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प्रश्न
Try segregating the things around you as pure substances or mixtures.
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उत्तर
- Pure substance: Distilled water, diamond; graphite, gold, sulphur.
- Mixture: Curd, ice cream, kerosene oil, cooking oil, steel, vulcanised rubber, solder wire (an alloy of lead and tin).
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संबंधित प्रश्न
Match the columns
| column A | coulmn B |
| 1. A change which cannot be easily reversed | a. man-made change |
| 2.A change that repeats itself at regular intervals | b. chemical change |
| 3. A change that is made by humans | c. physical change |
|
4. A change in which the original substance cannot be obtained |
d. periodic change |
| 5. A change where no new substance is formade | e. irreversible change |
| f. slow change |
Write true or false for the statement.
Deforestation is a man-made change
State whether the following is physical or chemical changes.
shaping a piece of glass —
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.
Which of the following are physical changes and which are chemical changes?
Burning of candle wax, Melting of candle wax, Mixing of iron filings and sand, Burning of wood, Breaking a piece of chalk, Burning a piece of paper, Cutting a piece of paper.
Select the correct answer from the choice given below to complete the sentence
A change in which a substance retains its identity is a
______ change.
Select the correct answer from the choice given below to complete the sentence
The matter is added or removed during a ____________ change.
Give the reason why the following is considered as chemical changes.
Copper carbonate on heat gives copper oxide and carbon dioxide.
Filling up a balloon with hot air is a _______ change.
______ is the substance that is dissolved in a solvent.
