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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
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
Is burning a physical change or a chemical change? Why?
Give the main differences between physical changes and chemical changes.
Which of the following are physical changes and which are chemical changes ?
Freezing of water
Give four difference between physical and chemical changes.
State whether the following statement is true or false. If false write the correct statement.
Melting of ice is an exothermic, irreversible chemical change.
Change is the law of nature which occurs in everyday life.
State when a substance [i.e. matter] undergoes a kind of change.
Give the reason why the following is considered as chemical changes.
A piece of magnesium strip is dropped into a beaker containing dilute hydrochloric acid.
Higher order Thinking question
Boiling of water is a physical change; but boiling of egg is a chemical change. Why?
Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and Step II are:
