Metallurgy Most Important MCQs

1 - 18-B Stainless steel orthodontic wire has_______________?

---

A. 18% Nickel 8% Chrominum

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B. 18% Chromium 8% Nickel

---

C. 18% Chromium 8% Cobalt

---

D. 18% Carbon 8% Iron

---

18% Chromium 8% Nickel

2 - A common electrolyte used for plating copper indirect dies is_______________?

---

A. Copper cynide

---

B. Ionic copper

---

C. Acidic copper sulfate

---

D. Silver cyanide

---

Acidic copper sulfate

3 - A highly polished surface on a metallic dental restoration aids considerably in the prevention of the____________?

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A. Dimensional change

---

B. Thermal conductivity

---

C. Warpage

---

D. Tarnish and corrosion

---

Tarnish and corrosion

4 - A thinner mix of a gypsum bonded investment will_______________?

---

A. Produce a smoother casting

---

B. Decrease setting expansion

---

C. Increase setting expansion

---

D. Increase thermal expansion

---

Decrease setting expansion

5 - 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

---

Increase its fusion temperature

6 - Advantage of titanium over other base metal alloys_______________?

---

A. Low weight

---

B. Low cost

---

C. Low strength

---

D. Low melting point

---

Low weight

7 - Air bubbles formed on the surface of casting is probably due to________________?

---

A. Improper casting pressure

---

B. Improper heating of the investment

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C. Improper angulation of sprue

---

D. Improper wetting of the wax pattern by the investment

---

Improper wetting of the wax pattern by the investment

8 - All of the following statements about cast cobalt alloy are true EXCEPT_____________?

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A. They have a modulus of elasticity twice that of gold alloys

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B. They are more rigid than gold alloys

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C. They have higher ductility than gold alloys

---

D. They have a lower proportional limit than gold alloys

---

They have higher ductility than gold alloys

9 - Annealing is also known as_______________?

---

A. Soft hardening treatment

---

B. Hard hardening treatment

---

C. Precipitating heat treatment

---

D. Stress relieving heat treatment

---

Stress relieving heat treatment

10 - Apart from composites and ceramics, another material that could be copy milled easily and inexpensively is_________________?

---

A. Molybdenum

---

B. Germanium

---

C. Titanium

---

D. Chromium

---

Titanium

11 - Asbestos liner is used in a casting ring to________________?

---

A. Facilitate venting of the mold

---

B. Retard the heating of the investment

---

C. Permit expansion of the world

---

D. All of the above

---

Permit expansion of the world

12 - Austenite is an alloy of iron of and carbon with the iron in______________?

---

A. Alpha form

---

B. Beta form

---

C. Gamma form

---

D. None of the above

---

Gamma form

13 - Back pressure porosity can be avoided by________________?

---

A. Using asbestos linear

---

B. Placing the sprue at least one quarter inch away form the end of casting ring

---

C. Preventing rapid heating the investment in burnout oven

---

D. Using a short and wide sprue

---

Placing the sprue at least one quarter inch away form the end of casting ring

14 - Binder in phosphate bonded investment is______________?

---

A. Magnesium oxide & Phosphate

---

B. Magnesium oxide & Phosphoric acid

---

C. Magnesium oxide & Monoammonium phosphate

---

D. Magnesium oxide & Ortho Phosphoric acid

---

Magnesium oxide & Monoammonium phosphate

15 - Binder used in Gypsum investment is_________________?

---

A. Silica

---

B. Quartz

---

C. Cristobolite

---

D. Calcium sulphate monohydrate

---

Calcium sulphate monohydrate

16 - Boxing wax is also called as________________?

---

A. Carding wax

---

B. Inlay wax

---

C. Utility wax

---

D. Sticky wax

---

Carding wax

17 - 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

---

Flaring the point of the sprue attachment

18 - Casting shrinkage is compensated by_______________?

---

A. Thermal expansion

---

B. Hygroscopic expansion

---

C. Wax expansion

---

D. All of the above

---

All of the above

19 - Cleaning of base metal alloy is done by______________?

---

A. Warm HCI

---

B. Cold HF

---

C. Cold H2SO4

---

D. Sand blasting with aluminium oxide

---

Sand blasting with aluminium oxide

20 - Cobalt-Chrominum alloys contains_______________?

---

A. 30% cobalt and 60% chrominum

---

B. 60% cobalt and 30% chrominum

---

C. 1% palladium

---

D. 20% gold

---

60% cobalt and 30% chrominum

21 - Compared with noble metals, base metals show_______________?

