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प्रश्न
Try segregating the things around you as pure substances or mixtures.
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उत्तर
- Pure substance: Distilled water, diamond; graphite, gold, sulphur.
- Mixture: Curd, ice cream, kerosene oil, cooking oil, steel, vulcanised rubber, solder wire (an alloy of lead and tin).
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संबंधित प्रश्न
Chemical changes are accompanied by changes in energy.
Classify the following changes as physical or chemical:- melting of a solid (wax)
Classify the following as physical or chemical changes :
- Cooking of food
- Boiling of water
- Cutting of trees
- D0issolving salt in water
- Digestion of food
- Melting of ice
Define a chemical change. Give two examples of the above changes.
State why addition of sodium chloride to water is considered a physical change, while addition of dilute sulphuric acid to zinc is considered a chemical change.
Give a reason why
Freezing of water is a reversible change while burning of a candle – an irreversible change.
Give a reason why
Change of seasons is a periodic change while the change of weather is a non-periodic change.
Select the chemical changes from the following list of changes
The crystallisation of salt from its solution.
Select the correct answer from the choice given below to complete the sentence
A change in which a substance retains its identity is a
______ change.
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.
