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प्रश्न
Define a chemical change. Give two examples of the above changes.
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उत्तर
A permanent change in which new substances are formed whose composition and properties are completely different from those of the original
substances.
Chemical change:
(i) Burning of wood.
(ii) Breathing.
संबंधित प्रश्न
Tick the most appropriate answer.
5. Photosynthesis requires
- heat energy.
- wind energy
- sunlight.
- sound energy
Fill in the blank.
An earthquake is a .................. change.
Ripening of fruits is a desirable change.
Chemical changes are accompanied by changes in energy.
How do you say that the process of digestion is a chemical change ?
Classify the following changes as physical or chemical:-boiling
Is burning a physical change or a chemical change? Why?
Tick (√) the correct alternative from the choice given for the following statement.
A substance which can not sublime is
State the Differences Between a Physical Change and a Chemical Change.
Classify the following as physical or chemical changes :
- Cooking of food
- Boiling of water
- Cutting of trees
- D0issolving salt in water
- Digestion of food
- Melting of ice
Fill in the blank.
A change, which alters the composition of a substances, is known as a___________ change.
Given reason:
Freezing of water to ice and evaporation of water are physical changes.
Given reason:
Cutting of a cloth piece is a physical change, though it cannot be reversed.
Distinguish between the following.
Physical change and chemical change
Change is the law of nature and occurs in our everyday life, at all times and in all places.
Differentiate between the following change with a suitable example.
Periodic and non-periodic change
Explain the term – ‘sublimation’. Is sublimation of naphthalene – a physical or a chemical change. Give reasons.
Fill in the blanks with the appropriate words of the statement given below:
Heating a piece of iron is considered a __________ change while heating a piece of coal [carbon] is considered a ___________ change.
Compare the energy changes involved during a physical and a chemical change.
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
______ is the Universal Solvent.
