941. The best gas for melting an alloy is?
A. natural gas
B.hydrogen
C.acetylene
D.helium
E.Propane

942. Which of the alloying elements decreases the hardness of steel?
A. Nickel
B. Cobal
C.Manganese
D.Carbon

943. Silver added to a solder, does not perform which role?
A. Narrows the melting range
B.Increases flow of the solder
C.Acts as a deoxidizer
D.Increases adherence of solder to metal
E.None of the above

944. Which of the following is not a type of copolymer?
A. Block
B.Chain transfer
C.Graft
D.Random
E.All of the above are copolymer types

945. Fluxes for soldering base metal alloys contain all of the following, except
A.sodium pyroborate
B.mica
C.boric acid
D.silica

946. The average processing shrinkage of a self-curing resin denture is?
A.4.5%
B.0.01%
C.0.006%
D. 0.25%

947. The principal difference between heat-cured denture base resins and cold-cured resins is the?
A. absence of initiator in cold-cured resins
B. presence of amine activator in cold-cured resins
C.absence of dibutyl phthalate plasticizer in cold-cured resins
D.absence of initiator in heat-cured resins
E.basic structure of the resins

948. Which of the following non-aqueous elastomeric Impression materials has the least shelf-life?
A. Condensation
B.Polysullides
C.Polyethers
D.Addition silicones

949. Vitallium is an alloy of?
A. chromium and cobalt
B. nickel and chromium
C.iron, nickel and chromium
D.nickel and titanium

950. When curing visible light curing resins, the light must be held?
A.close to but not touching the restoration
B.1 cm away from the restoration
C. as far away as possible from the restoration
D. touching the restoration