1. Setting of curd is a chemical change since a new substance (lactic acid) is formed which differs in taste from the original substance (fats and proteins) i.e. milk. Also the change is irreversible (curd cannot be converted into milk). https://www.tiwariacademy.com/ncert-solutions/class-7/science/chaRead more

    Setting of curd is a chemical change since a new substance (lactic acid) is formed which differs in taste from the original substance (fats and proteins) i.e. milk. Also the change is irreversible (curd cannot be converted into milk).

    https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

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  2. Physical Changes: On heating, candle wax gets melted is a physical change. Since it again turns into solid wax on cooling. Chemical Changes: The wax near to flame burns and gives new substances like Carbon Dioxide, Carbon soot, water vapour, heat and light. Cooking of food, is another example whereRead more

    Physical Changes: On heating, candle wax gets melted is a physical change. Since it again turns into solid wax on cooling.
    Chemical Changes: The wax near to flame burns and gives new substances like Carbon Dioxide, Carbon soot, water vapour, heat and light.
    Cooking of food, is another example where both physical and chemical changes occurs.

    https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

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  3. This a chemical change as new products are formed. Baking soda + Lemon juice ------------> Salt + Carbon dioxide + Water When acid react with carbonates, salt is formed releasing carbon dioxide and water. https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

    This a chemical change as new products are formed.
    Baking soda + Lemon juice ————> Salt + Carbon dioxide + Water
    When acid react with carbonates, salt is formed releasing carbon dioxide and water.

    https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

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  4. Changes in which new substances are formed are called chemical changes. https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

    Changes in which new substances are formed are called chemical changes.

    https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

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  5. Changes in which only physical properties of a substance change are called physical changes. https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

    Changes in which only physical properties of a substance change are called physical changes.

    https://www.tiwariacademy.com/ncert-solutions/class-7/science/chapter-6/

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