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NCERT Exemplar · Class 6 · Science

Chapter 6: Changes Around Us

Practice each question, then open the answer or worked solution.

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Long Answer Questions

6 questions
Q15Written answer

Give one example in each case

(a) Change which occurs on heating but can be reversed.

(b) Change which occurs on heating but cannot be reversed.

(c) Change which occurs on cooling but can be reversed.

(d) Change occurs on mixing two substances, but can be reversed.

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Worked solution

Ans: An iron rod's heating is a reversible process

Ans: Baking chapati is an irreversible change.

Ans: Formation of ice from water is reversible.

Ans: Formation of salt solution.

(e) Change which occurs on mixing two substances, but cannot be reversed.

Ans: Mixing of cement and water is an irreversible change.


Q16Written answer

A potter working on his wheel-shaped a lump of clay into a pot. He then baked the pot in an oven. Do these two acts lead to the same kind of changes or different? Give your opinion and justify your answer.

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Worked solution

Ans:  The two actions lead to different kinds of changes-

1. Since only the physical property of the lump of clay is modified when it is moulded into a pot, it is a reversible process.

2. When the pot is baked in the oven, its chemical properties are changed, thus, it is an irreversible process.


Q17Written answer

Conversion of ice into water and water into ice is an example of change which can be reversed. Give four more examples where you can say that the changes can be reversed.

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Worked solution

Ans: Examples of reversible change. 

i. Inflating a balloon.

ii. Melting of wax.

iii. Folding of a paper.

iv. Blowing a balloon.


Q18Written answer

Change of a bud into a flower is a change which cannot be reversed. Give four more such examples.

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Worked solution

Ans: Examples of an irreversible change

i. Bursting the blown balloon.

ii. Grinding a vegetable or a fruit

iii. Cooking a vegetable.

iv. Burning a candle.


Q19Written answer

Paheli mixed flour and water and (i) made a dough, (ii) rolled the dough to make a chapati, (iii) baked the chapati on a pan, (iv) dried the chapati and ground it in a grinder to make powder. Identify the changes (i) to (iv) as the changes that can be reversed or that cannot be reversed.

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Worked solution

Ans: Reversible changes-

(ii) Rolled the dough to make a chapati

Irreversible changes-

(i) made a dough, 

(iii) baked the chapati on a pan, 

(iv) dried the chapati and ground it in a grinder to make powder.


Q20Written answer

It was Paheli’s birthday, her brother Simba was helping her to decorate the house for the birthday party and their parents were also busy making other arrangements. Following were the activities going on at Paheli’s home:

(i) Simba blew balloons and put them on the wall.

(ii) Some of the balloons got burst.

(iii) Paheli cut colourful strips of paper and put them on the wall with the help of tape.

(iv) She also made some flowers by origami (paper folding) to decorate the house.

(v) Her father made dough balls.

(vi) Mother rolled the dough balls to make puris.

(vii) Mother heated oil in a pan.

(viii) Father fried the puries in hot oil. 

Identify the activities at Paheli’s home as those that can be reversed and those which cannot be reversed.

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Worked solution

Ans: Reversible changes-

(i) Simba blew balloons and put them on the wall

(iv) She also made some flowers by origami (paper folding) to decorate the house.

(v) Her father made dough balls.

(vi) Mother rolled the dough balls to make puris.

(vii) Mother heated oil in a pan. 

Irreversible changes-

(ii) Some of the balloons got burst.

(iii) Paheli cut colourful strips of paper and put them on the wall with the help of tape.

(viii) Father fried the puries in hot oil. Identify the activities at Paheli’s home as those that can be reversed and those which cannot be reversed.


Importance of Learning From NCERT Science Exemplar Problems

Science Exemplar Questions & Solutions were introduced to class 6th students to test their analytical thinking, comprehension, and problem-solving ability. This is also the section because of which different education platforms give priority to NCERT Science Exemplar books and solutions. If we talk of the science chapter of class 6th Changes Around Us then the exemplar problems are not only important for examinations but they improve the base for the students. 


The exercises given on the NCERT Science Exemplar books provide students to take a self-assessment even when they are not at school. In addition to that, students also master the techniques of solving complex problems and situation-based problems where they use their mental skills, understanding skills to find answers to your question. So if you are a student in class 6th or a parent who is looking for the best assistance then class 6th Science exemplar book problems and solutions are your best available option.