9th Class Science Is Matter Around Us Pure Question Bank MCQs - Is Matter Around us Pure

  • question_answer
    Which of the following are chemical changes? (NCERT Exemplar)
    I. Decaying of wood
    II. Burning of wood
    III. Sawing of wood
    IV. Hammering of a nail into a piece of wood

    A) I and II

    B) II and III

    C) III and IV

    D) I and IV

    Correct Answer: A

    Solution :

    [a]
    Options (I) Decaying of wood and (II)
    Burning of wood are chemical changes, because in these processes, the chemical composition of wood is changed and new substances are formed, which cannot be converted back into their original form.
    In (III) Sawing of wood and (IV)
    Hammering of a nail into a piece of wood, chemical composition of wood is not changed, therefore, (III) and (IV) are physical changes.


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