Ques 1: To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Ans 1: Yes, by unfolding the dress this change can be reversed.
Ques 2: You accidentally dropped your favorite toy and broke it. This is a change you did not want. Can this change be reversed?
Ans 2: No, it cannot be reversed, so it is an irreversible change.
Ques 3: Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
S. No. | Change | Can be reversed (Yes/ No) |
1. | The sawing a piece of wood |
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2. | The melting of ice candy |
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3. | Dissolving sugar in water |
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4. | The cooking of food |
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5. | The ripening of a mango |
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6. | Souring of milk |
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Ans 3:
S. No. | Change | Can be reversed (Yes/ No) |
1. | The sawing a piece of wood | No |
2. | The melting of ice candy | Yes |
3. | Dissolving sugar in water | Yes |
4, | The cooking of food | No |
5. | The ripening of a mango | No |
6. | Souring of milk | No |
Ques 4: A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Ans 4: It all depends on situations:
Ques 5: Give examples to explain the difference between changes that can or cannot be reversed.
Ans 5: Examples of Reversible Changes:
Ques 6: A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
Ans 6: When water is added to POP, it undergoes a chemical change. Its composition changes and is converted into another substance. Since it is a chemical change, so it cannot be reversed.
Ques 7: A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
Ans 7: Due to water, the cement hardens and its composition changes. Since it is a chemical change which cannot be reversed.
85 videos|305 docs|208 tests
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1. What are the different types of changes around us? |
2. What is the difference between physical and chemical changes? |
3. How can we observe physical changes in everyday life? |
4. How can we differentiate between physical and chemical changes? |
5. What are the examples of biological changes? |
85 videos|305 docs|208 tests
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