RBSE Solutions for Class 6 Science Chapter 6 Changes Around Us

Rajasthan Board RBSE Solutions for Class 6 Science Chapter 6 Changes Around Us Textbook Exercise Questions and Answers.

RBSE Class 6 Science Solutions Chapter 6 Changes Around Us

RBSE Class 6 Science Changes Around Us InText Questions and Answers

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Question 1. 
Boojho has often noticed that road construction workers heat a black material (tar) for repairing a road. He wants to know whether the change caused in tor by heating, can be reversed?    
Answer:
The process is reversible, and can actually happen to some extent in hot weather, when the temperature gets very high. The tar then softens and melts at 150°C.

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Question 2. 
Paheli wants to know if you have ever seen a blacksmith making some tools. How does a blacksmith change a piece of iron into different tools? What change has taken place in iron, on being heated?
Answer:
The blacksmith heats a piece of iron till it becomes red - hot. It then becomes soft and is beaten into any shape. On being heated, the piece of iron undergoes several changes, such as increase in size (expansion) and increase in flexibility and softness.

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Question 3. 
Paheli asks if you have ever seen curd being set. A small quantity of curd is added to Warm milk. The milk is stirred and is set aside for a few hours at a warm place. In a few hours, the milk changes into curd. Cap this change be reversed?
Answer:
No, the conversion of milk into curd is an irreversible process as it involves a chemical changes in the composition of milk.

RBSE Class 6 Science Changes Around Us Textbook Questions and Answers

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 to its original length again by unfolding it.

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 as the toy generally cannot be joined again. 

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.
Answer:

Question 4. 
A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Answer:
In this case, the change can be reversible or not depending on what medium we choose to make the drawing.
For example - if we draw a picture on a drawing sheet with a pencil, we can get back the original drawing sheet by erasing the drawing with an eraser. However, if we draw with a pen or crayon or paint, then the original drawing sheet cannot be obtained back because we cannot erase ink / crayon / paint. Hence, in this case, the change cannot be reversed.

Question 5. 
Give examples to explain the difference between changes that can or cannot be reversed.
Answer:
1. If we inflate a balloon, the size and shape of the balloon undergoes a change. However, the original size and shape of the balloon can be obtained back by allowing the air to escape from the balloon. This means that the change that occurs by inflating a balloon can be reversed. But, if the balloon bursts after being inflated, then its original size and shape cannot be obtained back. Thus, in this case, the change cannot be reversed.

2. If we fold a piece of paper, then the shape and size of the paper undergoes a change. In this case, the original shape and size of the original paper can be obtained back. Thus, this change can be reversed. However, if we cut the paper into pieces, the change in the shape and size of the paper cannot be reversed.    

3. After we roll out a chapati from a ball of dough, the chapati can be converted back into a ball of dough. Thus, the change occurring here can be reversed. But, if we cook the chapati on a tawa, then it cannot be converted back into a ball of dough. Thus, the change is irreversible.

Question 6. 
A thick coating of Plaster of Paris (POP) paste 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 Plaster of Paris (POP) is a chemical change that cannot be reversed. When water is added to Plaster of Paris (POP), it changes to another substance and on drying, it hardens. Once the POP gets hardened, its shape cannot be changed.

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 that have occurred in the cement can be reversed?
Answer:
No, in this case, the changes cannot be reversed because oil mixing with water the cement hardeiis up and cannot be obtained back in its powder form. Hence, this is an irreversible change.