Page 42 - ICSE Chemistry 8

D. Match the columns.
Column A Column B

1. Periodic changes (a) A dull bri le brown substance
2. Fast changes (b) Release of heat and carbon dioxide

3. Chemical change (c) Changes occurring a er a regular interval of me
4. Rust (d) Physical change which absorbs heat

5. Fermenta on (e) Change in composi on of a substance
6. Mel ng of ice (f) Changes occurring very quickly

SHORT AND PRECISE

A. Show the given text in the form of fl owcharts.
1. Classifi ca on of changes
2. Physical and chemical changes

B. Give reasons for the following statements.

1. No change of mass occurs during a physical change.
2. Breaking of a plate is considered to be a physical change.
3. Drying of wet clothes is a physical change.

4. Diges on of food is a chemical change.
5. Boiling of water is a physical change.
6. Fermenta on is a chemical change.

C. Answer in short.

1. Give any four examples of changes taking place in your surroundings. Classify these changes as
physical or chemical.
2. Why is burs ng of a balloon an irreversible change?
3. What is the diff erence between mel ng and freezing?
4. What happens during a chemical change?

5. Give any two examples of chemical changes.
6. List a few changes in which energy is absorbed.

AT LENGTH

A. Diff eren ate between the following.

1. Reversible and irreversible changes
2. Periodic and non-periodic changes
3. Desirable and undesirable changes

4. Slow and fast changes

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