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प्रश्न
Select the chemical changes from the following list of changes
The crystallisation of salt from its solution.
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उत्तर
The crystallisation of salt from its solution is a PHYSICAL change as only state changes (crystals are formed), the composition does not change, is reversible, no change in mass takes place.
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संबंधित प्रश्न
Changes in which only ______ properties of a substance change are called physical changes.
Tick the most appropriate answer.
5. Photosynthesis requires
- heat energy.
- wind energy
- sunlight.
- sound energy
Solve this crossword by using the clues that follow.
Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.
Down
1. It is the change that takes place in case of swinging pendulum of a clock.
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change
Given reason:
Cutting of a cloth piece is a physical change, though it cannot be reversed.
Give four difference between physical and chemical changes.
Give a reason why – Addition of zinc nitrate to water is a physical change but, the addition of zinc to dilute nitric acid is a chemical change.
Select the chemical changes from the following list of changes
Rotting of eggs.
Select the chemical changes from the following list of changes
Preparation of carbon dioxide from calcium carbonate & dilute hydrochloric acid.
Grinding of wheat grain changes its size. It is a ____________ change.
Cutting a log of wood into pieces is a chemical change.
