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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
Tick the most appropriate answer
2. Melting of ice is a
- reversible change
- irreversible change
- chemical change
- none of these
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
Classify the following changes as physical or chemical:-boiling
Tick (√) the correct alternative from the choice given for the following statement
Which one of the following is volatile in nature ?
Tick the most appropriate answer.
Photosynthesis requires
Fill in the blank.
The reaction in which energy is evolved is called
Given reason:
Freezing of water to ice and evaporation of water are physical changes.
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.
Periodic and non-periodic 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:
