Correct Answer – A

Correct Answer – A
Plaster of Paris is prepared by heating gypsum at `120^(@)C`.
`underset(“Gypsum”)(2CaSO_(4).2H_(2)O)rarr underset(“Plaster of Paris”)((CaSO_(4))_(2).(1)/(2)H_(2)O)+3H_(2)O`
On heating plaster of Paris at `200^(@)C`, if forms anhydrous calcium sulphate i.e., dead plaster which has no setting property as at absorbs water very slowly.
`CaSO_(4).(1)/(2)H_(2)O overset(200^(@)C)rarr underset(“Anhydride”)(CaSO_(4)) overset(1100^(@)C)rarr CaO +SO_(3)`

Correct Answer – A

Correct Answer – A
`CaSO_(4)` is dead burnt cement.