---

A. Increased hardness

---

B. Increased ductility

---

C. Better biocompatibility

---

D. Increased density

---

Increased hardness

22 - Component of inlay wax which makes it flake resistant is_____________?

---

A. Paraffin

---

B. Carnauba

---

C. Gum dammar

---

D. Canadelila

---

Gum dammar

23 - Corrosion of stainless steel is due to formulation of_________________?

---

A. Chromium carbide

---

B. Carbon carbide

---

C. Iron carbide

---

D. Nickel carbide

---

Chromium carbide

24 - Crucible indicated for casting base metal alloys is______________?

---

A. Carbon crucible

---

B. Clay crucible

---

C. Quartz crucible

---

D. High melting plastic crucible

---

Quartz crucible

25 - Dendrites in cst alloys form by mechanism of_________________?

---

A. Constitutional superconductivity

---

B. Constitutional supercooling

---

C. Constitutional supergriting

---

D. Constitutional supergraining

---

Constitutional supercooling

26 - 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

---

Incomplete evacuation of gases

27 - During soldering, the solidus temperature of the filler material should be_____________?

---

A. Greater than the substrate material

---

B. Lesser than the substrate material

---

C. Equal to the substrate material

---

D. Temperature not relevant

---

Lesser than the substrate material

28 - Fins and spines on the casting is seen due to_______________?

---

A. Prolonged heating:

---

B. Rapid heating me

---

C. Water film contamination

---

D. Too high pressure during casting

---

Rapid heating me

29 - 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

---

Remove the oxides formed on the gold alloy

30 - Function of carnauba wax_________________?

---

A. To provide a smooth and glossy surface

---

B. Increase toughness

---

C. Decrease toughness

---

D. Decrease flow at room temperature

---

Decrease flow at room temperature

31 - Function of wetting agents used in casting procedure is_________________?

---

A. To felicitate wetting of ring liner

---

B. To felicitate mixing investment

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C. To reduce contact angle of liquid with max surface

---

D. For better wax elimination

---

To reduce contact angle of liquid with max surface

32 - 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

---

¼ inch

33 - 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

---

Gas inclusion porosity

34 - Glossy smooth margins of a casting are due to_____________?

---

A. Shrinkage of alloy on cooling

---

B. Investment breakdown

---

C. Incomplete wax elimination

---

D. Incomplete gas elimination

---

Incomplete wax elimination

35 - Gold content of an 18 carat alloy is______________?

---

A. 0.25

---

B. 0.5

---

C. 0.75

---

D. 1

---

0.75

36 - Gypsum bonded investment should not be heated over______________?

---

A. 700°C

---

B. 1,300°C

---

C. 1,063°C

---

D. 900°C

---

700°C

37 - Heat hardening is the process done at_______________?

---

A. Heating 750°C and slowly cooling to zero degree

---

B. Heating quickly upto 450°C followed by sudden quenching

---

C. Heating upto 250°C for 15 to 30 min

---

D. Heating at 750°C and then quenching to room temperature

---

Heating upto 250°C for 15 to 30 min

38 - Ideal requirement of metal ceramic casting____________?

---

A. Low fusing ceramic and high fusing alloys

---

B. Matching of coefficients of thermal expansion of ceramics and alloy

---

C. Bonding between ceramic and alloy

---

D. All of the above

---

All of the above

39 - Impurities in casting is removed by________________?

---

A. Annealing

---

B. Degassing

---

C. Pickling

---

D. Conditioning

---

Pickling

40 - In a metal ceramic crown for a FPD the function of tin, indium which are readily oxidized minor constituents is to________________?

---

A. Improve bonding

---

B. Decrease porosity

---

C. They react with the porcelain opaque layer, which masks the metal

---

D. Improves the thermal expansion between the metal and porcelain

---

Improve bonding

41 - In a patient with allergy to costume jewelry, which of the following is contraindicated______________?

---

A. High gold

---

B. Low gold

---

C. Palladium – Ag

---

D. Ni – Cr

---

Ni – Cr

42 - In Base metal alloys, Corrosion resistance occurs due to___________________?

---

A. Passivity

---

B. High Fusion Temperature

---

C. High Molecular Weight

---

D. Co-efficient of Thermal Expansion

---

Passivity

43 - Incomplete casting is the result of_____________?

