Why should plaster of Paris be used quickly after mixing with water?
Answer and explanation
Correct answer: It quickly takes up water and forms a hard gypsum-like substance
The governing concept is the setting reaction of plaster of Paris. Calcium sulphate hemihydrate, CaSO₄·½H₂O, combines with water and changes into hard gypsum, CaSO₄·2H₂O. Because this hydration and setting begin soon after mixing, the paste must be shaped and applied promptly. Option A is correct; it does not escape as a gas, acidify water, or become a metal.
Frequently asked questions
What is the correct answer to this question?
It quickly takes up water and forms a hard gypsum-like substance
Why is this the correct answer?
The governing concept is the setting reaction of plaster of Paris. Calcium sulphate hemihydrate, CaSO₄·½H₂O, combines with water and changes into hard gypsum, CaSO₄·2H₂O. Because this hydration and setting begin soon after mixing, the paste must be shaped and applied promptly. Option A is correct; it does not escape as a gas, acidify water, or become a metal.
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.
