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प्रश्न
Give four difference between physical and chemical changes.
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उत्तर
The differences are Physical and Chemical Changes:
Physical change
- In a physical change no new substance is formed and the chemical composition of substance remains same. There are changes only in physical properties and state.
- Temporaiy change which can be reversed by simple physical methods.
- Weight of original substance doesn’t change
- Energy like heat, light etc. may or may not be absorbed or released
Chemical change
- In a chemical change new substance with entirely different chemical composition and properties is formed.
- Permanent change and irreversible
- Weight of original substances may increase or decrease
- Energy like heat, light etc. are given out or absorbed.
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संबंधित प्रश्न
Classify the following changes as physical or chemical:- melting of a solid (wax)
What is a physical change ? Give two examples of physical changes.
Photosynthesis is a natural process by which green plants manufacture food in the presence of sunlight.
State the conclusions which can be drawn, to represent photosynthesis as a physical or a chemical change.
Give reasons why – separation of mixtures e.g. iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.
Fill in the blank with the appropriate word of the statement given below:
Germination of seeds is considered a __________ change.
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
Select the chemical changes from the following list of changes
Rotting of eggs.
Give the reason why the following is considered as chemical changes.
A bright light is seen evolved when a strip of magnesium is heated.
Assertion: Burning of wood log to charcoal is a physical change.
Reason: The products formed of burning a piece of wood can be easily converted back to wood log.
Which of the following is a physical change?
