Why is plaster of Paris stored in a closed container away from moisture?
Answer and explanation
Correct answer: It can absorb water and change into gypsum
Plaster of Paris is calcium sulfate hemihydrate, CaSO4·1/2H2O. It reacts with water or atmospheric moisture and changes into gypsum, CaSO4·2H2O. This hydration causes the material to set and become hard, so it may lose its usefulness during storage. The other choices describe no relevant property: it neither forms a metal from oxygen, turns black in ordinary light, nor explodes with nitrogen.
Frequently asked questions
What is the correct answer to this question?
It can absorb water and change into gypsum
Why is this the correct answer?
Plaster of Paris is calcium sulfate hemihydrate, CaSO4·1/2H2O. It reacts with water or atmospheric moisture and changes into gypsum, CaSO4·2H2O. This hydration causes the material to set and become hard, so it may lose its usefulness during storage. The other choices describe no relevant property: it neither forms a metal from oxygen, turns black in ordinary light, nor explodes with nitrogen.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
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