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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
Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
Melting of solid (wax) is a physical change.
Write short answer.
Sublimation is classified as a physical change. Why ?
Classify the following changes as physical or chemical:-boiling
Write true or false
Burning of sugar is a temporary change.
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 |
Give reasons why – separation of mixtures e.g. iron from a mixture of iron and sulphur is a physical change, but heating a mixture of iron and sulphur is considered a chemical change.
Select the chemical changes from the following list of changes
Butter turning rancid
Stretching gold coin into a ring is a ______ change.
Give an example to justify the statement that physical changes can be reversible as well as irreversible.
