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

  • question_answer
    Kunal took few iron turnings and mixed them well with sulphur powder. He could separate the iron turnings with the help of a magnet. He heated the mixture for some time and tried to separate the iron turnings with the magnet but he could not. Why?

    A)  On heating, a chemical change takes place and a new compound is formed.

    B)  On heating, iron becomes non-magnetic hence, it is not attracted by magnet.

    C)  On heating, a physical change takes place hence iron and sulphur gets mixed up.

    D)  On heating, iron evaporates and only sulphur is left behind.

    Correct Answer: A

    Solution :

    \[\underset{Iron}{\mathop{Fe}}\,+\underset{Sulphur}{\mathop{S}}\,\xrightarrow{Heat}\underset{Iron\,\,sulphide}{\mathop{FeS}}\,\] On heating iron and sulphur, a new substance, iron sulphide is formed, so it is a chemical change.


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