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प्रश्न
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Slow and fast change.
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उत्तर
| Slow change | Fast change |
| (i) Changes which occur – very slowly over days, months, or years. | (i) Changes which occur – very rapidly in seconds or minutes. |
| (ii) Examples: Growth of a tree from a seed - a few years, tooth decay, change of seasons, growth of many rusting of iron | (ii) Examples: Occurrence of lightning - a few seconds, burning of paper or match, lighting a bulb, bursting of fireworks. |
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संबंधित प्रश्न
Fill in the blank.
Changes that occur in nature are called ........................
Melting of solid (wax) is a physical 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
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 a physical or a chemical change.
Boiling of water
Potassium chloride is added to water and stirred. A salt solution is obtained, which is then boiled, leaving behind a residue.
- Is the above change physical or chemical?
- Name the residue which remains behind after the salt solution is boiled.
- Is the change reversible or not reversible?
- Are the composition and properties of the original substance altered?
- Give a reason why the above experimentation would not be possible if calcium carbonate was taken in place of potassium chloride.
Give a reason why – Addition of zinc nitrate to water is a physical change but, the addition of zinc to dilute nitric acid is a chemical change.
In a solution of salt in water, water is the solute
When a woolen yarn is knitted to get a sweater, the change can be classified as ____________.
Cutting a log of wood into pieces is a chemical change.
