The main difference between dental stone and dental plaster is______________? A. Chemical composition B. Self lifeC. Sharpe and size of particles D. Solubility in water

Gypsum is used for________________? A. Impressions B. Casts C. DieD. Casts and Dies

The strength of the gypsum specimen when the water in excess of that required for the hydrate of the hemihydrate is left in the specimen is called____________? A. Dry strengthB. Green strength C. Water strength D. Compressive strength

Balanced stone is dental stone_______________? A. Which undergoes rapid expansionB. In which accelerators or retarders have been added according to need C. In which amount of water of hydration is controlled D. In which the crystals are all of uniform…

Impression plaster containing potato starch is called______________? A. Plaster of parisB. Soluble plaster C. Anti – expansion solution D. Die stones

Powders of dental plaster and dental stone differ mainly in____________? A. Solubility B. Shelf life C. Chemical formulaD. Particle porosity

Beta hemihydrate particles absorb______________? A. More water B. Less water C. no water D. None of the above

Type III Dental gypsum is__________________? A. Class II stone B. DensiteC. Class I stone or hydrocal D. Model or lab plaster

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_______________? A. Alpha – hemihydrates B. Beta – hemihydrates C. Calcium sulphate dihydrate D. Orthorhombic anhydrate

The strength of gypsum prouducts is generally expressed in terms of______________? A. Tensile strength B. Wet strength C. Green strengthD. compressive strength