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

  • question_answer
    DIRECTIONS: Read the passage given below and answer the questions that follow. Passage - 1 A change in which two or more substances (reactants) combine to produce one or more new substances (products) that has/have different chemical properties than the reactants is called chemical change. In a chemical change new products are formed. The characteristics of a chemical change are following: 1. Heat, light or any other radiation (ultraviolet) may be given off or absorbed. 2. Sound may be produced. 3. A change in smell may take place or a new smell may be given off. 4. A colour change may take place. 5. A gas may be formed. Change in which only physical properties of any substances get changed and no new substance is formed is called a physical change. Such as shape, size, colour and state, is known as physical change. A physical change is mostly reversible and during physical change no new substances are formed. Which of the following is a chemical change?

    A) Foul smell comes when food gets spoiled

    B) Pollution of air due to explosion of fire-work.

    C) Change in colour of a cut apple if left outside.

    D) All of the above.

    Correct Answer: D

    Solution :

    Change of smell, formation of new products and change of colour all are signs of a chemical change.


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