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Question
Give four reasons why the burning of a magnesium ribbon in the air is considered a chemical change.
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Solution
BURNING OF MAGNESIUM RIBBON is chemical change as It is
- Irreversible change
- New product with new properties is formed (MgO)
- It is a permanent change
- Composition is changed
- Energy is required to bring the change.
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RELATED QUESTIONS
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 |
Is burning a physical change or a chemical change? Why?
Name two reversible changes.
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.
Two chemical substances X and Y combine together to form a product P which contains both X and Y X + Y P
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following statements concerning X, Y and P are correct ?
- P is a compound
- X and Y are compounds
- X and Y are elements
- P has a fixed composition
Classify the following as physical or chemical change :
Condensation of steam
The rusting of an iron object is called :
Give a reason why rusting of iron is a chemical change but, the magnetization of iron is a physical change.
Natural changes which take place in nature on their own, are beyond the control of human being.
Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
