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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
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Cutting a log of wood into pieces is a chemical change.
Tick the most appropriate answer.
4. Chemical changes involve
- change in shape.
- change in size.
- change in molecular composition.
- none of these
State whether the following is physical or chemical changes.
respiration in living beings —
Tick the most appropriate answer.
Photosynthesis requires
Fill in the blank.
The process of a liquid changing into a solid is called ________
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
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?
Water is the universal solvent. Why?
Grinding of wheat grain changes its size. It is a ____________ change.