---

A. More porous investment in the mould

---

B. Narrow sprue diameter

---

C. Hollow sprue pin

---

D. Large reservoir

---

Narrow sprue diameter

44 - Indium in metal alloys_______________?

---

A. Improve bonding

---

B. Harden the metal ceramic Ag-Pd alloy

---

C. Both A and B

---

D. None of the above

---

Both A and B

45 - Inlay wax is used to_______________?

---

A. Temporarily cement inlays:

---

B. Make inlay wax patterns

---

C. Invest inlay patterns

---

D. Box models

---

Make inlay wax patterns

46 - Investment material used for cobalt-chromium alloys is_____________?

---

A. Gypsum bonded

---

B. Phosphate bonded

---

C. Silica bonded

---

D. None of the above

---

Phosphate bonded

47 - Linear coefficient of thermal expansion of metal used for metal caramic restoration range from________________?

---

A. 11.5-12.5×10-6/°C

---

B. 10.5-11.5×10-6/°C

---

C. 13.5-14.5×10-6/°C

---

D. 16.5-17.5×10-6/°C

---

13.5-14.5×10-6/°C

48 - Localised shrinkage porosity is seen when there________________?

---

A. Thin sprue

---

B. No reservoir

---

C. Investment heated strongly

---

D. Inadequate air discharge

---

Thin sprue

49 - Mechanical properties of Cp Titanium are similar to alloys_____________?

---

A. Type III and Type IV gold

---

B. Type V and type VI gold

---

C. Type VII and type VIII gold

---

D. None of the above

---

Type III and Type IV gold

50 - Microstructure of cobalt chromium alloy in cast condition is______________?

---

A. Fibrous

---

B. Homogeneous

---

C. Inhomogenous

---

D. amorphous

---

Inhomogenous

51 - Modern dental noble metal casting alloys generally have equiaxed fine grain structures because of the incorporation of small amounts of______________?

---

A. Chromium

---

B. Indium

---

C. Irridium

---

D. Palladium

---

Irridium

52 - Most biocompatible material in oral cavity is_______________?

---

A. Platinium

---

B. Palladium

---

C. Titanium

---

D. Gold

---

Titanium

53 - Mouth temperature waxes are_______________?

---

A. Iowa wax

---

B. Modeling wax

---

C. Green stick wax

---

D. None of the above

---

Iowa wax

54 - Nickel is added to wrought gold alloys as______________?

---

A. Strengtherner

---

B. Hardener

---

C. Whitens the alloy

---

D. Scavenger

---

Strengtherner

55 - Nickel-Titanium alloy has__________________?

---

A. Unreliable spring back

---

B. low spring back

---

C. Minimal spring back

---

D. None of the above

---

None of the above

56 - NiTi alloy have_______________?

---

A. Shape memory

---

B. Hyper rigidity

---

C. Corrosion resistance

---

D. Weldable properties

---

Shape memory

57 - Passivating alloys are_______________?

---

A. Cr, Al, Ti

---

B. Cr, Mo, Ti

---

C. Cr, Gold, Ti

---

D. Cr, Fe, Ti

---

Cr, Al, Ti

58 - Percentage of gold in high noble alloy is______________?

---

A. N 25%

---

B. 0.25

---

C. >40%

---

D. 0

---

>40%

59 - Pickling________________?

---

A. Is accomplished by soaking the casting in baking soda

---

B. Causes porosity in gold

---

C. Removes surface oxides from gold castings

---

D. Remove investment from gold casting

---

Removes surface oxides from gold castings

60 - Quartz in investment material is added for_______________?

---

A. Strength

---

B. Expansion components for casting shrinkage

---

C. Decrease strength

---

D. Contraction

---

Expansion components for casting shrinkage

61 - Quartz is added to gypsum bonded investment to______________?

---

A. Increase the strength

---

B. Counter balance contraction of gypsum during heating

---

C. aid in hygroscopic expansion

---

D. Increase the shelf life of investment

---

Counter balance contraction of gypsum during heating

62 - Reduction in the fusion temperature of dental gold casting alloys is caused by presence of______________?

---

A. Platinum

---

B. Copper

---

C. Silver

---

D. Gold

---

Copper

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

---

A. High quality iron

---

B. Chrome

---

C. Cobalt

---

D. Nickel

---

Chrome

64 - Setting expansion is advantageous in__________________?

