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प्रश्न
What is the difference between dissolution of sugar and burning of sugar ?
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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
Classify the following as chemical or physical change:
Melting of butter in a pan
Choose the most appropriate answer.
Rising and setting of the sun at a given place is a
Tick the most appropriate answer.
4. Chemical changes involve
- change in shape.
- change in size.
- change in molecular composition.
- none of these
Tick the most appropriate answer.
5. Photosynthesis requires
- heat energy.
- wind energy
- sunlight.
- sound energy
Write true or false for the statement.
Dissolving of solute in a solvent and rusting of iron are both physical changes.
Classify the following changes as physical or chemical: curdling of milk
What are man-made changes ?
Classify the following as physical or chemical change :
Growth of a plant
State which of the following pertain to – chemical changes.
- Substance retains its identity.
- The change is permanent.
- No new substance is formed.
- Is easily reversible.
- Produces one or more new substances by a change in its composition.
- The change is temporary.
- The composition and properties of the original substance are not altered.
Cutting a log of wood into pieces is a chemical change.
