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प्रश्न
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
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उत्तर
Heating a platinum wire, the final product is again platinum wire (as platinum is a noble metal and does not react with air), i.e. no change in composition and is a physical change. Heating magnesium wire forms MgO i.e. composition changes a new substance white powder of magnesium oxide is formed is a chemical change.
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संबंधित प्रश्न
Write true or false for the statement.
Burning of paper and formation of curd are reversible changes
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cutting wood into small pieces —
Solve this crossword by using the clues that follow-
Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
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Down
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3. It is a physical change.
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A change in which a substance retains its identity is a
______ change.
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Reason: A physical change is a reversible change.
A physical change is generally____________.
