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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.
Chapter 6 Changes Around Us
- A lot of changes occurs in our environment day by day.
- The changes which we can reverse, are called reversible changes. For example: burning of candle can be reversed by heating the wax again.
- The changes which we cannot reverse, are called irreversible changes. For example: milk to curd, cutting of trees.
- By heating, we can change the shape of the object. On heating expansion occurs.
- By cooling, the size of the object or metal contracts.
- The points at which any object starts to melt called its melting point.
Download pdf of NCERT Solutions for Class Science Chapter 6 Changes Around Us
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Exercise 1 ( Page No. : 51 )
Popular Questions of Class 6 Science
- Q:-
Draw (a) a leaf, (b) a taproot and (c) a flower, you have studied for Table 7.3.
- Q:-
You are given an iron strip. How will you make it into a magnet?
- Q:-
Name two foods each rich in:
(a) Fats
(b) Starch
(c) Dietary fibre
(d) Protein - Q:-
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?
- Q:-
Tick (√) the statements that are correct.
(a) By eating rice alone, we can fulfill nutritional requirement of our body. ( )
(b) Deficiency diseases can be prevented by eating a balanced diet. ( )
(c) Balanced diet for the body should contain a variety of food items. ( )
(d) Meat alone is sufficient to provide all nutrients to the body. ( ) - Q:-
List all items known to you that float on water. Check and see if they will float on an oil or kerosene.
- Q:-
Name the part of the plant which produces its food. Name this process.
- Q:-
Why can a pace or a footstep not be used as a standard unit of length?
- Q:-
Given below are the names of some objects and materials:
Water, basket ball, orange, sugar, globe, apple and earthen pitcher Group them as:
(a) Round shaped and other shapes
(b) Eatables and non eatables - Q:-
Name two items that are made from coconut fibre.
Recently Viewed Questions of Class 6 Science
- Q:-
Is it possible for you to recognize the leaves without seeing them? How?
- Q:-
When does a drought occur?
- Q:-
What is winnowing? Where is it used?
- Q:-
Explain, why speed is important for survival in the grasslands for animals that live there. (Hint: There are few trees or places for animals to hide in grasslands habitats.)
- Q:-
Can you find a plant in your house or in your neighborhood, which has a long but a weak stem? Write its name. In which category would you classify it?
- Q:-
Discuss :
(a) Is garbage disposal the responsibility only of the government?
(b) Is it possible to reduce the problems relating to disposal of garbage? - Q:-
Correct the following statements and rewrite them in your notebook.
(a) Stem absorbs water and minerals from the soil.
(b) Leaves hold the plant upright.
(c) Roots conduct water to the leaves.
(d) The number of petals and sepals in a flower is always equal.
(e) If the sepals of a flower are joined together, its petals are also joined together.
(f) If the petals of a flower are joined together, then the pistil is joined to the petal. - Q:-
(a) Collect pieces of different kinds of paper. Find out which of these can be recycled.
(b) With the help of a lens look at the pieces of paper you collected for the above question. Do you see any difference in the material of recycled paper and a
new sheet of paper ? - Q:-
Which of the non-living things listed below, were once part of a living thing?
Butter, Leather, Soil, Wool, Electric bulb, Cooking oil, Salt, Apple, Rubber
- Q:-
You are given an iron strip. How will you make it into a magnet?
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