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प्रश्न
Write true or false
Earthquake is a desirable change.
विकल्प
True
False
उत्तर
False
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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.
Fill in the blank
change in which the substance can be brought back to its original state is called a ............... change.
Chemical changes are accompanied by changes in energy.
Write true or false
Cutting of paper into pieces is a chemical change.
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
Differentiate between a physical change and a chemical change with reference to – Energy change taking place during the respective change.
Match the following
| Sr. No. | A | B | C |
| 1. | Melting | Change of state from liquid to solid | Ticking of clock |
| 2. | Condensation | Change of state from liquid to gas | Formation of ice cube |
| 3. | Evaporation | Change of state from solid to liquid | Collecting flowers |
| 4. | Freezing | Change of state from gas to liquid | Ice cube to water |
| 5. | Periodic change | Occurs at irregular time intervals | Water to steam |
| 6. | Non-periodic change | Occurs at regular time intervals | Steam to water drops |
Water is known as a universal solvent. Why?
Classify the following as physical or chemical properties
The composition of a sample of steel is 98% iron, 1.5% carbon and 0.5% other elements.
Give an example of a physical change in which the color of the substance changes.
