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प्रश्न
Name two reversible changes.
उत्तर
Melting of ice.
Dissolving of salt in water.
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संबंधित प्रश्न
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
State four differences between physical and chemical changes.
Fill in the blank
Chemical change occurs as a result of __________ between two substances.
Write true or false
Burning of paper and formation of curd are reversible changes.
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.
State one instance where water undergoes a physical change and one in which it undergoes a chemical change.
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.
Name the following.
The product obtained during a physical change when water converts from a liquid into a solid.
Physical Change: Boiling::Chemical Change: ______.
