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प्रश्न
When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
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उत्तर
- When a candle burns, the melting of wax is a physical change and the burning of the candle is a chemical change. When the wax melts, only its physical properties change.
- Hence, it is a physical change. When a candle burns, its chemical properties and composition change, the melted wax turns into carbon dioxide and other substances and it cannot be obtained in its original form.
- It is a chemical change. Hence, when a candle burns, both physical and chemical changes take place.
Example:
When coal is broken into pieces and burned, both physical and chemical changes occur. Breaking coal into pieces is a physical change. The properties of coal do not change in this. Burning of coal is a chemical change. Due to burning, the chemical properties of coal change and new substances are formed.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Cutting of trees
Write true or false for the statement
Decomposition of leaves is a fast change.
Write true or false
Cutting of paper into pieces is a chemical change.
The rusting of an iron object is called :
Given reason:
Cutting of a cloth piece is a physical change, though it cannot be reversed.
Select the chemical changes from the following list of changes
The crystallisation of salt from its solution.
Water is the universal solvent. Why?
Classify the following as physical or chemical properties
Metallic sodium is soft enough to be cut with a knife.
Which of the following is not a physical change?
Cutting a log of wood into pieces is a chemical change.
