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प्रश्न
Compare the energy changes involved during a physical and a chemical change.
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उत्तर
- Physical change: No gain or loss of energy during physical change.
The energy required for completion of a physical change is released when the change is reversed. - Chemical change: Energy is either absorbed or evolved during the chemical change.
The energy in the form of light, percussion (pressure), or generally heat energy is required for a chemical change.
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संबंधित प्रश्न
Photosynthesis cannot take place at night.
Fill in the blank
Chemical change occurs as a result of __________ between two substances.
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
Give the main differences between physical changes and chemical changes.
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
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. |
Name the following.
The product of the chemical change in keeping a polished iron nail exposed to the atmosphere.
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. |
When solute is dissolved in a solvent it forms a solution.
Explain the characteristics of physical change with examples.
