Changes Around Us Model Question Paper

7th Standard EM

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Science

Time : 01:30:00 Hrs
Total Marks : 50
    3 x 1 = 3
  1. When a woolen yarn is knitted to get a sweater, the change can be classified as _______ .

    (a)

    physical change

    (b)

    chemical change

    (c)

    endothermic change

    (d)

    exothermic change

  2. ________is an example of a periodic change.

    (a)

    Earthquake.

    (b)

    Formation of rainbow in sky

    (c)

    Occurrence of tides in seas.

    (d)

    Showering of rain

  3. _________ is not a chemical change.

    (a)

    Dissolution of ammonia in water

    (b)

    Dissolution of carbon-di-oxide in water

    (c)

    Dissolution of oxygen in water

    (d)

    Melting of polar ice caps

  4. 3 x 1 = 3
  5. Filling up a balloon with hot air is a _____ change.

    ()

                   

  6. Opening a gas cylinder knob converts _____ fuel into ________ fuel. This is an example of _____ change.

    ()

                

  7. Respiration is a _____________ change.

    ()

                      

  8. 4 x 1 = 4
  9. Cutting of cloth is an example of a periodic change.

    (a) True
    (b) False
  10. Taking a glass of water and freezing it by placing it in the freezer is a chemical change.

    (a) True
    (b) False
  11. A bean plant collecting sunlight and turning it into bean seeds is an example of physical and non-periodic change.

    (a) True
    (b) False
  12. Tarnishing of silver is an example of endothermic change.

    (a) True
    (b) False
  13. 2 x 2 = 4
  14. Assertion: The process of conversion of liquid water to its vapours by heating the liquid is called boiling.
    Reason: The process of conversion of water vapours to liquid by cooling the vapours is called condensation.
    a. Both A and R are true and R is the correct explanation of A.
    b. Both A and R are true but R is not the correct explanation of A.
    c. A is true but R is false.
    d. A is false but R is true.

  15. Assertion: Burning of wood log to charcoal is a physical change.
    Reason: The products formed of burning a piece of wood can be easily converted back to wood log.
    a. Both A and R are true and R is the correct explanation of A.
    b. Both A and R are true but R is not the correct explanation of A.
    c. A is true but R is false.
    d. A is false but R is true.

  16. 2 x 2 = 4
  17. Physical Change: Boiling::Chemical Change: ________.

  18. Wood to saw dust:_________ :: Wood to Ash: Chemical change

  19. 4 x 2 = 8
  20. State two examples of periodic changes.

  21. Cold milk is heated and it becomes hot. Which type of change it is?

  22. What type of change is colouring of a paper?

  23. What type of energy changes is associated when ice melts?

  24. 3 x 3 = 9
  25. Distinguish physical and chemical changes.

  26. How can a change occur in a substance?

  27. What is the difference between dissolution of sugar and burning of sugar?

  28. 3 x 5 = 15
  29. Explain the following statement: Digestion is a chemical change.

  30. How the iron blade is fixed into a wooden handle in tools used to dig the soil?

  31. Boiling of water is a physical change; but boiling of egg is a chemical change. Why?

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