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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
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उत्तर
- Plant growth: Five types of hormones are found in plants, which cause plant growth through chemical processes.
- Rusting of iron: Iron forms undesirable substances when it comes in contact with moisture.
- Cooking of food: Vapors arise while cooking food which is a chemical change.
- Digestion of food: There are chemicals inside our body for digestion.
- Burning of candle: Oxygen is required for this so it is a chemical change.
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संबंधित प्रश्न
Try segregating the things around you as pure substances or mixtures.
Photosynthesis cannot take place at night.
Fill in the blank
Revolution of the earth around the sun is a ________ change.
Fill in the blank.
Growing of a seedling into a plant is _______ change.
Match the columns.
| Column A | Column B |
| 1. a change which cannot be easily reversed | a. man-made change |
| 2 a change that repeats itself at regular intervals | b. chemical chang |
| 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 formed | e. irreversible change |
| f . slow change |
A physical change is temporary. Explain.
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
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.
Desirable and undesirable change.
Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and Step II are:
State whether the following statement is true or false:
Stretching of rubber bands is not a physical change.
