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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
State whether the following is physical or chemical changes.
glowing of a bulb -
Fill in the blank
Heat is ________ by a gas during the process of condensation.
The rusting of an iron object is called :
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.
Name the following.
The product of the chemical change in keeping a polished iron nail exposed to the atmosphere.
Natural changes which take place in nature on their own, are beyond the control of human being.
______ is the Universal Solvent.
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If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think rust is different from iron?
Explain the characteristics of physical change with examples.
