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SAI International School
                                               Subject - Chemistry
                                                     Class - VIII
                                        Topic – Combustion and Flame
                  Sub-Topic- Types of combustion, Calorific Value and Numericalṣ
                                                        Flame


                                              Practice Worksheet -1






           Q. No.                                Questions                                 Skill    Marks
               1.    Which one of the following is a combustible substance?                U        1
                                a.  Iron nail.
                                b.  Glass.
                                c.  Stone piece.
                                d.  Wood.
               2.    The substance expected to have the highest ignition                   U        1
                      temperature out of the following is
                                a.  Kerosene.
                                b.  Petrol.
                                c.  Coal.
                                d.  Alcohol.
              3.      The calorific value of a fuel is expressed in a unit called          .        1
                                 a.  Kilojoule per litre.
                                 b.  Kilogram per mililitre.
                                 c.  Kilojoule per gram.
                                 d.  Kilojoule per kilogram.
              4.      Choose the correct option from the following:                        U + A    1
                      (a) If both Assertion and Reason are correct and Reason is the
                      correct explanation of Assertion.
                      (b) If both Assertion and Reason are correct, but Reason is not
                      the correct explanation of Assertion.
                      (c) If Assertion is correct but Reason is incorrect.
                      (d) If Assertion is incorrect but Reason is correct.
                      (e) If Assertion & Reason both are incorrect.
                      Assertion (A): Kerosene oil does not catch fire on its own at
                      room temperature.
                      Reason (R): A combustible material cannot catch fire as long
                      as its temperature is lower than its ignition temperature.
              5.      Assertion (A): Phosphorus burns in air at room temperature.          U + A    1
                      Reason (R): It is an example of spontaneous combustion.
              6.      How carbon dioxide can control fire?                                 U        1
              7.      It is difficult to burn a heap of green leaves but dry leaves catch  U        1
                      fire easily. Explain.
              8.      Ram and Shyam were studying about combustion and flame.              R + A    3
                      The teacher asked them, what would be the conditions
                      necessary for combustion to take place? Help Ram and Shyam
                      in getting the answer.
              9.        i.   Which zone of a flame does a goldsmith use for melting        U + R    2 + 1 =
                             gold and silver and why?                                               3

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