

    ()

    catalyst

  11. ______ is the enzyme responsible for browning of vegetables, fruits.

    ()

    Polyphenol oxidase or tyrosinase.

  12. Part-A 

    Match The Following Question
    6 x 1 = 6
  13. Electrolysis

  14. (1)

    Decomposition

  15. Thermolysis

  16. (2)

    Brine

  17. food

  18. (3)

    Oxygen

  19. Rancidity

  20. (4)

    Decomposition of limestone

  21. Ozone

  22. (5)

    Fish

  23. Calcium Oxide

  24. (6)

    Photosynthesis

    Part-C

    Answer The Following Question
    6 x 2 = 12
  25. Define catalysis

  26. What happens when an iron nail is placed in copper sulphate solution?

  27. What is pollution?

  28. Why photosynthesis is a chemical reaction?

  29. Kumar is going to build a house. To purchase the iron rods required for construction, he visited an Iron& steel shop nearby. The seller showed him some Iron rods which are fresh and good. He also showed him little older Iron rods which are brownish in appearance. The price of fresh rods are costlier than the older ones, the seller also gave some offer to older ones. Kumar’s friend Ramesh advised him not to buy the cheaper rods.
    a) Is Ramesh right in his suggestion?
    b) Could you explain the reason for his suggestion?
    c) What are the values shown by Ramesh?

  30. Palanikumar is a Lawyer. He lives in a costly flat. Due to high rent, he wants to shift his residence to a place where he has a chemical industry nearby. There the rent is very cheap and the area is less populated also. Rajasekar, his son studying VIII does not like this and likes to go to some other place.
    a) Is Rajasekar right in his attitude?
    b) Why did he refuse to go there?
    c) What are the values shown by Rajasekar?

  31. Part-D

    Answer The Following Question

    2 x 3 = 6
  32. Explain the role of yeast in making cakes?

  33. Justify the statement. Burning of fossil fuels is responsible for global warming.

  34. Part-F

    Answer The Following Question

    3 x 5 = 15
  35. Explain how food items are spoilt due to chemical reactions?

  36. Explain the three types of pollution.

  37. Explain any three conditions that is required for a chemical reaction to take place by citing one example each.

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