class 6 ch 7

Changes Around us : NCERT Class VI Science Lesson 6

NCERT Class VI
Science textbook:
Lesson6 :Changes Around us.


Exercise
  
1.Question.To walk through a waterlogged area,you usually shorten the length of your dress by folding it. can be reversed?
Answer. Yes. This change can be reversed.

2.Question. You accidentally dropped your favorite toy and broke it.Can this change reversed?
Answer.No. This change cannot be reversed.

3.Question. Some changed are listed in the following table.For each change, write in the blank column whether the change can be reversed or not?
Answer. 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

4.Question. A drawing sheet change when you draw a picture on it. Can you reverse this change?
Answer.If the picture is drawn a pencil, then it can be erased, hence change can be reversed.
But if picture is drawn with c lours, the change cannot be reversed.

5.Question.Give example to explain the difference between change that can or cannot be reversed.
Answer.Some changes can be reversed, like,
(1) Filling water with glass.
(2) Opening\Closing door.
Other change cannot be reversed, like,
(1) Cording of milk.
(2) Ripening of fruit.

6.Question. 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.No. The change in POP cannot be reversed.

7.Question.A bag of cement lying in the open gets wet 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. the changes which have occurred in the cement cannot be reversed