Changes around Us - Solutions
CBSE Class–VI Subject Science
NCERT Solutions
(CHAPTER-06)
CHANGES AROUND US
Question 1. Walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Answer: Yes, this can be reversed by unfolding the folded clothes.
Question 2. You accidently dropped your favorite toy and broke it. This is a change you did not want. Can this change be reversed?
Answer: No, this change cannot be reversed.Breaking a toy is an irreversible change.
Question 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. 2. 3. 4. 5. 6. | The sawing of a piece of wood. The melting of ice candy Dissolving sugar in water The cooking of food The ripening of mango Souring of milk |
|
Answer:
S No. | Change | Can be reversed Yes/No |
1. 2. 3. 4. 5. 6. | The sawing of a piece of wood. The melting of ice candy Dissolving sugar in water The cooking of food The ripening of mango Souring of milk | No Yes Yes No No No |
Question 4. A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer: We can reverse this change if the picture is made by pencil on drawing sheet. We can't reverse this change if the picture is made by pen, oil colour or sketch pen.
Question 5. Give example to explain the difference between changes that can or cannot be reversed.
Answer: (i) Paper can be folded to make different shapes. This is reversible change as shapes of paper can be unfolded back into paper sheet. But when paper is burnt and turned into ash, it can't be reversed.
(ii) If we fill balloon with air, the shape and size of the balloon changes. This change can be reversed but if balloon burst while inflating then this change can't be reversed.
(iii) The shape of rubber band can be changed by stretching which can be reversed
Question 6. A thick coating of paste of Plaster of Paris is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilized. Can the change in POP be reversed?
Answer: No, the change in plaster of Paris cannot be reversed as it became hard on drying and new product is formed.
Question 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?
Answer: No, because this is an irreversible chemical change.
