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प्रश्न
Fill in the blank
Heat is ________ by a gas during the process of condensation.
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उत्तर
Heat is released by a gas during the process of condensation.
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संबंधित प्रश्न
Write true or false for the statement
Decomposition of leaves is a fast change.
Name a chemical change which takes place in presence of:
Write true or false
Dissolving of solute in a solvent and rusting of iron are both physical changes.
Separate the following into physical and chemical changes :
Sublimation of a solid, Decomposition of water into hydrogen and oxygen by passing electric current, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water
Differentiate between a physical change and a chemical change with reference to – Energy change taking place during the respective change.
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
Select the chemical changes from the following list of changes
Respiration in mammals.
Classify the following changes as physical and chemical changes
A rough piece of wood is sanded and polished resulting in change in texture, Rusting of a iron nail, Painting the grill, Bending a paper clip, Pounding silver into thin plate, Rolling the chappathi dough into thin wire, Occurrence of day and night, eruption of volcano, burning of matchstick, dosa from the batter, blinking of eyelids, occurrence of a thunderstorm, rotation of the earth, formation of eclipses.
| Sr. No. | Physical changes | Chemical changes |
| 1. | ||
| 2. |
Assertion: The explosion of fire cracker is a physical change.
Reason: A physical change is a reversible change.
Paheli’s mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a –
