science - changes around us

Class 6 - Science

Changes Around Us

Q&A
Question:

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.



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Questions and Answers


Changes Around Us - Questions
1.

A drawing sheet changes when you draw a picture on it. Can you reverse this change?


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2.

You accidentally  dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?


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3.

Give two examples of slow changes.


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4.

Write some changes happening in our body.


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5.

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.


Answer
6.

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


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7.

To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?


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8.

What are slow and fast changes? Give examples.


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9.

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?


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10.

Give two examples of fast changes.


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11.

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?


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12.

Give two examples of irreversible changes.


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13.

Some common changes are given in Table 6.1. Which of these changes do you think can be reversed?


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14.

What is a physical change? Explain with example.


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15.

Can you change the shape of a eraser after erasing?


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16.

Give two examples of reversible changes.


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17.

Can you say deforestation is an irreversible or reversible change?


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18.

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


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19.

What happens when sugar is heated?


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20.

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


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21.

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


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22.

Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.

ncert-solutions-for-class-6th-science-chapter-6-changes-around-L 1.png3


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23.

What is a chemical change? Explain with example.


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24.

How does curd being set? Is this change reversible?


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25.

Give examples to explain the difference between changes that can or cannot be reversed.


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