Try out the following activities and decide whether they are physical change or chemical change. S.No. Process Observation Physical or chemical change 1 Add sugar to a glass of water and stir for a while. What happens to the sugar after a few minutes of stirring? 2 Light up a candle. Hold a small piece of paper with forceps near the fire. What happens to the paper? 3 Place the bottle of coke in an open area where spillages can be cleaned easily. Now put two tea spoon full of baking powder in the bottle of coke. Give it a stir. What do you observe? 4 Cut open an apple with a knife and keep for half an hour. Observe what happens.

1. Physical change - No new substance is formed. Observation - Sugar will be dissolved as it is soluble in water. The making of sugar solution is a reversible change. 2. Chemical change - A change in energy occurs in the form of heat and light. Observation - Paper will burn. As it is combustible and gets converted into ash that has different compositions. 3. Chemical change - A new substance forms. Carbon dioxide gas will be released. Observation - A spray of effervescence will come out. Carbonated water is formed by dissolving the carbon dioxide. 4. Chemical change - A new substance is formed in the form of brown colour on the apple. Observation - Apple colour will turn brown. Food gets rancid due to reaction with oxygen.

E M B I B E

Expanded Universal Science 7>Chapter 7 - Physical and Chemical Changes>ASSESSMENT ZONE>Q C

MEDIUM

7th CBSE

IMPORTANT

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Classify the following change as physical or chemical:
Shredding paper

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Important Questions on Physical and Chemical Changes

HARD

7th CBSE

IMPORTANT

Expanded Universal Science 7>Chapter 7 - Physical and Chemical Changes>ASSESSMENT ZONE>Q C

Classify the following changes as physical or chemical:
Sublimation of dry ice into carbon dioxide gas.

HARD

7th CBSE

IMPORTANT

Expanded Universal Science 7>Chapter 7 - Physical and Chemical Changes>ASSESSMENT ZONE>Q C

Classify the following change is a physical or chemical:
Hammering wood together to build a playhouse.

HARD

7th CBSE

IMPORTANT

Expanded Universal Science 7>Chapter 7 - Physical and Chemical Changes>ASSESSMENT ZONE>Q C

Classify the following changes as physical or chemical:
Sugar caramelises on heating

HARD

7th CBSE

IMPORTANT

Expanded Universal Science 7>Chapter 7 - Physical and Chemical Changes>ASSESSMENT ZONE>Q D

Try out the following activities and decide whether they are physical change or chemical change.

S.No.	Process	Observation
1	Add sugar to a glass of water and stir for a while.	What happens to the sugar after a few minutes of stirring?
2	Light up a candle. Hold a small piece of paper with forceps near the fire.	What happens to the paper?
3	Place the bottle of coke in an open area where spillages can be cleaned easily. Now put two tea spoon full of baking powder in the bottle of coke. Give it a stir.	What do you observe?
4	Cut open an apple with a knife and keep for half an hour.	Observe what happens.