Pick the change that can be reversed from the following.

1

(a)

Cutting of trees

(b)

Melting of ghee

(c)

Burning of candle

(d)

Blooming of flower

Salt can be separated from its solution (salt dissolved in water) because

1

(a)

mixing of salt in water is a change that can be reversed by heating and melting of salt

(b)

mixing of salt in water is a change that cannot be reversed

(c)

mixing of salt-in water is a permanent change

(d)

mixing of salt in water is a change that can be reversed by evaporation

Rolling of chapati and baking of chapati are the changes that 

1

(a)

can be reversed

(b)

cannot be reversed

(c)

can be reversed and cannot be reversed respectively

(d)

cannot be reversed and can be reversed respectively

Which one of the steps while burning a candle is not reversible?

1

(a)

Melting of solid wax

(b)

Wax vapour burn into flame

(c)

Liquid wax changes into vapours

(d)

All of the above

Which is a way to make a change happen?

1

(a)

Heating of substance

(b)

Mixing of substance with another substance

(c)

Cooling of substance

(d)

All of the above

Formation of rust on iron nail is a____________ change.

1

(a)

chemical

Formation of curd from milk is a ________________change.

1

(a)

chemical

Burning of paper is a ________change.

1

(a)

chemical

Heating and cooling any object is a ____________change

1

(a)

reversible

Change in weather takes place due to____________ of the sun.

1

(a)

heat

When ice melts to form water, then a change occurs in its state.

1

(a) False

(b) True

Paper burning into ash is a irreversible change.

1

(a) False

(b) True

Bursting of crackers are reversible change.

1

(a) True

(b) False

Formation of curd from the milk is a physical change.

1

(a) True

(b) False

The boiling of rice is a physical change.

1

(a) True

(b) False

Write the changes which cannot be reversed.

2

(a)

An object expands on heating. Write one use of it

2

(a)

Glowing of an electric bulb is a reversible change. Isn't it?

2

(a)

When the ice melts? Is it reversible?

2

(a)

Can we reverse the following changes? If yes, suggest the name of the method.
(a) Water into water vapour
(b) Water vapour into water
(c) Ice into water
(d) Curd into milk

3

(a)

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

3

(a)

Melting of wax can be reversed whereas burning of wax cannot be reversed. Explain.

3

(a)

Boojho's sister broke a white dove, a symbol of peace, made of Plaster of Paris (POP). Boojho tried to reconstruct the toy by making a powder of the broken pieces and then making a paste by mixing water. Will he be successful in his effort? Justify your answer.

3

(a)

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.

5

(a)

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:
(a) Simba blew balloons and put them on the wall.
(b) Some of the balloons got burst.
(c) Paheli cut colourful strips of paper and put them on the wall with the help of tape.
(d) She also made some flowers by origami (paper folding) to decorate the house.
(e) Her father made dough balls.
(f) Mother rolled the dough balls to make puries.
(g) Mother heated oil in a pan.
(h) 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.

5

(a)