Physical and Chemical Changes - Worksheets

 CBSE Worksheet-01

Class – VII Science (Physical and Chemical Changes)

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1. Melting of ice is a
   1. Chemical change
   2. Physical change
   3. Periodic change
   4. Both physical and chemical change
2. Which of these is the smallest particle?
   1. An atom
   2. A molecule
   3. A speck of dust
   4. A water drop
3. Formation of a compound is
   1. Physical change
   2. Temporary change
   3. Chemical change
   4. Reversible change
4. Sea water is a
   1. Element
   2. Compound
   3. Mixture
   4. Molecule
5. Match the following

   Column A	Column B
   a. Burning of candle	i. Mixture
   b. Tearing of paper	ii. Compound
   c. Burning petrol	iii. Physical change
   d. Water	iv. Chemical change
   e. Air	v. Both physical and chemical change

6. Fill in the blanks
   1. Burning of magnesium is a ________ change.
   2. The changes that occur in chemical reactions are ________.
   3. Matters are classified as element, compound and ________.
   4. Chemical name of H2SO4 is ________.
   5. In chemical reaction reactants changes into ________.
7. What are physical changes? Give an example.
8. Why water is a compound but air is a mixture?
9. What is crystallization? Give it uses in day today life.
10. Classify as physical and chemical changes.
    1. Melting of ice
    2. Formation of water
    3. Tearing of paper
    4. Ripening of fruit
    5. Formation of curd from milk
    6. Stitching of cloth
11. Describe how crystals of copper sulphate are prepared.
12. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.

CBSE Worksheet-01
Class – VII Science (Physical and Chemical Changes)
Answer key

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1. b
2. a
3. c
4. c
5. (a) – (v), (b) – (iii), (c) – (iv), (d) – (ii), (e) – (i).
6. 1. Chemical
   2. irreversible
   3. mixture
   4. Sulphuric acid
   5. products.
7. A physical change is a change in which a substance undergoes a change in its physical properties only and no new substance is formed.
8. Water is a compound because it is formed from hydrogen and oxygen, which is irreversible, having different properties but air is a combination of different gases in any proportion.
9. The method of separation of pure crystals of a substance from its hot and super saturated solution on cooling is called crystallization.

10. Physical change	Chemical change
    Melting of ice	Formation of water
    Tearing of paper	Ripening of fruit
    Stitching of cloth	Formation of curd from milk

11. Crystals of copper sulphate are prepared by the method of crystallization. The process is as follows. A cupful of water is taken in a beaker. Few drops of dilute sulphuric acid are added to this. The water is then heated and when it starts boiling, copper sulphate powder is added with stirring. Copper sulphate powder should be added on till the solution becomes saturated. It is then filtered into a china dish and allowed to cool. The solution should be kept undisturbed. Slowly, the crystals of copper sulphate separate out.
12. When a candle burns, both physical and chemical changes take place.
    Physical change → Melting of wax
    Chemical change → Burning of wax
    Eating of food is another example where both physical and chemical changes occur simultaneously.
    Physical change → Breaking down of larger food particles into smaller particles
    Chemical change → Digestion of food