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7th Class Science Physical and Chemical Changes Question Bank Physical and Chemical Changes

  • question_answer
    In a pressure-kerosene stove,          
    (i) We pump kerosene and convert it into vapours.                         
    (ii) The vapours are then ignited.      
    Which of the following is true about the above statements?                    

    A)  (i) is a chemical change; (ii) is a physical change,                 

    B)  (i) is a physical change; (ii) is a chemical change.                 

    C)  Both (i) and (ii) are physical changes.

    D)  Both (i) and (ii) are chemical changes.

    Correct Answer: B

    Solution :

    Pumping kerosene and conversion to its vapours involve change in the state only (from liquid to vapours) and no new substance is formed. So, it is a physical change. During ignition of vapours, a lot of heat is given out and new substances are formed. Therefore, it is a chemical change.


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