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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
Classify the following as chemical or physical change:
Rusting of almirah
Fill in the blank.
An earthquake is a .................. change.
State whether the following is physical or chemical changes.
water cycle in nature —
State whether the following is physical or chemical changes.
shaping a piece of glass —
Write true or false
Cutting of paper into pieces is a chemical change.
Tick (√) the correct alternative from the choice given for the following statement
A pop sound is heard when a lighted match stick is brought near the mouth of a jar. This indicates the release of gas.
A physical change is temporary. Explain.
Classify the following as a physical or a chemical change.
Melting of wax
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.
Desirable and undesirable 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
State which of the following terms connected with change of state of matter i.e.
(a) Melting
(b) Vaporisation
(c) Condensation
(d) Freezing
pertain to –
- Conversion of a liquid into a vapour or gas.
- Conversion of a liquid into a solid.
- Conversion of a solid into a liquid on heating.
Select the chemical changes from the following list of changes
The crystallisation of salt from its solution.
Select the chemical changes from the following list of changes
Change of seasons
Select the correct answer from the choice given below to complete the sentence
The energy required for completion of a physical change is ______________ when the change is reversed.
When ice melts to form water, change occurs in its
Tearing of sheet of paper into pieces is ______ By the process of Heating of water, change.
Give two examples for the following case:
Physical changes which are reversible
Give two examples for the following case:
Physical changes which are not reversible
Mention a few physical properties of a substance.
