Q. In the hardening stage of plaster of Paris, the compound formed is
A) $CaSO_{4}$
B) Orthorhombic $CaSO_{4}\ .\ 2H_{2}O$
C) $CaSO_{4}\ .\ H_{2}O$
D) Monoclinic $CaSO_{4}\ .\ 2H_{2}O$
Explanation
(d)
Plaster of Paris absorb water to form monoclinic gypsum which is a hard substance.
$\ CaSO_{4}\ .\frac{1}{2}H_{2}O\ \overset{\ \ \ \ \ 3/2H_{2}O\ \ \ \ \ }{\rightarrow}\ CaSO_{4}\ .2H_{2}O$
monoclinic gypsum
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.