401. Beta hemihydrate particles absorb______________?
A. More water
B. Less water
C. no water
D. None of the above
402. Type III Dental gypsum is__________________?
A. Class II stone
C. Class I stone or hydrocal
D. Model or lab plaster
403. 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
404. The strength of gypsum prouducts is generally expressed in terms of______________?
A. Tensile strength
B. Wet strength
C. Green strength
D. compressive strength
405. The function of 2% potassium sulphate in a gypsum product is_____________?
A. To regulate the setting expansion
B. Regulate setting time
C. Acts as retarder
406. Finer particle size of silica______________?
A. Slower the hygroscopic expansion
B. Greater the hygroscopic expansion
C. Normal setting expansion
D. No setting expansion
407. ADA specification number of gypsum products are described under____________?
408. Modiffiers are added to gypsum mainly to_______________?
A. Modify setting time
B. Modify setting expansion
C. Modify strength
D. Decrease the porosity
409. Placing cast under tap water is to be avoided as______________?
A. H2O interferes with hygroscopic expansion
B. H2O inhibits polymerization of dental resin
C. H2O interferes with Crystallization of dihydrate
D. Gypsum is slightly soluble in water and the surface of the cast will be eroded
410. The β (Beta) hemihydrate of gypsum requires more water to float its powder particles because______________?
A. They are more regular in shape and dense
B. They are more regular in shape and highly porous
C. They are more irregular in shape and porous
D. They are more dense and prismatic in shape