Question

The difference of water molecules in gypsum and plaster of paris is :

• A. $\frac{5}{2}$
• B. $2$
• C. $\frac{1}{2}$
• D. $1\frac{1}{2}$

Answer 1

Answer: (D)

$1\frac{1}{2}$

Gypsum: $CaS{O}_4.2H_{2}O$

Plaster of paris: $CaS{O}_4.1/2H_{2}O$

So, difference between water molecules

$=2-\frac{1}{2}=1\frac{1}{2}$