Plaster of Paris is prepared by controlled heating of which substance?
Answer and explanation
Correct answer: Gypsum
Gypsum is calcium sulphate dihydrate, CaSO₄·2H₂O. Controlled heating removes part of its water of crystallisation and forms calcium sulphate hemihydrate, CaSO₄·½H₂O, known as plaster of Paris: CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O. Thus option A is correct; the other substances do not undergo this preparation reaction.
Frequently asked questions
What is the correct answer to this question?
Gypsum
Why is this the correct answer?
Gypsum is calcium sulphate dihydrate, CaSO₄·2H₂O. Controlled heating removes part of its water of crystallisation and forms calcium sulphate hemihydrate, CaSO₄·½H₂O, known as plaster of Paris: CaSO₄·2H₂O → CaSO₄·½H₂O + 1½H₂O. Thus option A is correct; the other substances do not undergo this preparation reaction.
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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