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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:
Melting of butter in a pan
Classify the following as chemical or physical change:
Boiling of water to form steam.
Explain why burning of wood and cutting it into small piece are considered as two different types of changes.
Tick the most appropriate answer
2. Melting of ice is a
- reversible change
- irreversible change
- chemical change
- none of these
Fill in the blank.
A new substance is formed in a ............... change.
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 |
Chemical changes are accompanied by changes in energy.
Classify the following changes as physical or chemical:- melting of a solid (wax)
What do you observe when :
lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
Tick the most appropriate answer.
Rising and setting of the sun at a given place is a
Classify the following as a physical or a chemical change.
Burning of coal
State what is meant by the term – interconversion of matter. Is interconversion of matter a physical change or a chemical change.
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.
Name the following:
The final product of the physical change involved during the ‘melting of a piece of wax’.
Compare the energy changes involved during a physical and a chemical change.
Is a change of state of matter – a physical or a chemical change. Give reasons.
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
Select the chemical changes from the following list of changes
The crystallisation of salt from its solution.
Distinguish physical and chemical changes.
Tearing of sheet of paper into pieces is ______ By the process of Heating of water, change.
