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Q.
Dead burnt plaster is
The s-Block Elements
Solution:
$2(CaSO_4.2H_2O) \xrightarrow{393\, K }$
$2(CaSO_{4}.\frac{1}{2} H_2O + 3H_2O \xrightarrow{> 393\,K} CaSO_4 $
Anhydrous $CaSO_4$ is known as dead burnt plaster