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प्रश्न
What will you take into account while identifying the following?
A physical change in a substance.
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उत्तर
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.
संबंधित प्रश्न
Classify the following changes as physical or chemical: curdling of milk
Classify the following changes as physical or chemical:-boiling
Write true or false
Burning of sugar is a temporary change.
Classify the following as a physical or a chemical change.
Burning of paper
Differentiate between a physical change and a chemical change with reference to – Nature of change is temporary and reversible or permanent and irreversible.
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.
Potassium chloride is added to water and stirred. A salt solution is obtained, which is then boiled, leaving behind a residue.
- Is the above change physical or chemical?
- Name the residue which remains behind after the salt solution is boiled.
- Is the change reversible or not reversible?
- Are the composition and properties of the original substance altered?
- Give a reason why the above experimentation would not be possible if calcium carbonate was taken in place of potassium chloride.
Stretching gold coin into a ring is a ______ change.
Paheli’s mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a –
