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प्रश्न
Given reason:
Burning of paper is a chemical change.
उत्तर
When a piece of paper is burnt a new substance ash is produced. Even when the burning is stopped, the ash cannot be changed back into paper. This shows that the formation of the ash from paper is a permanent and irreversible change.
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संबंधित प्रश्न
Changes in which only ______ properties of a substance change are called physical changes.
Tick the most appropriate answer.
4. Chemical changes involve
- change in shape.
- change in size.
- change in molecular composition.
- none of these
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
Define physical change. Give two examples for the above changes.
State whether the following is physical or chemical changes.
growing of a piglet into a pig —
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
Give the main differences between physical changes and chemical changes.
Select the chemical changes from the following list of changes
Change of seasons
Name the following.
The product obtained during a physical change when water converts from a liquid into a solid.
Higher order Thinking question
Boiling of water is a physical change; but boiling of egg is a chemical change. Why?
