# Class 6 Science Chapter 6: Changes Around Us - NCERT Solutions

This page focuses on the complete NCERT solutions for Class 6 Science Chapter 6: Changes Around Us. This section provides detailed, easy-to-understand solutions for all the questions from this chapter. These Changes Around Us question answers will offer you valuable insights and explanations.

1. A lot of changes occurs in our environment day by day.
2. The changes which we can reverse, are called reversible changes. For example: burning of candle can be reversed by heating the wax again.
3. The changes which we cannot reverse, are called irreversible changes. For example: milk to curd, cutting of trees.
4. By heating, we can change the shape of the object. On heating expansion occurs.
5. By cooling, the size of the object or metal contracts.
6. The points at which any object starts to melt called its melting point.

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### Exercise 1 ( Page No. : 51 )

•  Q1 To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed? Ans: Yes, this change can be reversed. We usually shorten the length of our dress by folding it. It can be reversed by unfolding the length of the dress. So this change is an example of reversible changes. Q2 You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed? Ans: No, this changes cannot be reversed. If a toy is broken accidently than actually fixing it. After fixing, it will not be in the same condition as it was before. So this change cannot be reversed. Q3 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 Ans: 1. No It cannot be reversed because after sawing piece of wood would be in the same condition. 2. Yes This can be reversed by freezing the ice candy again. 3. Yes This can be reversed by vaporization. 4. No This cannot be reversed because we cannot change the cooked food again into raw materials. 5. No This cannot be reversed because ripening of mango is a natural process. 6. No This cannot be reversed because souring of milk is due to bacteria which is an irreversible change. Q4 A drawing sheet changes when you draw a picture on it. Can you reverse this change? Ans: No, we cannot reverse this change if the picture drawn on a drawing sheet with colours. But we can reverse it, if the picture is drawn by a pencil, then by erasing it we can reverse the change. Q5 Give examples to explain the difference between changes that can or cannot be reversed. Ans: The changes which can be reversed called as reversible changes. For example: Melting of ice Boiled water Draw a picture on paper by pencil Folding of clothes The changes which cannot be reversed called as irreversible changes. For example: Souring of milk A broken toy Cooking of food A tarn paper Q6 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: No, the change of POP cannot be reversed because when a thick coating of POP is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured immobilized. After drying it, POP undergoes a chemical reaction due to it, cannot be reversed. Q7 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: No, this change cannot be reversed because cement makes a hard product after mixing with water or when it comes in contact of moisture. This change cannot be reversed because it is due to chemical reaction.

### Key Features of NCERT Class 6 Science Chapter 'Changes Around Us' question answers :

• All chapter question answers with detailed explanations.
• Simple language for easy comprehension.
• Aligned with the latest NCERT guidelines.
• Perfect for exam preparation and revision.