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प्रश्न
What will you take into account while identifying the following?
A chemical change in a substance.
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उत्तर
Chemical changes are changes that involve the reaction of substances with one another. Such reactions result in alterations in the chemical compositions of the substances involved. These changes lead to the formation of new substances.
Characteristics:
- One or more new substances are formed during a chemical change.
- Most chemical changes cannot be reversed easily.
- The chemical composition of a substance undergoing chemical change does not remain the same.
- A chemical change is always accompanied by a change in energy.
संबंधित प्रश्न
Classify the following as chemical or physical change:
Dissolving common salt in water.
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 |
Dissolving salt in water is a reversible change.
Classify the following as physical or chemical changes :
Breaking of a glass tumbler
Classify the following as a physical or a chemical change.
Burning of paper
State which of the following 1 to 5 pertain to – A: Physical Change B: Chemical change :
- Sublimation.
- Fermentation.
- Liquefaction or condensation.
- Magnetization.
- Respiration.
Give the reason why the following is considered as chemical changes.
A piece of magnesium strip is dropped into a beaker containing dilute hydrochloric acid.
Match the examples of changes in List I with the correct type of change in List II.
| List I | List II |
| 1. Burning of paper | A: Physical change |
| 2. The ringing of an electric bell | B: Chemical change |
| 3. Curdling of milk | |
| 4. Electric light is switched on | |
| 5. Melting of butter |
Wood to sawdust:______:: Wood to Ash: Chemical change
A physical change is generally____________.
