Page 43 - ICSE Chemistry 8

5. Natural and man-made changes
6. Physical and chemical changes
7. Condensa on and sublima on

B. Read the following paragraph. Iden fy the incorrect parts.
Physical change like freezing of water absorbs energy in the form of heat. This is because when water
freezes into ice, i.e., water changes its state from solid to liquid, the intermolecular force of a rac on
decreases thus decreasing the intermolecular distance. This is possible only when heat energy is absorbed
by the liquid or gas. Physical changes like combus on and diges on of food also involve absorp on of
energy.

C. Answer in detail.

1. Write the characteris cs of a physical change.
2. Give some examples of physical changes explaining why they are considered so.
3. With the help of an ac vity, show that mel ng of ice is a physical change.
4. Write the characteris cs of a chemical change.
5. Discuss why rus ng of iron and burning of paper are chemical changes.
6. Write a note on changes involving energy changes.

OBSERVE AND PERFORM

A. Observe the given image carefully and answer the following ques ons.
1. Label the image shown.

2. Name the phenomenon shown in the image.
3. Which type of change is shown: physical change or chemical change?
B. Iden fy the changes shown in the given images. Give reasons for your answers.

(i) (ii) (iii) (iv)

________________ ________________ ________________ ________________

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________________ ________________ ________________ ________________

________________ ________________ ________________ ________________

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