251. Tublulence of molten gold is due to _____________?

A. Impurities in gold
B. Improper venting
C. A and B
D. None of the above

252. In a patient with allergy to costume jewelry, which of the following is contraindicated______________?

A. High gold
B. Low gold
C. Palladium – Ag
D. Ni – Cr

253. Indium in metal alloys_______________?

A. Improve bonding
B. Harden the metal ceramic Ag-Pd alloy
C. Both A and B
D. None of the above

254. Mouth temperature waxes are_______________?

A. Iowa wax
B. Modeling wax
C. Green stick wax
D. None of the above

255. Incomplete casting is the result of_____________?

A. More porous investment in the mould
B. Narrow sprue diameter
C. Hollow sprue pin
D. Large reservoir

256. Glossy smooth margins of a casting are due to_____________?

A. Shrinkage of alloy on cooling
B. Investment breakdown
C. Incomplete wax elimination
D. Incomplete gas elimination

257. Gypsum bonded investment should not be heated over______________?

A. 700°C
B. 1,300°C
C. 1,063°C
D. 900°C

258. Cobalt-Chrominum alloys contains_______________?

A. 30% cobalt and 60% chrominum
B. 60% cobalt and 30% chrominum
C. 1% palladium
D. 20% gold

259. The most commonly used Titanium alloy for dental and medical purposes is________________?

A. Ti 6Al 4V
B. Ti 5Al 4V
C. Ti 5Al 5V
D. Ti 6Al 6V

260. Wax pattern is ideally invested immediately to decrease the dimensional changes caused by_______________?

A. Decrease flow
B. Continuous expansion
C. Relaxation of the internal stresses
D. Water loss


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