221. Which of the following is function of fluoride flux in soldering process ?

A. It prevents the formation of copper oxide
B. It prevents the formation of chromium oxide or dissolves chromic oxide layer
C. It prevents the flow of material in undesirable area
D. Increase the strength of solder

222. Percentage of gold in high noble alloy is______________?

A. N 25%
B. 25%
C. >40%
D. 0%

223. Gases dissolved in molten metals are liberated when cooled giving rise to________________?

A. Suckback porosity
B. Gas inclusion porosity
C. Localized shrinkage porosity
D. Microporosity

224. Casting flux is used to_______________?

A. Prevent the oxidation of the metal during melting
B. increase the melting point of the flux
C. Flaring the point of the sprue attachment
D. None of the above

225. The main ingredient of inlay wax is__________________?

A. Candellila wax
B. Paraffin wax
C. Carnauba wax
D. Gum dammar

226. Who was the first person to introduce cast inlay restoration into dentistry ?

A. William H Taggart
B. Buonocore
C. G.V. Black
D. Bowen

227. Disadvantage of having a short sprue is________________?

A. Rapid solidification of metal
B. No place for reservoirs
C. Incomplete evacuation of gases
D. Difficulty in removing casting from investment

228. 18-B Stainless steel orthodontic wire has_______________?

A. 18% Nickel 8% Chrominum
B. 18% Chromium 8% Nickel
C. 18% Chromium 8% Cobalt
D. 18% Carbon 8% Iron

229. Inlay wax is used to_______________?

A. Temporarily cement inlays:
B. Make inlay wax patterns
C. Invest inlay patterns
D. Box models

230. Quartz in investment material is added for_______________?

A. Strength
B. Expansion components for casting shrinkage
C. Decrease strength
D. Contraction

 

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