NCERT Solutions for Class 6 Science Chapter 6 Changes around Us
NCERT solutions for class 6 science chapter 6 changes around us-Exercises
Question: 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 change can be reversed.
Question: 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, this change cannot be reversed.
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. |
The sawing of a piece of wood. |
|
|
2. |
The melting of ice candy. |
|
|
3. |
Dissolving sugar in water. |
|
|
4. |
The cooking of food. |
|
|
5. |
The ripening of a mango. |
|
|
6. |
Souring of milk. |
Answer:
|
S. No. |
Change |
Can be reversed (Yes/No) |
|
1. |
The sawing of 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. |
Question: 4 A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer: The answer depends on using what kind of material the drawing has been made. If it has been made using a pencil then the drawing might be erasable and the change can be reversed but if the drawing has been made using a pen or marker then the drawing is permanent and it cannot be erased and hence the change cannot be reversed.
Question: 5 Give examples to explain the difference between changes that can or cannot be reversed.
Answer: The following examples explain the differences between changes that can or cannot be reversed.
(a). A ball of clay shaped into a pot can be brought back to its original shape and therefore the change can be reversed. However, if it is baked the pot thus formed cannot be changed back to soft clay and therefore the change cannot be reversed.
(b). Pieces of raw vegetables mixed together can be separated and therefore the change(the mixing) can be reversed but if we cook the vegetables they cannot be brought back to the raw state and therefore the change cannot be reversed.
Question: 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: On mixing POP with water the POP reacts with water to give a different substance and this change cannot be reversed.
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: Once cement mixes with water they both react together and the substance formed hardens and this change cannot be reversed.
Study Resources Quick Links
Study Notes
Reference Books Solutions
- HC Verma Part 1
- HC Verma Part 2
- RD Sharma Class 9
- RD Sharma Class 10
- RS Aggarwal Class 10
- Lakhmir Singh Class 9
- Lakhmir Singh Class 10
