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प्रश्न
State why addition of sodium chloride to water is considered a physical change, while addition of dilute sulphuric acid to zinc is considered a chemical change.
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उत्तर
Addition of sodium chloride to water is considered a physical change because it does not form any new substance. but when the addition of dilute sulphuric acid is added to zinc. They forms zinc-sulphate hence it is considered as a chemical change.
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संबंधित प्रश्न
Classify the following changes as physical or chemical: curdling of milk
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
Fill in the blank with the correct word of the statement given below:
Sublimation involves a __________ 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.
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
The carbon cycle.
Name the following.
The salt obtained when a chemical change takes place on the addition of iron to dilute sulphuric acid.
Match the following
| Sr. No. | A | B | C |
| 1. | Melting | Change of state from liquid to solid | Ticking of clock |
| 2. | Condensation | Change of state from liquid to gas | Formation of ice cube |
| 3. | Evaporation | Change of state from solid to liquid | Collecting flowers |
| 4. | Freezing | Change of state from gas to liquid | Ice cube to water |
| 5. | Periodic change | Occurs at irregular time intervals | Water to steam |
| 6. | Non-periodic change | Occurs at regular time intervals | Steam to water drops |
Water is the universal solvent. Why?
Mention some of the different conditions needed for chemical changes to occur.
