Question

plaster of paris should be kept in moisture proof container. why?

Answer 1

Answer: The Plaster of Paris should be stored in a moisture-proof container as it absorbs water from moisture and turn into hard substance (Gypsum) as shown in following chemical equation.

$Equation \\ \\CaSo4. \frac{1}{2} H2O + H2O = > CaSo4.2H2O \\ \: \: \: \: \: Plaster \: of \: paris \: \: \: \: \: \: \: \: Gypsum$

Answer 2

It is bcoz as we know it absorbs moisture to form solid or hard substances called gypsum which can mainly makes Plaster of Paris useless.