901. What should be the optimum thickness of rubber base impression materials in a tray ?
A.At least 10mm
D. Less than 1mm

902. The liquid for heat-cured acrylic resins contains all of the following, except ?
A. hydroquinone
B.methyl methacrylate
C.glycol dimethacrylate
D. dimethyl-p-toluidine
E.dibutyl phthalate

903. In which stage is the heat-curing resin material packed into the mold?
A. Adhesive stage
B.Rubbery stage
C.Tacky stage
D. Stringy stage
E.Doughy stage

904. Which of the following is the first sign of preset hydration in a gypsum product?
A. Prolonged setting time
B.Decreased strength
C.Increased thermal expansion
D.Increased hygroscopic expansion
E. accelerated setting

905. The setting of dental plaster can be accelerated by?
A. mixing with boiling water
B.increasing the water to powder ratio
C.the addition of borax
D. rapid vigorous mixing
E. all of the above

906. When testing the biocompatibility of dental materials for evaluation of pulp reactions, the material which is used as negative control is?
A.gold filling
B.calcium hydroxide cement
C. zinc oxide eugenol cement
D. amalgam filling
E. silicate cement

907. The modulus of elasticity or Young’s modulus of a materials is indicative of its?
A. rigidity
C.impact force
D.breaking strength

908. When mixing plaster, the higher the W/P ratio the
A. weaker will be the gypsum product
B.longer will be the setting time
C.lesser will be the setting expension
D.all of the above
E.none of the above

909. A silver electroplating heat solution, will contain all of the following, except?
A. silver cyanide
B. potassium carbonate
C. distilled water
D. potassium cyanide
E. sulfuric acid

910. In a casting,subsurface porosity can be diminished by controlling the?
A. mold temperature
B.sprue length
C.melt temperature
D.rate at which the molten metal enters the mold
E.none of the above

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