Changes Around Us is Chapter 6 taken from JKBOSE Class 6 Science. The given post is about the chapter Changes Around Us Class 6 Question Answers. You will get short notes and question answers in the chapter in this post. The previous post was about Chapter 5 Separation of Substances Question Answers. Let’s begin:
Changes Around Us Class 6th Question Answers
Overview of the Chapter
- CAN ALL CHANGES ALWAYS BE REVERSED?
- Reversible Changes.
- Irreversible Changes.
- COULD THERE BE OTHER WAYS TO BRING A CHANGE?
- Heating or Cooling.
- Mixing of two Substances.
CAN ALL CHANGES ALWAYS BE REVERSED?
There are so many things around us and changes happen around us all the time. Every change has a cause. The causes can bring changes in the shape, size, position, colour, temperature or internal structure of an object. Some of the changes that take place around us can be reversed while others cannot be reversed.
- Reversible Change: A change which can be reversed to get back the original substance is called reversible change. For example, stretching of a rubber band, change in the size of the balloon, change of water into vapours etc.
- Irreversible Change: A change which cannot be reversed or we cannot get back the original substances is called irreversible change. For example, changing milk into curd, iron onto rust, cooking food, making tea, and burning paper etc.
COULD THERE BE OTHER WAYS TO BRING A CHANGE?
- Heating or Cooling: The heating or cooling of a substance can bring change to it. A phenomenon in which a substance expands due to which its shape changes, is called expansion while a phenomenon in which a substance shrinks, i.e. its surface area as well as shape decreases is called contraction. For example, fixing an iron ring on the wooden handles of the tools, fixing the metal rim on a wooden wheel of a cart etc.
- Mixing of two Substances: When two or more substances are mixed together to bring a change. For example, sugar when mixed in water disappears and the water tastes sweet. This change is called dissolution.
Changes Around Us Class 6 Question Answers
- 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 by unfolding the dress. It is a reversible change.
- 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 change cannot be reversed because the broken toy cannot be joined together to get the same toy. It is a permanent and irreversible change.
- Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
|Change||Can be reversed (Yes/ No)|
|The sawing of a piece of wood|
|The melting of ice candy|
|Dissolving sugar in water|
|The cooking of food|
|The ripening of a mango|
|Souring of milk|
|Change||Can be reversed (Yes/ No)|
|The sawing of a piece of wood||No|
|The melting of ice candy||Yes|
|Dissolving sugar in water||Yes|
|The cooking of food||No|
|The ripening of a mango||No|
|Souring of milk||No|
- A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Ans. We can reverse this change if a picture is drawn with a pencil, we can erase it by using an eraser but if a picture is drawn by using a pen or paint then we cannot reverse this change.
- Give examples to explain the difference between changes that can or cannot be reversed.
Ans. Changes that can be reversed: The changes in which objects/materials can come back to their original state are called reversible changes.
- Melting of ice.
- Stretching of a rubber band.
- Drying of clothes.
- Knitting of a sweater.
Changes that cannot be reversed: The changes in which an object/material cannot come back to its original state are called irreversible changes. In such changes, new substances are formed.
- Burning of paper.
- Making of curd from milk.
- Boiling of an egg.
- Cooking of food.
- 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, this change cannot be reversed because a change in Plaster of Paris (POP) is a permanent chemical change. It is an irreversible change.
- 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 a change in cement is a permanent chemical change.
- Formation of snow is a physical change. Explain.
Ans. The formation of snow is a physical change because there is no new substance formed in this process. Snow is formed by the freezing of water vapours due to a decrease in temperature. When snow is heated, it changes back into the water. It is a reversible change.
- Burning of an incense stick is a chemical change. Explain.
Ans. Incense stick produces smelling gases and ash on burning. These are new substances having new properties. So, it is a chemical change. It cannot be reversed.
That’s all we have about Changes Around Us Class 6th Question Answers. Hope it has helped. Do share your views about this post in the comment section below.