Question: The product, which is obtained by calcining gypsum under steam pressure at 120-130°C or by dehydrating gypsum in the presence of sodium succinate is_______________?

• 1. Alpha – hemihydrates
• 2. Beta – hemihydrates
• 3. Calcium sulphate dihydrate
• 4. Orthorhombic anhydrate

Question: The strength of gypsum prouducts is generally expressed in terms of______________?

• 1. Tensile strength
• 2. Wet strength
• 3. Green strength
• 4. compressive strength

Question: The function of 2% potassium sulphate in a gypsum product is_____________?

• 1. To regulate the setting expansion
• 2. Regulate setting time
• 3. Acts as retarder
• 4. None

Question: Finer particle size of silica______________?

• 1. Slower the hygroscopic expansion
• 2. Greater the hygroscopic expansion
• 3. Normal setting expansion
• 4. No setting expansion

Question: ADA specification number of gypsum products are described under____________?

• 1. 1
• 2. 4
• 3. 12
• 4. 25

Question: Modiffiers are added to gypsum mainly to_______________?

• 1. Modify setting time
• 2. Modify setting expansion
• 3. Modify strength
• 4. Decrease the porosity

Question: Placing cast under tap water is to be avoided as______________?

• 1. H2O interferes with hygroscopic expansion
• 2. H2O inhibits polymerization of dental resin
• 3. H2O interferes with Crystallization of dihydrate
• 4. Gypsum is slightly soluble in water and the surface of the cast will be eroded

Question: The β (Beta) hemihydrate of gypsum requires more water to float its powder particles because______________?

• 1. They are more regular in shape and dense
• 2. They are more regular in shape and highly porous
• 3. They are more irregular in shape and porous
• 4. They are more dense and prismatic in shape

Question: In plaster of paris the setting time is primarily altered by_________________?

• 1. Altering P / L Ratio
• 2. Altering temperature of mixing water
• 3. Speed and length of hand spatulation
• 4. Addition of accelerators and retarders

Question: Which is gypsum product_______________?

• 1. Stone
• 2. Plaster
• 3. Investment
• 4. All of the above