MolSynapsequestion bank
MolSynapse / Question bank / s-Block Elements / Important compounds: NaOH, Na2CO3, NaHCO3, CaO, CaCO3, plaster of Paris
JEE Advanced levelOne or more correct optionsDifficulty 3 of 3sb216

Which of the following statements about plaster of Paris are correct?

  1. AIt contains one molecule of water of crystallisation per formula unit of .
  2. BOn mixing with water it sets to a hard mass of gypsum, with a slight expansion in volume.
  3. CIt is formed by heating gypsum to about 393 K.
  4. DHeating it above 473 K gives anhydrous that sets very slowly.

Answer: B, C, D

gives the hemihydrate near 393 K, which hydrates and recrystallises with a small expansion. Overheating gives dead burnt plaster. The hemihydrate has water per , not one.
Practice s-Block Elements More on Important compounds: NaOH, Na2CO3, NaHCO3, CaO, CaCO3, plaster of Paris
Previous questionNext question

More questions on Important compounds: NaOH, Na2CO3, NaHCO3, CaO, CaCO3, plaster of Paris