---

A. Casts

---

B. Models

---

C. Investment

---

D. Dies

---

Investment

65 - Shape memory in NiTi is because of stress induced form__________________?

---

A. Austenite to martensite

---

B. Martensite to austenite

---

C. Ferrite to austenite

---

D. Austenite to ferrite

---

Austenite to martensite

66 - Shape memory is seen in________________?

---

A. Stainless steel wire

---

B. NITTINOL wire

---

C. TMA wire

---

D. Aluminium

---

NITTINOL wire

67 - Silica sol__________________?

---

A. Is applied to the walls of the investment to produce hygroscopic expansion

---

B. Increase the strength and the setting expansion of the phosphate-bonded investment

---

C. Acts as a retarder in the silica bonded investments

---

D. Acts as a refractory in the Silica bonded investments

---

Increase the strength and the setting expansion of the phosphate-bonded investment

68 - Silver plated dyes use an electrolytic bath of_______________?

---

A. Silver fluorides

---

B. Silver cyanide

---

C. Silver bromide

---

D. Silver iodide

---

Silver cyanide

69 - Softening heat treatment of alloy increases_________________?

---

A. Tensile strength

---

B. Proportional limit

---

C. Ductility

---

D. Hardness

---

Ductility

70 - Solder and flux used for joining Elgiloy wires are_____________?

---

A. Gold solder and borax flux

---

B. Gold solder and fluoride flux

---

C. Silver Solder and borax flux

---

D. Silver solder and fluoride flux

---

Silver solder and fluoride flux

71 - Stabilization of stainless steel is achieved by adding____________?

---

A. Carbon

---

B. Chromium

---

C. Nickel

---

D. Titanium

---

Titanium

72 - Stages of annealing in order_________________?

---

A. Recovery recrystallization grain growth

---

B. Recrystallization recovery, grain growth

---

C. Grain Growth Recrystallization recovery

---

D. Melting point, grain growth, Recrystallization

---

Recovery recrystallization grain growth

73 - Stainless steel is used mostly in dentistry_________________?

---

A. To strength amalgam

---

B. In orthodontic wires

---

C. To construct clasps for partial dentures

---

D. To replace internal gold restorations

---

In orthodontic wires

74 - Stainless steel orthodontic wire can be hardened by________________?

---

A. Tempering

---

B. Work hardening

---

C. Age hardening

---

D. Precipitation hardening

---

Work hardening

75 - Sub surface porosity can be decreased by_______________?

---

A. Decreasing the sprue length

---

B. Decreasing the sprue thickness

---

C. Increasing the melting temperature

---

D. Increasing the mould temperature

---

Decreasing the sprue thickness

76 - Suck back porosity in the casting can be eliminated by________________?

---

A. Increasing the mould metal temperature difference

---

B. Increasing the flow of molten metal

---

C. Flaring the point of the sprue attachment

---

D. All of the above

---

Flaring the point of the sprue attachment

77 - Suck back porosity is due to_________________?

---

A. Attached impurities on undersurface of casting

---

B. Hot spot

---

C. No rapid cooling

---

D. Inadequate melting temperature

---

Hot spot

78 - Tempering of steel cause________________?

---

A. Increases its toughness

---

B. Increases hardness

---

C. Increase ductility

---

D. decreases its toughness

---

Increase ductility

79 - The base constituents of dental waxes come from three main sources except______________?

---

A. Animal

---

B. Mineral

---

C. Insect

---

D. Vegetable

---

Animal

80 - The best fuel gas when used with oxygen is______________?

---

A. Hydrogen

---

B. Natural gas

---

C. Propane

---

D. Acetylene

---

Propane

81 - The best pickling solution for gypsum bonded investment is_______________?

---

A. Hydrochloric acid

---

B. Nitric acid

---

C. Sulphuric acid

---

D. Phosphoric acid

---

Hydrochloric acid

82 - The castability of chromium-cobait base metal alloys when compared to gold based noble metal alloys is_______________?

---

A. More

---

B. Less

---

C. Equal

---

D. Depends on the alloy type

---

Less

83 - The component in very minor quantity in stainless steel that changes the properties to a maximum level is____________?

---

A. Carbon

---

B. Molybdenum

---

C. Chromium

---

D. Nickel

---

Carbon

84 - The contraction of gold alloy on solidifying is approximately_____________?

---

A. 0.004

---

B. 0.014

---

C. 0.024

---

D. 0.034

---

0.014

85 - The deoxidizing agent added to dental alloys is______________?

