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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:
Melting of butter in a pan
Fill in the blank.
Heat is .................... by a gas during the process of condensation.
A physical change is temporary. Explain.
Classify the following changes as physical or chemical:- photosynthesis in plants
Match the columns.
| Column A | Column B |
| 1. a change which cannot be easily reversed | a. man-made change |
| 2 a change that repeats itself at regular intervals | b. chemical chang |
| 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 formed | e. irreversible change |
| f . slow change |
Classify the Following as a Physical Or a Chemical Change.
Making of a Sugar Solution
State why addition of sodium chloride to water is considered a physical change, while addition of dilute sulphuric acid to zinc is considered a chemical change.
In a solution of salt in water, water is the solute
Distinguish physical and chemical changes.
Tearing of sheet of paper into pieces is ______ By the process of Heating of water, change.
