391. The main difference between dental stone and dental plaster is______________?

A. Chemical composition
B. Self life
C. Sharpe and size of particles
D. Solubility in water

392. Gypsum is used for________________?

A. Impressions
B. Casts
C. Die
D. Casts and Dies

393. 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 strength
B. Green strength
C. Water strength
D. Compressive strength

394. Balanced stone is dental stone_______________?

A. Which undergoes rapid expansion
B. 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 size

395. Impression plaster containing potato starch is called______________?

A. Plaster of paris
B. Soluble plaster
C. Anti – expansion solution
D. Die stones

396. Powders of dental plaster and dental stone differ mainly in____________?

A. Solubility
B. Shelf life
C. Chemical formula
D. Particle porosity

397. Setting of POP is result of______________?

A. Difference in solubility of CaSo4 ½ H2O + CaSO4+ 2H2O
B. Reaction between CaSO4+ 2H2O and water
C. Nucleation and growth of CaSo4 ½ H2O crystals
D. Reaction between hemihydrate and hihydrate

398. Type I gypsum product is also called_______________?

A. Impression plaster
B. Class I stone / Hydrocal
C. Class II stone/Densite
D. Model plaster

399. Plaster of paris _____________?

A. Is wet calcined hemihydrate
B. Has porous and irregular crystals
C. Is a – hamihydrate
D. Has a W / P of 0.2

400. As per DNA No. 25, minimum amount of setting expansion required for type V gypsum products_______________?

A. 0.05
B. 0.10
C. 0.15
D. 0.20


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