Gypsum – MCQ
1. Gypsum loses all its water of crystallization at about
a) 50° C.
b) 100° C.
c) 200° C.
d) 300° C.
View Answer
b) 100° C.
Gypsum loses all its water of crystallization at about 200° C.
2. Plaster of paris contains about
a) 4 % of water.
b) 6 % of water.
c) 8 % of water.
d) 10 % of water.
View Answer
b) 6 % of water.
Plaster of paris contains about 6 % of water.
3. Gypsum has
a) Low creep.
b) High bulk density.
c) Negligible shrinkage.
d) Dam proofing properties.
View Answer
c) Negligible shrinkage.
Gypsum has negligible shrinkage.
4. Keene’s cement is made from
a) Slag.
b) Gypsum.
c) Lime.
d) Puzzolana.
View Answer
b) Gypsum.
Keene’s cement is made from Gypsum.
5. Mack’s cement is made from
a) Slag.
b) Gypsum.
c) Lime.
d) Puzzolana.
View Answer
b) Gypsum.
Mack’s cement is made from Gypsum.
6. The number of water molecules present in gypsum is
a) 1/2
b) 1
c) 2
d) 3
View Answer
c) 2.
Gypsum – CaSO4. 2 H2O
Hence, the number of water molecules present in gypsum is 2.
7. The number of water molecules present in Plaster of Paris is
a) 1/2
b) 1
c) 2
d) None of these
View Answer
a) 1/2.
Palaster of Paris – CaSO4. 0.5 H2O.
Hence, the number of water molecules present in palaster of paris is 1/2 or 0.5.
8. The difference in the number of water molecules in gypsum and plaster of paris is
a) 1/2
b) 1/3
c) 2/3
d) 3/4
View Answer
c) 2/3.
Gypsum – CaSO4. 2 H2O. [ Number of water molecules is = 2]
Plaster of Paris – CaSO4. 0.5 H2O. [ Number of water molecules is = 0.5 0r 1/2]
So, the difference in number of water molecules in Gypsum and Plaster of Paris is = (2 – 1/2 ) = 1.5 0r 2/3.
9. The setting time of the plaster of paris is delayed by adding retardant
a) Clay.
b) Glue.
c) Cattle hair.
d) All of these.
View Answer
b) Glue.
10. In metallurgical industries the moulds are manufactured from gypsum of variety having
a) α-modification.
b) β-modification.
c) hygroscopicity.
d) Porus structure.
View Answer
a) α-modification.
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