CBSE Class 6 Science
Chapter 6: Changes around Us
NCERT Solutions
1. To 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 it
2. You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?
Answer: No. It cannot be reversed.
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.
Answer:
1. No
2. Yes
3. Yes
4. No
5. No
6. No
4. A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer: It can be reversible if it is drawn with a pencil.
5. Give examples to explain the difference between changes that can or cannot be reversed.
Answer: Melting of ice into water is an example for reversible change, because we can get the ice by the freezing the water again. Where are burning of a paper into ash is an irreversible change because we cannot get the paper back from ashes received.
Similarly, folding of a paper into a boat is a reversible change because we can get back the paper by unfolding it, whereas the cooking of food is an irreversible change because we cannot get the ingredients back from the cooked food
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?
Answer: We cannot get Plaster of Paris back in its original form. Hence it is an irreversible change
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. It is an irreversible change
