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प्रश्न
Dead burnt plaster is ______.
पर्याय
CaSO4
\[\ce{CaSO4 . 1/2 H2O}\]
CaSO4.H2O
CaSO4.2H2O
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उत्तर
Dead burnt plaster is CaSO4.
Explanation:
Plaster of Paris is prepared by heating gypsum at 120°C
\[\ce{\underset{Gypsum}{2CaSO4 . 2H2O} -> (\underset{Plaster of Paris}{CaSO4)2 . H2}O + 3H2O}\]
On heating plaster of Paris at 200°C, it forms anhydrous calcium sulphate, i.e., dead plaster which has no setting property as it absorbs water very slowly.
\[\ce{CaSO4 . 1/2 H2O ->[200°C] \underset{Anhydride}{CaSO4} ->[1100°C] CaO + SO3}\]
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संबंधित प्रश्न
Describe two important uses of the following quicklime.
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Describe the importance of the plaster of paris.
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Match the elements given in Column I with the properties mentioned in Column II.
| Column I | Column II |
| (i) Li | (a) Insoluble sulphate |
| (ii) Na | (b) Strongest monoacidic base |
| (iii) Ca | (c) Most negative EΘ value among alkali metals. |
| (iv) Ba | (d) Insoluble oxalate |
| (e) 6s2 outer electronic configuration |
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\[\ce{Y <-[\Delta, 205°C] CaSO4.2H2O ->[\Delta, 120°C] X}\]
X and Y are respectively:
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