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प्रश्न
Ice kept in a beaker, slowly melts and turns into water. The water in the beaker on solidification is freezing turns back to ice. Give four reasons why the change from ice to water and water back to ice is considered a physical change.
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उत्तर
Both changes are physical changes since
- The change is – temporary
- It is a reversible change
(heating and cooling reverse the change)
heating of ice – turns it into the water,
cooling of water – turns it back into ice - No new products are formed since both ice and water are chemical – ‘H20’
- Properties of the original substance are not altered.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Passing of electric current through water, and water breaking down into hydrogen and oxygen gases.
State whether the following is physical or chemical changes.
glowing of a bulb -
Write true or false
Earthquake is a desirable change.
What is a physical change ? Give two examples of physical changes.
Classify the following as a physical or a chemical change.
Melting of wax
Change is the law of nature which occurs in everyday life.
State when a substance [i.e. matter] undergoes a kind of change.
A change in which matter undergoes a change but the total mass of the substance is unaltered is a ______ change.
Match the examples of changes in List I with the correct type of change in List II.
| List I | List II |
| 1. Burning of paper | A: Physical change |
| 2. The ringing of an electric bell | B: Chemical change |
| 3. Curdling of milk | |
| 4. Electric light is switched on | |
| 5. Melting of butter |
Digestion of food is a physical change.
Mention some of the different conditions needed for chemical changes to occur.
