231. The sprue in wax pattern should be placed________________?

A. At right angle
B. At 45°C angle
C. At obtuse angle
D. It depend upon type of wax pattern

232. Gold content of an 18 carat alloy is______________?

A. 25%
B. 50%
C. 75%
D. 100%

233. Titanium casting is done_____________?

A. Under vacuum in argon atmosphere
B. Under air pressure in nitrogen atmosphere
C. In specially fabricated aluminium vanadium
D. Using CAD-CAM technique

234. Heat hardening is the process done at_______________?

A. Heating 750°C and slowly cooling to zero degree
B. Heating quickly upto 450°C followed by sudden quenching
C. Heating upto 250°C for 15 to 30 min
D. Heating at 750°C and then quenching to room temperature

235. Crucible indicated for casting base metal alloys is______________?

A. Carbon crucible
B. Clay crucible
C. Quartz crucible
D. High melting plastic crucible

236. Which of the following refractory is used to counteract most of the expansion________________?

A. Quartz
B. Cristobalite
C. Tridymite
D. Corundum

237. Passivating alloys are_______________?

A. Cr, Al, Ti
B. Cr, Mo, Ti
C. Cr, Gold, Ti
D. Cr, Fe, Ti

238. Waxes are used for_______________?

A. Primary impression
B. Corrective impressions
C. Impression of single tooth
D. None of the above

239. A common electrolyte used for plating copper indirect dies is_______________?

A. Copper cynide
B. Ionic copper
C. Acidic copper sulfate
D. Silver cyanide

240. Stainless steel is used mostly in dentistry_________________?

A. To strength amalgam
B. In orthodontic wires
C. To construct clasps for partial dentures
D. To replace internal gold restorations


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