1. the strength of gypsum bonded investment is dependednt uponcopper contentsilica contentcarbon contentgypsum contentQuestion 1 of 20 2. Fluoride flux used in soldering works by Preventing flow of solder to other areasPrevents formation of chromium oxide or dissolves already formed chromium oxideForms a protective film during solderingWeakens the solder jointQuestion 2 of 20 3. Which of the following statements is not true regarding creep?creep gradually increases the marginal integrity of an amalgam restorationundertrituration tends to increase the creep rateincreasing the condensation pressure decreases the creep ratecreep is a process that happens over timeQuestion 3 of 20 4. Most common accelerator used in gypsum is:Sodium Chloride1 % potassium sulphate2% potassium sulphate2% sodium sulphateQuestion 4 of 20 5. Fins and spines in casting are caused by:Increased casting pressureProlonged heatingWater film presentRapid heating of investmentQuestion 5 of 20 6. heat energy required for vaporisation of liquid after boilingmelting temperaturelatent heat of sublimationlatent heat of vaporisationlatent heat of fusionQuestion 6 of 20 7. exposure of a stone cast to tap water should be minimised becausethe cast will be weakeneddimensional achange will occur in th ecasteroding of the cast will resultthe surface of the cast will acquire a chalky appearanceQuestion 7 of 20 8. The process in which a solid melts into a liquid with a separate crystalline phase is known as:Congruent MeltingSinteringCerammingIncongruent meltingQuestion 8 of 20 9. Wettability can be increased by:Reducing the internal stressesIncrease in surface energyIncreasing the contact angleIncrease in surface areaQuestion 9 of 20 10. In mixing dental stone, why should the powder be sprinkled onto the water in the bowl?the addition of powder prevents the mix from becoming exothermicthe powder is added to the water to avoid using more than one bowlthis is not recommended; the water should be added to the powderthis process results in better powder mixing and reduced chance for air bubblesQuestion 10 of 20 11. Non eugenol pastes contain ____ instead of eugenol:Zinc chlorideZinc acetateOrthoethoxy benzoic acidPolyethylmethacrylateQuestion 11 of 20 12. oxides of all of the following elements in noble metal alloys help in bonding to porcelain excepttinindiumironnickelQuestion 12 of 20 13. a thinner mix of gypsum bondeded investment will result indecrease setting expansionincreases setting expansionproduce a smoother castingincreases thermal expansionQuestion 13 of 20 14. Pyroplastic flow in dental porcelainShould optimally be highIs decreased with a low soda/potash ratioIs not an important considerationIs determined by potash formQuestion 14 of 20 15. bonding of GIC to tooth structure is brought about byfine pumicemetal ionscarboxyl grouphydroxyl groupQuestion 15 of 20 16. porcelain are made opaque by the addition of oxides ofboron and magnesiumtitanium and tiniron and aluminiumnickel and iridiumQuestion 16 of 20 17. nickel in high percentages in noble metal dental casting alloysall of the abovedecreases strengthincreases ductilitydecreases tarnish resistanceQuestion 17 of 20 18. the effectiveness of condensation and prevention of porcelain shrinkage is determined byuse of powder containing particles that are of same sizethickness of platinum mixspeed of icrease of furnace heatshape and size of particlesQuestion 18 of 20 19. Stress is:Force applied perpendicular to the surfaceA deformation resulting from an applied loadAn internal force opposing an applied loadForce applied per unit areaQuestion 19 of 20 20. the main advantage of a natural glaze rather than an applied glaze is that the natural glazeis more permanentoffers best estheticsis easier to achieverequires a lower firing temperatureQuestion 20 of 20 Loading...
