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प्रश्न
Which of the following are chemical changes ?
- decaying of wood
- burning of wood
- sawing of wood
- hammering of nail into wood
पर्याय
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)
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उत्तर
(i) and (ii)
The processes in statements (i) and (ii) are chemical changes because decaying and burning causes formation of new compounds; thus they are chemical reactions. The processes in statements (iii) and (iv) are physical changes where no new compounds are formed.
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संबंधित प्रश्न
State whether the following is physical or chemical changes.
lightning —
State whether the following is physical or chemical changes.
(energy produced) dissolving sugar in water —
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
Classify the following as a physical or a chemical change.
Boiling of water
Classify the following as a physical or a chemical change.
Melting of wax
Potassium chloride is added to water and stirred. A salt solution is obtained, which is then boiled, leaving behind a residue.
- Is the above change physical or chemical?
- Name the residue which remains behind after the salt solution is boiled.
- Is the change reversible or not reversible?
- Are the composition and properties of the original substance altered?
- Give a reason why the above experimentation would not be possible if calcium carbonate was taken in place of potassium chloride.
Select the chemical changes from the following list of changes
Vaporisation of water into water vapour.
Select the chemical changes from the following list of changes
Respiration in mammals.
When solute is dissolved in a solvent it forms a solution.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think rust is different from iron?
