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प्रश्न
Give three reasons why melting of wax, is considered a physical change while burning of a candle, a chemical change.
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उत्तर
Melting of wax is a temporary and reversible change on cooling, wax solidifies, and no new product is formed while burning of a candle is a permanent change i.e. products are not convertible, a new substance is formed having different composition & different properties.
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संबंधित प्रश्न
Which of the following are chemical changes?
- Growth of a plant
- Rusting of iron
- Mixing of iron fillings and sand
- Cooking of food
- Digestion of food
- Freezing of water
- Burning of candle
Classify the following changes as physical or chemical:-boiling
Write true or false
Rusting of iron is a chemical change.
State the Differences Between a Physical Change and a Chemical Change.
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.
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
Fill in the blank.
The reaction in which energy is evolved is called
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
Digestion of food is a physical change.
Filling up a balloon with hot air is a _______ change.
