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प्रश्न
Given reason:
Burning of paper is a chemical change.
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उत्तर
When a piece of paper is burnt a new substance ash is produced. Even when the burning is stopped, the ash cannot be changed back into paper. This shows that the formation of the ash from paper is a permanent and irreversible change.
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संबंधित प्रश्न
Tick the most appropriate answer.
3. Physical changes are
- permanent.
- periodic,
- temporary
- irreversible.
Tick the most appropriate answer.
4. Chemical changes involve
- change in shape.
- change in size.
- change in molecular composition.
- none of these
Write true or false for the statement
Decomposition of leaves is a fast change.
Classify the following changes as physical or chemical:- melting of a solid (wax)
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
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.
Name the following:
The final product of the physical change involved during the ‘melting of a piece of wax’.
Give a reason why
Freezing of water is a reversible change while burning of a candle – an irreversible change.
Select the chemical changes from the following list of changes
Butter turning rancid
