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प्रश्न
What is the difference between dissolution of sugar and burning of sugar ?
उत्तर
1. Dissolution of sugar:
- When sugar is dissolved in water it disappears. It we taste the solution, the sugar is still present in dissolved form.
- If water is evaporated we get back the sugar.
- So it is a physical and reversible change.
2. Burning of sugar:
- Fire activates a chemical reaction between sugar and oxygen. The oxygen in the air reacts with the sugar as the chemical bonds broke.
- Energy is released in the form of smoke.
- So, burning a sugar is a chemical change.
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संबंधित प्रश्न
Tick the most appropriate answer
2. Melting of ice is a
- reversible change
- irreversible change
- chemical change
- none of these
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 |
Write true or false for the statement
A natural change can also be a desirable change
Melting of solid (wax) is a physical change.
Write short answer.
Name two reversible changes.
State whether the following is physical or chemical changes.
cutting wood into small pieces —
Tick (√) the correct alternative from the choice given for the following statement.
An example of both physical and chemical change is
Tick the most appropriate answer.
Physical changes are
Match the examples of changes in List I with the correct type of change in List II.
| List I | List II |
| 1. Burning of paper | A: Physical change |
| 2. The ringing of an electric bell | B: Chemical change |
| 3. Curdling of milk | |
| 4. Electric light is switched on | |
| 5. Melting of butter |
In a solution of salt in water, water is the solute
