261. The maximum carbon content of steel used in dentistry is__________________?

A. 19%
B. 2%
C. 1.7%
D. 4%

262. Flux is used during casting to________________?

A. Remove the oxides formed on the gold alloy
B. Lower the melting point
C. Replace casting wax
D. Speed the burnout process

263. Resistance to corrosion in a cobalt-chrome casting is due to presence of_______________?

A. High quality iron
B. Chrome
C. Cobalt
D. Nickel

264. Which is the use of boxing an impression______________?

A. Ease of construction of denture
B. Preserving the sulci
C. Ease of pouring an impression
D. All of the above

265. Gap between true end of casting ring and wax pattern should be______________?

A. ¼ inch
B. ½ inch
C. 3/8 inch
D. one inch

266. Addition of large amounts of platinum to a casting gold alloy will________________?

A. Decrease its strength and ability to be hardened
B. Decrease its tarnish resistance
C. Increase its fusion temperature
D. Redden the alloy

267. All of the following statements about cast cobalt alloy are true EXCEPT_____________?

A. They have a modulus of elasticity twice that of gold alloys
B. They are more rigid than gold alloys
C. They have higher ductility than gold alloys
D. They have a lower proportional limit than gold alloys

268. 4th state of matter is______________?

A. Solid
B. Liquid
C. Gas
D. Colloid

269. All of the following statements about an alginate impression are EXCEPT________________?

A. It should be rapidly displaced from the mouth
B. It may exhibit fluid exudates on the surface as a result of imbibition of water
C. It will take up water and expand if kept wet
D. It will shrink as a result of syneresis

270. Type I and Type II zinc oxide impression paste differ with respect to_______________?

A. Their use
B. Their hardness after setting
C. Water content
D. Eugenol content