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प्रश्न
Boojho’s sister broke a white dove, a symbol of peace, made of Plaster of Paris (POP). Boojho tried to reconstruct the toy by making a powder of the broken pieces and then making a paste by mixing water. Will he be successful in his effort? Justify your answer.
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उत्तर
Boojho will not be successful because making of toy from Plaster of Paris (POP) is an irreversible change. Once the Plaster of Paris is mixed with water and dried it cannot regain its properties.
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संबंधित प्रश्न
Short Answer Type Question:
What is a physical change? Explain with example.
When a candle is lit the following changes are observed.
- Wax melts.
- Candle keeps burning.
- The size of the candle decreases.
- The molten wax solidifies
- Which of the changes can be reversed? Justify your answer
Evaporation of water is a reversible change.
Rusting of iron is a reversible change.
Name the two types of changes.
Look at the figure which shows three situations.
Which of these shows a reversible change and why?
A piece of iron is heated till it becomes red-hot. it then becomes soft and is beaten to a desired shape. What kind of changes are observed in this process-reversible or irreversible?
Can we reverse the following change? If yes, suggest the name of the method.
Ice into water
Which of the following changes cannot be reversed?
- Blowing of a balloon
- Folding paper to make a toy aeroplane
- Rolling a ball of dough to make roti
- Baking cake in an oven
- Drying a wet cloth
- Making biogas from cow dung
- Burning of a candle
Give one example of change which occurs on heating but cannot be reversed.
