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NDA 2019 GAT · General Knowledge · Chemistry in Everyday Life · medium

Plaster of Paris has the formula CaSO4.1/2 H2O. 2. It is obtained by heating gypsum at about 373 K.

Single correct option

Consider the following statements:
1. Plaster of Paris has the formula CaSO4.1/2 H2O.
2. It is obtained by heating gypsum at about 373 K.
Which of the statements given above is/are correct?
  1. A. 1 only
  2. B. 2 only
  3. C. Both 1 and 2
  4. D. Neither 1 nor 2
Show answer and solution

Answer: (C) Both 1 and 2

Gypsum, CaSO4.2H2O, loses three-quarters of its water of crystallisation on heating to about 373 K and becomes the hemihydrate CaSO4.1/2 H2O, called Plaster of Paris. Both statements are therefore correct. It sets to hard gypsum on mixing with water.
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Original question written in the NDA 2019 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake