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Question
What will you take into account while identifying the following?
A physical change in a substance.
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Solution
Physical changes are those changes in which only the forms of substances get modified; the chemical natures and compositions of the substances involved are not altered.
Characteristics:
- No new substance is formed during a physical change.
- Most physical changes can be reversed easily.
- The chemical composition of a substance undergoing physical change remains the same.
RELATED QUESTIONS
Which of the following are chemical changes?
- Growth of a plant
- Rusting of iron
- Mixing of iron fillings and sand
- Cooking of food
- Digestion of food
- Freezing of water
- Burning of candle
Tick the most appropriate answer.
5. Photosynthesis requires
- heat energy.
- wind energy
- sunlight.
- sound energy
Write true or false for the statement.
Deforestation is a man-made change
State the various conditions that favour the process of evaporation.
State one instance where water undergoes a physical change and one in which it undergoes a chemical change.
Is a change of state of matter – a physical or a chemical change. Give reasons.
Select the chemical changes from the following list of changes
Butter turning rancid
Give the reason why the following is considered as chemical changes.
Copper carbonate on heat gives copper oxide and carbon dioxide.
Match the examples of changes in List I with the correct type of change in List II.
| List I | List II |
| 1. Burning of paper | A: Physical change |
| 2. The ringing of an electric bell | B: Chemical change |
| 3. Curdling of milk | |
| 4. Electric light is switched on | |
| 5. Melting of butter |
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think rust is different from iron?
