561. Amalgam restorations give the best clinical service when the residual mercury content is_______________?

A. 38-42%
B. 48-52%
C. 58-62%
D. 68-72%

562. Percentage of tin in low copper alloy is______________?

A. 30-35%
B. 26-28%
C. 13-32%
D. 22-30%

563. Cause of expansion in zinc containing amalgam is_____________?

A. Zinc and water
B. Water
C. Hydrogen
D. Nascent oxygen

564. What is common in amalgam and ceramics ?

A. More compressive strength but less tensile strength
B. More compressive strength and tensile strength
C. Less compressive strength but more tensile strength
D. Less compressive strength and tensile strength

565. Which of the following constituents of amalgam alloy decreases expansion____________?

A. Copper
B. Zinc
C. Silver
D. Tin

566. The higher the Hg alloy ratio in dental amalgam________________?

A. Higher the strength
B. Lower the creep value
C. More matrix matrial formed
D. More gamma 1 phase formed

567. In non zinc containing dental amalgam alloy the percentage of zinc present is______________?

A. Less than 0.02%
B. Less than 0.1%
C. Less than 0.01%
D. None of the above

568. High copper dental amalgams are superior to other amalgams because high copper dental amalgems______________?

A. Have less marginal breakdown
B. Are workable at lower Hg-alloy ratio
C. Have a higher ratio of tensile to compressive strength
D. Have less resistance to tarnish and corrosion

569. The largest component of amalgam alloy is_____________?

A. Silver
B. Tin
C. Zinc
D. Copper

570. During amalgamation, trituration is done to_____________?

A. Dissolve the alloy in mercury
B. Coat the alloy particle with mercury
C. Remove excess mercury from the amalgam
D. Dissolve Hg in alloy


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