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

An iron ring is heated. Which of the following statements about it is incorrect?

1

(a)

The ring expands

(b)

The ring almost comes to the same size on cooling

(c)

The change in this case is reversed

(d)

The ring changes its shape and the change cannot be reversed

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

An iron ring is heated. Which of the following statements about it is incorrect?

1

(a)

The ring expands

(b)

The ring almost comes to the same size on cooling

(c)

The change in this case is reversed

(d)

The ring changes its shape and the change can not be reversed

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

Liquids _____ on freezing

1

(a)

solidify

Burning of candle is ________ process

1

(a)

irreversible

Water change in vapour when cooled.

1

(a) True

(b) False

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

Drying of clothes is a physical and an irreversible change

1

(a) True

(b) False

Physical changes can not be reversed while chemical changes can be reversed

1

(a) True

(b) False

A change occurs during the growth of plants. What type of change it is?

2

(a)

An object expands on heating. Write one use of it

2

(a)

Suppose you have dropped your favorite toy and broken it. Can this change be reversed?

2

(a)

Explosion of a cracker is a chemical change. Explain

3

(a)

How does a blacksmith change a piece of iron into different tools?

3

(a)

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

3

(a)

Some bags of cement lying on the floor get wet due to the leakage of tap water in the room. The next day, they are kept in the sunshine. Do you think the changes, that have occurred in the cement could be reversed?

5

(a)

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

8

(a)

In the given table, check whether the given changes can be reversed or not.

Change	Can be reversed
Raw egg to boiled egg	Yes/No
Batter to Idli
Wet clothes to dry clothes
Woollen yarn to knitted sweater
Grain to its flour
Cold milk to hot milk
Straight string to a coiled string
Bud to flower
Milk to paneer
Cowdung to biogaes
Stretched rubber band to its
normal size
Ice cream to molten ice cream

7

(a)