621. Increase in the residual mercury in silver amalgam filling can_____________?

A. Cause fracture of the filling
B. Tarnish and corrosion
C. Increase the strength
D. Decrease condensation pressure

622. Which of the following statements about high copper silver alloy compared to conventional alloy is not true ?

A. It has increased tensile and compressive strength
B. It has poor tarnish and corrosion resistance
C. It’s edge strength is greater
D. Mercury content in the final restoration is less

623. Compare to conventional amalgams, spherical amalgams_______________?

A. Require more mercury
B. Require heavy compection forces
C. Have longer setting times
D. None of the above

624. Which of the following phases of dental amalgam has minimum strength____________?

A. Gamma 1
B. Gamma 2
C. Epsilon 1
D. Gamma 3

625. The ADA specification No 1 for composition of amalgam alloy recommends______________?

A. 65% silver, 32% tin and 3% copper
B. 49% silver, 32% tin and 19% cooper
C. 65% silver, 29% tin and 5-6% copper
D. None of the above

626. The highest mercury concentration in amalgam filling is found_____________?

A. At the margin of the restoration
B. In the centre of the restoration
C. In the deepest part of the restoration
D. None of the above

627. The term trituration means____________?

A. Lysing amalgam alloy
B. Mixing of amalgam alloy and mercury
C. Removal of excess of mercury
D. None of the above

628. 4th state of matter is______________?
A. Liquid
B. Solid
C. Gas
D. Colloid

629. All of the following statements about an alginate impression are EXCEPT________________?
A. It will take up water and expand if kept wet
B. It may exhibit fluid exudates on the surface as a result of imbibition of water
C. It should be rapidly displaced from the mouth
D. It will shrink as a result of syneresis

630. Type I and Type II zinc oxide impression paste differ with respect to_______________?
A. Water content
B. Their hardness after setting
C. Their use
D. Eugenol content