---

A. Palladium

---

B. Silver

---

C. Copper

---

D. Zinc

---

Zinc

86 - The effects associated with cold working can be eliminated by a heat treatment called______________?

---

A. Age hardening heat treatment

---

B. Annealing heat treatment

---

C. Homogenization heat treatment

---

D. Solution heat treatment

---

Annealing heat treatment

87 - The function of a sprue is to_______________?

---

A. Form an opening of molten metal to enter the mold

---

B. Help polish cast restorations

---

C. Eliminate air bubbles on the wax pattern

---

D. Reproduce fine detail

---

Form an opening of molten metal to enter the mold

88 - The gold alloys used for casting contain at least…. percent of precious metal according to ADA specification number 5________________?

---

A. 55

---

B. 65

---

C. 75

---

D. 85

---

75

89 - The inlay wax most commonly used for direct technique_____________________?

---

A. Type 1

---

B. Type 2

---

C. Type 3

---

D. Type 4

---

Type 1

90 - The linear solidification shrinkage of Type IV Ni-Cr based alloys is_______________?

---

A. 0.023

---

B. 0.0156

---

C. 0.0137

---

D. 0.03

---

0.023

91 - The main form of iron carbide found in 18-8 steel________________?

---

A. Martensite

---

B. Ferrite

---

C. Austenite

---

D. Pearlite

---

Austenite

92 - The main ingredient of inlay wax is__________________?

---

A. Candellila wax

---

B. Paraffin wax

---

C. Carnauba wax

---

D. Gum dammar

---

Paraffin wax

93 - The maximum carbon content of steel used in dentistry is__________________?

---

A. 0.19

---

B. 0.02

---

C. 0.017

---

D. 0.04

---

0.017

94 - The most commonly used Titanium alloy for dental and medical purposes is________________?

---

A. Ti 6Al 4V

---

B. Ti 5Al 4V

---

C. Ti 5Al 5V

---

D. Ti 6Al 6V

---

Ti 6Al 4V

95 - The pattern for the metallic framework of a removable partial denture is fabricated from________________?

---

A. Inlay wax type-II

---

B. Boxing wax

---

C. Modelling wax

---

D. Casting wax

---

Casting wax

96 - The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called__________?

---

A. Pinhole porosity

---

B. Gas inclusion porosity

---

C. Micro porosity

---

D. Subsurface porosity

---

Subsurface porosity

97 - The purity of gold is expressed in________________?

---

A. Carats

---

B. Percentage

---

C. Fineness

---

D. Gram

---

Fineness

98 - The rapid decrease in tensile strength and increase in ductility of a wrought metal is seen in which stage of annealing ?

---

A. Recovery stage

---

B. Recrystallisation stage

---

C. Grain growth stage

---

D. All of the above

---

Recrystallisation stage

99 - The rate of tarnish and corrosion of class II cast material having VHN 200 is_______________?

---

A. 0

---

B. 2 to 3%

---

C. 5 to 10%

---

D. <1%

---

0

100 - The solvent flux used for base metal soldering is_______________?

---

A. Boric acid

---

B. Borax

---

C. Fluoride

---

D. Rouge

---

Borax

101 - The sprue in wax pattern should be placed________________?

---

A. At right angle

---

B. At 45°C angle

---

C. At obtuse angle

---

D. It depend upon type of wax pattern

---

At 45°C angle

102 - The standard perforated tray for us with alginate impression materials may be brought to more customized contour by_______________?

---

A. Utility wax

---

B. Base plate wax

---

C. Beading wax

---

D. Boxing wax

---

Utility wax

103 - The strength of a gypsum investment is dependent on_______________?

---

A. Carbon content

---

B. Silica content

---

C. Gypsum

---

D. Copper

---

Gypsum

104 - The term ordered hardening heat treatment used in which of the following dental alloys ?

---

A. Gold-Copper

---

B. Nickel-Chromium

---

C. Nickel-Titanium

---

D. Silver-Palladium

---

Gold-Copper

105 - The yield strength of AUstenite (NiTi alloy) is______________?

---

A. 100 Mpa

---

B. 240 Mpa

---

C. 560 Mpa

---

D. 700 Mpa

---

560 Mpa

106 - Titanium casting is done_____________?

---

A. Under vacuum in argon atmosphere

---

B. Under air pressure in nitrogen atmosphere

---

C. In specially fabricated aluminium vanadium

---

D. Using CAD-CAM technique

---

Under vacuum in argon atmosphere

107 - Tublulence of molten gold is due to _____________?

