medical MCQs – Page 428

Practise multiple-choice questions from medical for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

8541. Modern dental noble metal casting alloys generally have equiaxed fine grain structures because of the incorporation of small amounts of______________?
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A. Irridium

B. Indium

C. Palladium

D. Chromium

8542. Setting of POP is result of______________?
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A. Reaction between hemihydrate and hihydrate

B. Nucleation and growth of CaSo4 H2O crystals

C. Difference in solubility of CaSo4 H2O + CaSO4+ 2H2O

D. Reaction between CaSO4+ 2H2O and water

8543. Brush heap structure is found in______________?
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A. Polyether

B. Condensation silicone

C. Agar

D. Zinc oxide impression material

8544. Placing cast under tap water is to be avoided as______________?
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A. H2O interferes with hygroscopic expansion

B. H2O interferes with Crystallization of dihydrate

C. Gypsum is slightly soluble in water and the surface of the cast will be eroded

D. H2O inhibits polymerization of dental resin

8545. The main ingredient in dental plaster in_______________?
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A. Calcium sulphate hemihydrate

B. Calcium anhydrate

C. Calcium phosphate

D. Calcium sulphate dihydrate

8546. Minimum flow of Type-I impression compound at mouth temperature is___________________?
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A. 6%

B. 10%

C. 8%

D. 4%

8547. Boxing wax is also called as________________?
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A. Utility wax

B. Sticky wax

C. Carding wax

D. Inlay wax

8548. Impression plaster containing potato starch is called______________?
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A. Anti expansion solution

B. Soluble plaster

C. Die stones

D. Plaster of paris

8549. Dustless alginate is produced by______________?
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A. Adding heavy metal salts

B. Coating with dihydric alcohol

C. Altering the matrix

D. Reducing the diatomaceous earth

8550. Which of the following impression materials is easy to pour and difficult to remove the stone cast from the impression ?
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A. Polyether

B. Condensation polysilicone

C. Polysulfide

D. Addition polysilicone

8551. The American dental association (ADA) specification number for non-aqueous elastomeric dental impression material is______________?
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A. 21

B. 19

C. 20

D. 26

8552. Which of the following increases castability of base metal alloys________________?
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A. Carbon

B. Beryllium

C. Molybdenum

D. Tin

8553. Impression compound is characterized by all of the following except_______________?
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A. Is a thermoset material

B. Low coefficient of thermal conductivity

C. Shows increased flow when kneaded with water

D. Warps at room temperature

8554. During setting of alginate impression materials________________?
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A. Trisodium phosphate reacts with calcium sulphate

B. Material in contact with soft tissues sets last

C. Trisodium phosphate reacts with sodium alginate

D. Colloidal changes to sol

8555. The main difference between dental stone and dental plaster is______________?
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A. Chemical composition

B. Solubility in water

C. Self life

D. Sharpe and size of particles
8556. Cobalt-Chrominum alloys contains_______________?
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A. 20% gold

B. 30% cobalt and 60% chrominum

C. 1% palladium

D. 60% cobalt and 30% chrominum
8557. Glossy smooth margins of a casting are due to_____________?
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A. Investment breakdown

B. Incomplete wax elimination

C. Incomplete gas elimination

D. Shrinkage of alloy on cooling

8558. Finer particle size of silica______________?
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A. Normal setting expansion

B. Slower the hygroscopic expansion

C. No setting expansion

D. Greater the hygroscopic expansion
8559. The setting time of irreversible hydrocolloids can be decreased by_____________?
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A. None of the above

B. Lowering the temperature of water used for mixing

C. Raising the temperature of water used for maxing

D. Using excess water for maxing

8560. The setting expansion of gypsum products can be reduced by________________?
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A. Increased spatulation

B. Less water powder ratio

C. Adding potassium sulfate

D. Allowing setting under water