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Changes Around Us

Changes Around Us
science Square
Science Square

Many changes are taking place around us automatically. In the fields, the crops sown change from time to time. Sometimes we see leaves falling from trees, changes colour and dry out. The flowers bloom and then it withers away. Did you realise earlier that so many changes are taking place around you every moment?

Reversible and Irreversible Changes

Science Class 6 Changes Around Us Reversible  changes

Examples

  • First, take a balloon and blow it. Then take care that it does not burst. The shape and size of the balloon will change. Now, let the air escape the balloon. We will get back the balloon in the original condition.
  • First, take some dough and make a ball. Then try to roll out a roti. Maybe you are not happy with its shape and wish to change it back into a ball of dough again.

 

Science Class 6 Changes Around Us Irreversibles changes

 

Examples

  • First, take the same balloon, blow it to its full size and tie its mouth with a string tightly. Prick it with the pointed tip of your pencil. We will see it will burst. We can never get back the original balloon again.
  • Roll out a roti from the ball of dough and bake it on a tawa. We will never get the dough back.

 

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Quiz for Changes Around Us

Q.1

From the given options mark a process similar to height of human body

a) Weight of human body
b) Cutting of nails
c) Cutting of hair
d) Excretion process of human body

Q.2

From the given options mark the process that is reversible-

a) Diesel emission
b) Baked roti
c) Addition of water to cement
d) Expansion of balloon by blowing air in it

Q.3

From the given options mark process that is irreversible-

a) Expansion of balloon by blowing air in it
b) Expansion of copper
c) Flower blossoming from bud
d) Knotted laces

Q.4

Mark processes that can be reversed-

a) Cow dung to biogas
b) Idli from dough
c) Addition of water to pop
d) Glowing of bulbs

Q.5

Mark the processes that cannot be reversed-

a) Expansion of tube tyres when air is pressurized in it
b) Addition of water to pop
c) Evaporation of water
d) Washing of cloths

Q.6

Which among these is a reversible process?

a) Water mixed with milk
b) Breaking of mirror
c) Stretching of Elastic band.
d) Boiling of egg

Q.7

Why telephone lines are kept tight in summers.

a) Because they are always done in this way
b) Because the contract in winters
c) Because, to facilitate birds
d) Because they expand in summers

Q.8

In which among the following process the starting and end product is same?

a) diesel emission
b) petrol emission
c) boiling of water
d) printing on piece of paper

Q.9

When compared to our daily activities, choose which of the following depicts reversible changes?

a) working of blacksmith
b) fixing wooden handles on tools
c) fixing metallic rim on a wooden wheel
d) all of the above

Q.10

What are the changes that involve the liberation of heat?

a) exothermic changes
b) endothermic changes
c) physical change
d) rapid changes

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