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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.
संबंधित प्रश्न
Ripening of fruits is a desirable change.
State whether the following is physical or chemical changes.
burning of sugar —
State whether the following is physical or chemical changes.
respiration in living beings —
Classify the following as physical or chemical changes :
- Cooking of food
- Boiling of water
- Cutting of trees
- D0issolving salt in water
- Digestion of food
- Melting of ice
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
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
When ice melts to form water, change occurs in its
Digestion of food is a physical change.
Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
Fill in the blanks in the following statements using the words given in the box.
| rusted, colourful, substance, chemical, physical, reversible, iron oxide, object |
- Making sugar solution is a ______ change.
- A physical change is generally ______.
- Grinding of wheat grain changes its size. It is a ______ change.
- Iron benches kept in lawns and gardens get ______. It is a ______ change because a new ______ is formed.
