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प्रश्न
Which of the following are chemical changes ?
- decaying of wood
- burning of wood
- sawing of wood
- hammering of nail into wood
विकल्प
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)
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उत्तर
(i) and (ii)
The processes in statements (i) and (ii) are chemical changes because decaying and burning causes formation of new compounds; thus they are chemical reactions. The processes in statements (iii) and (iv) are physical changes where no new compounds are formed.
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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
Write true or false for the statement.
Dissolving of solute in a solvent and rusting of iron are both physical changes.
A physical change is temporary. Explain.
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
Name a chemical change which takes place in presence of:
Make a list of different types of changes with example.
Classify the following as a physical or a chemical change.
Melting of wax
Given reason:
Freezing of water to ice and evaporation of water are physical changes.
When ice melts to form water, change occurs in its
In a solution of salt in water, water is the solute