---

A. Impurities in gold

---

B. Improper venting

---

C. A and B

---

D. None of the above

---

None of the above

108 - Wax pattern is ideally invested immediately to decrease the dimensional changes caused by_______________?

---

A. Decrease flow

---

B. Continuous expansion

---

C. Relaxation of the internal stresses

---

D. Water loss

---

Relaxation of the internal stresses

109 - Waxes are used for_______________?

---

A. Primary impression

---

B. Corrective impressions

---

C. Impression of single tooth

---

D. None of the above

---

Corrective impressions

110 - 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

---

Ease of pouring an impression

111 - Which of the following cast gold alloys is used for fabricating partial denture frameworks______________?

---

A. Type I – Soft

---

B. Type II – Hard

---

C. Type III – Hard

---

D. Type IV – Extra Hard

---

Type IV – Extra Hard

112 - Which of the following decrease with strain hardening______________?

---

A. Surface hardness

---

B. Strength

---

C. Proportion limit

---

D. Corrosion resistance

---

Corrosion resistance

113 - Which of the following fuel gases is the best choice of heat source to carry out soldering process ?

---

A. Propane

---

B. Acetylene

---

C. Natural gas

---

D. Hydrogen

---

Propane

114 - Which of the following fuel gases used for soldering, has the highest heat content______________?

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A. Hydrogen

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B. Natural gas

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C. Acetylene

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D. Propane

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Propane

115 - Which of the following increases castability of base metal alloys________________?

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A. Tin

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B. Beryllium

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C. Molybdenum

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D. Carbon

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Beryllium

116 - Which of the following is function of fluoride flux in soldering process ?

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A. It prevents the formation of copper oxide

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B. It prevents the formation of chromium oxide or dissolves chromic oxide layer

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C. It prevents the flow of material in undesirable area

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D. Increase the strength of solder

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It prevents the formation of chromium oxide or dissolves chromic oxide layer

117 - Which of the following refractory is used to counteract most of the expansion________________?

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A. Quartz

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B. Cristobalite

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C. Tridymite

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D. Corundum

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Cristobalite

118 - Which of the following will produce the most rigid restoration for framework of same dimension ?

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A. Wrought alloy

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B. Palladium alloys

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C. Cobalt-chrome alloys

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D. Partial denture casting gold in hardened condition

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Cobalt-chrome alloys

119 - Which of the following zones is used for melting alloy during casting______________?

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A. Reducing flame

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B. Oxidizing flame

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C. Green flame

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D. All of the above

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Reducing flame

120 - Which of the waxes are derived from the lignite_________________?

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A. Paraffin wax

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B. Inlay wax

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C. Microcrystalline wax

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D. Montan wax

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Montan wax

121 - Which one of the following categories of dental materials has the highest thermal conductivity_________________?

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A. Unfilled acrylic plastics

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B. Gold alloys

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C. Porcelains

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D. Zinc phosphate cements

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Gold alloys

122 - Which one of the following elements is NOT added is small amount to be used as grain refiners ?

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A. Iridium

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B. Ruthinium

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C. Indium

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D. Platinum

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Platinum

123 - Which one of the following is most elastic ?

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A. a titanium

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B. B titanium

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C. Chrome-cobalt-nickel

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D. Nickel-titanium

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Nickel-titanium

124 - Which zone is the hottest and efficient burning zone of the flame used for casting ?

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A. Oxidizing zone

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B. Reducing zone

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C. Combustion zone

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D. None of the above

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Oxidizing zone

125 - Who was the first person to introduce cast inlay restoration into dentistry ?

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A. William H Taggart

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B. Buonocore

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C. G.V. Black

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D. Bowen

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William H Taggart

126 - With indirect spruing. Which one of the following porosities can be minimised_______________?

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A. Back pressure porosity

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B. Localized shrinkage porosity

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C. Pin hole porosity

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D. Micro porosity

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Localized shrinkage porosity

127 - Within an hour after cementation of cast gold onlay patient complains of shooting pain every time the teeth comes together Most probable explanation is ______________?

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A. Supracocclusion of restoration

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B. Retained cement in gingival sulcus

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C. Excess acid in mix

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D. Galvanic current caused by gold onlay occluding with a large restoration

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Galvanic current caused by gold onlay occluding with a large restoration

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