Gypsum Product II

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