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WorksheetsGypsum Product II
Total questions: 20
Worksheet time: 10mins
Chemical formula for Gypsum is
CaSO4 .2H2 O
CaSO4 H2 O
CaSO4 .1/2H2 O
CaSO4
Gypsum product commonly used for making dies is
Type I
Type II
Type III
Type IV
Type lll gypsum product is known as
Die stone
Dental stone
Plaster of Paris
Impression plaster
Type 1 gypsum product is mainly used for
Making casts
Recording impressions
Making dies
Making models
The type of gypsum product manufactured by dry calcination is
Type V
Type IV
Type III
Type II
The gypsum product manufactured by heating gypsum under steam pressure to about 110-130°C in an autoclave is
Type I
Type II
Type III
Type IV
Setting reaction of gypsum products involves conversion of
Calcium sulphate hemihydrate to calcium sulphate dihydrate
Calcium sulphate dihydrate to calcium sulphate hemihydrate
Calcium sulphate hemihydrate to calcium sulphate anhydrite
Calcium sulphate dihydrate to calcium sulphate anhydrite
Working time of gypsum products can be increased by
Decreasing water:powder ratio
Using slurry water for mixing.
Addition of potassium sulphate
Addition of borax
The following gypsum product consists of β-calcium sulphate hemihydrate crystals
High strength, High expansion die stone
Dental plaster
Densite
Dental stone
The gypsum products with lowest and highest water:powder ratios are respectively
Type IV & type V
Type ll & type lll
Type V & type l
Type lll & type IV
What is the amount of heat released during setting of gypsum product ?
2500 cal
3100 cal
3900 cal
4300 cal
Water required to convert 100g of calcium sulphate hemihydrate to calcium sulphate dihydrate is
18.6 ml
22.2 ml
30.4 ml
45.3 ml
The hemihydrate crystals in dental stone are
Prismatic and spongy
Dense and prismatic
Dense and irregularly shaped
Spongy and irregularly shaped
Die is also known as
Impression of single tooth
Impression of Whole arch
Replica of single tooth
Replica of Whole arch
Balanced stone is Dental stone which
Has crystal of uniform size
Has controlled water of Hydration
Has Accelerators & Retarders according to need
Undergoes rapid Expansion
The main difference between dental stone and dental plaster is:
Chemical composition
Shape & Size of Particles
Shelf life
Solubility
Which of the following is true regarding plaster of paris
Has porous and irregular crystals
Has W:P ratio of 0.20
Produced by wet caicination
is α- Hemihydrate
Gypsum product with shortest setting time is
Die stone
Dental stone
Impression plaster
Dental plaster
Balanced gypsum products contain K2 SO4 and Borax in the ratio
1:1
10:1
100:1
1:10
Which of the following is the mosy widely accepted theory for setting of gypsum product ?
Dissolution : Precipitation theory
Hydration theory
Gelation theory
Acid base theory
