# Class 6 Science Chapter 6 Changes Around Us Extra Questions

CBSE Class 6 Science Chapter 6 Changes Around Us Extra Questions and Answers is available here. Students can learn and download the PDF of these questions for free. These extra questions and answers are prepared by our expert teachers as per the latest NCERT textbook and guidelines. Learning these extra questions will help you to score excellent marks in the final exams.

## Changes Around Us Class 6 Science Extra Questions and Answers

1: Some changes can be reversed, some cannot be reversed. (TRUE/FALSE)

2: If we sharp a pencil its length decreases. Can this change be reversed?

3: After baking a roti on tawa, it is not possible to get back the ball of dough again. What type of change is this?
Answer: This is a change which cannot be reversed.

4: A potter changes or shapes a lump of clay into a pot. Can this change be reversed?

5: Give an example of reversible change.
Answer: The shape and size of balloon can be changed by blowing it.

6: A man is carrying a mirror. He suddenly drops a mirror and mirror is broken. Can this change be reversed?

7: Raw egg is boiled. We can reverse this change. (TRUE/FALSE)

8: If we blow a balloon. The shape and size of balloon has changed. This is a _____________ change.

9: After making a ball with dough, a person rolls out a roti. Can he now change it back to a ball of dough?

10: A paper is changed into a shape of bat by cutting it. What kind of change it is?
Answer: This is a change which cannot be reversed

11: A sheet of paper is changed into a toy aeroplane by folding it. This is a reversible change. (TRUE/FALSE)

12: Butter is changed into dosa. This is _____________.(reversible change/irreversible change)

13: Cold milk is heated and it becomes hot. Which type of change it is?

14: A sheet of paper is folded to make an aeroplane. Then this paper is unfolded again. Is the size of paper same as before or after making an aeroplane?

15: Bud to flower is a ___________ change. (reversible/irreversible)

16: A copper wire is folded to form a loop. Can this change be reversed?

17: Wet clothes get dry. This is a reversible change because ______________.
Answer: They can again get wet if we put them in water.

18: By using woollen yarn a lady knitted a sweater. Can this change be reversed?

19: Milk to paneer is a reversible change. (TRUE/FALSE)

20: Biogas is prepared from cow dung. Can this change be reversed?

21: Metal expands on heating. (TRUE/FALSE)

22: If cold water is poured over a hot metal ring it___________ .(expand/contracts)

23: Water vapour changes into _________when it is cooled.

24: When metal ring is heated, it ___________.

25: When water is heated, it changes into _____________.

26: On lightening the candle the length of candle decreases. Can this change be reversed?

27: A boy paints an apple on a piece of paper. Do you think that change in piece of paper can be reversed?

28: Conversion of water vapour into liquid water is a _____________ change.

29: Take a glass of water. Dissolve two tea spoons sugar in it. These are changes in water which can _________. (Be reversed/not be reversed).

30: A rope is tied around a box. The shape of rope changes. What kind of change is this?
Answer: This is a reversible change.

31: When we burn a piece of wood, what changes occurs in it?
Answer: It turns into ash. It is not a reversible change.

32: Can change due to dissolving salt in water be reversed?

33: By heating a substance or mixing it with some other substance, changes may occur in it. (TRUE/FALSE)

34: Cooking changes the flavour of vegetables. Can we reverse this change?

35: All changes around us can be reversed. (TRUE/FALSE)

36: Evaporation of water is reverse of condensation of water. (TRUE/FALSE)

37. Give two examples of slow changes.
(b) Ripening of fruits.

38. Give two examples of fast changes.
(b) Rolling out roti from dough ball.

39. Give two examples of reversible changes.
Answer: (a) Drying of wet clothes
(b) Heating of milk.

40: Give two examples of irreversible changes.
(b) Cooking of food.

41. Can you say deforestation is an irreversible or reversible change?
Answer: It is an irreversible change.

42. Does the size of the paper change after making an aeroplane by folding it or by cutting it?

43. Can you change the shape of an eraser after erasing?

### Short Type Questions and Answers

1: Why is ring of iron blade heated before fixing it into handle of a tool?

Answer: Ring of iron blade heated before fixing it into handle of a tool because on heating ring becomes slightly larger in size, therefore it expand and handle fits easily into it.

2: What happens when we keep on heating water in a pan?

Answer: When we keep on heating water in a pan, the quantity of water in the pan decreases.

3: Write two examples of changes which can be reversed.

Answer:  a) Drying the wet clothes.
b) Liquid water into water vapour.

4: Why is the quantity of water in a pan decreases when we keep on heating it?

Answer: The quantity of water in a pan decreases when we keep on heating it because water changes into its vapour

5: Which of the following are reversible changes:
a. Breaking a toy.
b. Melting of ice cream.
c. Preparing curd from milk
d. Changing shape of cloth by folding it.

Answer: Melting of ice cream and changing shape of cloth by folding it.

6: Write two examples of changes which cannot be reversed?

b) Preparing curd from milk.

