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प्रश्न
Is a change of state of matter – a physical or a chemical change. Give reasons.
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उत्तर
- There are three different states of matter: solid, liquid, and gas. The transition between various states, such as solid to liquid (melting), liquid to gas (boiling), and vice versa (freezing and condensation), is referred to as a change of state.
- Take water (H2O) as an example. There are three states of water: As a solid (ice), a liquid (water), or a gas (steam).
- Water becomes ice (solid) when it freezes. Ice melts and returns to liquid form as water. Water transforms into steam (gas) when it boils. Steam condenses back into liquid water when it cools.
- The chemistry of water (H2O) remains unchanged during these modifications. The actual chemical identity of water remains unchanged; the molecules are merely rearranged.
- We categorize the change of state of matter as a physical change as the substance's chemical makeup does not alter throughout the transition. Even though a substance undergoes a physical change, its chemical identity is unaffected.
- The change of state of matter is a physical change because the chemical composition does not alter; it remains H2O in all states.
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संबंधित प्रश्न
Which of the following are chemical changes?
- Growth of a plant
- Rusting of iron
- Mixing of iron fillings and sand
- Cooking of food
- Digestion of food
- Freezing of water
- Burning of candle
Tick the most appropriate answer
2. Melting of ice is a
- reversible change
- irreversible change
- chemical change
- none of these
Tick (√) the correct alternative from the choice given for the following statement.
A substance which can not sublime is
Name two reversible changes.
Given reason:
Cutting of a cloth piece is a physical change, though it cannot be reversed.
Ice kept in a beaker, slowly melts and turns into water. The water in the beaker on solidification is freezing turns back to ice. Give four reasons why the change from ice to water and water back to ice is considered a physical change.
Ammonium chloride is also a sublimable solid. Give a reason why the sublimation of ammonium chloride involves a physical and a chemical change.
Name the following.
The gaseous product of the chemical change which takes place during respiration in living organisms.
Assertion: Burning of wood log to charcoal is a physical change.
Reason: The products formed of burning a piece of wood can be easily converted back to wood log.
Water is known as a universal solvent. Why?