7: Write True or false:
a. Ripening of apple is a reversible change
b. Metal expands on heating.
c. Shortening the length of dress by folding it is not a reversible change.
d. Cooling the hot milk is a reversible change.

b. True
c. False
d. True

8: Conversion of water into water vapour is a reversible change. Why?

Answer: Conversion of water into water vapour is a reversible change because water vapour when cooled gets converted into liquid water again.

9: A blacksmith heats a piece of iron till it becomes red hot and then beats it into a desired shape. What changes have taken palace in iron on heating?

Answer: An iron expands and becomes soft on heating. Then it can be changed into desired shape.

10: On lightening the candle its length decreases. How can this be reversed?

Answer: If we take some wax in a pan and heat it, this change can be reversed.

11: Melting of ice is a reversible change. Why?

Answer: Melting of ice is a reversible change because on melting ice changes into water but the water can again be freezed to change it into ice

12: How can a change occur in a substance?

Answer: A change may occur by heating a substance or by mixing it with some other.

13: What changes occur in a match stick used for lightening? What type of change is it?

Answer: Match stick changes into ash and this is a change that cannot be reversed.

14: We dissolve salt in water. How can we reverse this change?

Answer: We can reverse this change by evaporation of water by which salt can be obtained. Water vapours are condensed to get liquid water.

15: How is metal rim fixed on a wooden wheel of a cart? How is the changes made in that metal?

Answer: Metal rim is made slightly smaller than the wooden wheel. On heating rim expands and fits into wheel. Cold water is then poured over rim, which contracts and fits tightly onto the wheel.

16: How the iron blade is fixed into a wooden handle in tools used to dig the soil?

Answer: Iron blade of tools has a ring in which the wooden handle is fixed. Normally the ring is slightly smaller in size than wooden handle. To fix handle ring is heated and it expands. Now handle easily fits into the ring. When ring cools down it contracts and fits into handle

17. Why does a blacksmith heat the metal rim to fix it on a cart wheel?

Answer: A blacksmith heats the metal rim to fix it onto a cart wheel because a metal rim is made slightly smaller. On heating, the rim expands and fits onto the wheel. Then on cooling, the rim contracts and fits tightly onto the wheel.

18. What are slow and fast changes? Give examples.

Answer: The changes which take place in a long period of time are called slow changes whereas that changes which take place in a short period of time are called fast changes.

Examples:
(a) Rusting of iron, formation of day and night, ripening of fruits, growing of trees are slow changes.
(b) Burning of paper, stretching of rubber band, blowing of balloons, bursting of crackers are fast changes.

19. Classify the following into slow and fast changes:
(i) Spinning of top
(ii) Formation of day and night
(iii) Formation of curd from milk
(iv) Change of season
(v) Making curd from milk by adding lemon juice.

(i) Fast change
(ii) Slow change
(iii) Slow change
(iv) Slow change
(v) Fast change.

20. Classify the following as slow or fast change:
(i) Bearing of heart
(ii) Change of seasons
(iii) Burning of paper
(iv) Weathering of rocks
(v) Melting of wax
(vi) Cooking of food
(vii) Burning of wax
(viii) Melting of ice cream
(ix) Curding of milk
(x) Formation of day and night

(i) Fast
(ii) Slow
(iii) Fast
(iv) Slow
(v) Fast
(vi) Slow
(vii) Fast
(viii) Fast
(ix) Slow
(x) Slow

21. Write some changes happening in our body.
(a) Our nails grow
(b) Our hair grows
(c) We grow taller
(d) Our weight increases.

22. What is a physical change? Explain with example.

Answer: The changes in which only physical properties of substances are changed and no new substance is formed is called physical change. It is a reversible change. Example: Boiling and freezing of water.

23. What is a chemical change? Explain with example.

Answer: The changes in which new substance with new chemical properties are formed are called chemical changes.
Example: Reaction between washing soda and lemon juice in which C02 and other substances are formed.

24. What happens when sugar is heated?
Answer: When sugar is heated continuously then a black powdery substance is formed. This is a chemical change.

1. Explain how a metal rim slightly smaller than a wooden wheel can be fixed on it.

Answer: The metal rim is always made slightly smaller than the wooden wheel. The metal rim is heated. On heating, the rim expands and fit onto the wheel. Cold water is then poured over the rim. Due to cooling the metal rim contracts and fits tightly onto the wheel.

2. How does curd being set? Is this change reversible?

Answer: A small quantity of curd is added to warm milk. The milk is stirred and is set aside undisturbed for a few hours at a warm place. In a few hours, the milk changes into curd. Curd formed from milk cannot be changed into milk again. So, this an irreversible (cannot be reversed) change.

3. Tearing of paper is said to be a change that cannot be reversed. What about paper recycling?

Answer: Paper recycling is also an irreversible process. This is because we do get paper on paper recycling but it is not the same original paper was used. The colour and texture of the paper changes.

4. Is steaming of idli batter to make idli a reversible change? Give reasons to support your answer.

Answer: No, because once the idli batter is steamed, it undergoes a chemical change which is irreversible.

5. Differentiate between slow and fast change.