Free Metals and Alloys MCQs with Answers

• A. Type VII and type VIII gold
• B. Type V and type VI gold
• C. Type III and Type IV gold
• D. None of the above

Explanation: Commercially pure titanium has mechanical properties broadly comparable to Type III and Type IV gold alloys, although titanium is much…

• A. Age hardening heat treatment
• B. Solution heat treatment
• C. Homogenization heat treatment
• D. Annealing heat treatment

Explanation: Annealing removes the effects of cold working by recovery and recrystallization, restoring ductility and reducing residual stress.

• A. Back pressure porosity
• B. Localized shrinkage porosity
• C. Pin hole porosity
• D. Micro porosity

Explanation: Indirect spruing provides a more effective metal reservoir and feeding path, so localized shrinkage porosity is reduced.

• A. 2.3%
• B. 1.56%
• C. 1.37%
• D. 3%

Explanation: Type IV nickel-chromium alloys show approximately 2.3% linear solidification shrinkage.

• A. Type I - Soft
• B. Type II - Hard
• C. Type III - Hard
• D. Type IV - Extra Hard

Explanation: Partial denture frameworks require the greatest strength and hardness among cast gold alloy types, so Type IV, extra-hard alloy, is used.

• A. Irridium
• B. Indium
• C. Chromium
• D. Palladium

Explanation: Small amounts of iridium act as grain refiners, producing a fine equiaxed grain structure in noble metal casting alloys.

• A. Hardener
• B. Strengtherner
• C. Whitens the alloy
• D. Scavenger

Explanation: Nickel is added to wrought gold alloys primarily to increase strength, although it can also increase hardness and lighten the colour.

• A. Grain Growth Recrystallization recovery
• B. Recrystallization recovery, grain growth
• C. Recovery recrystallization grain growth
• D. Melting point, grain growth, Recrystallization

Explanation: Annealing progresses through recovery, recrystallization, and finally grain growth as temperature or treatment time increases.

• A. Gold-Copper
• B. Nickel-Chromium
• C. Nickel-Titanium
• D. Silver-Palladium

Explanation: Ordered hardening, also called ordering or age hardening, is characteristic of gold-copper alloys because heat treatment forms an ordered…

• A. Counter balance contraction of gypsum during heating
• B. Increase the strength
• C. aid in hygroscopic expansion
• D. Increase the shelf life of investment

Explanation: Quartz undergoes thermal expansion during heating, which compensates for the contraction of gypsum in a gypsum-bonded investment.

• A. Soft hardening treatment
• B. Stress relieving heat treatment
• C. Precipitating heat treatment
• D. Hard hardening treatment

Explanation: Annealing is a stress-relieving heat treatment that reduces internal stresses and softens a cold-worked alloy.

• A. Natural gas
• B. Acetylene
• C. Propane
• D. Hydrogen

Explanation: Propane is commonly preferred for dental soldering because it provides adequate, controllable heat without the excessively intense flame…

• A. Gold solder and borax flux
• B. Gold solder and fluoride flux
• C. Silver Solder and borax flux
• D. Silver solder and fluoride flux

Explanation: Elgiloy is a cobalt-chromium alloy with a tenacious oxide layer, so silver solder is used with a fluoride flux to dissolve or disrupt…

• A. Rapid heating me
• B. Prolonged heating:
• C. Water film contamination
• D. Too high pressure during casting

Explanation: Rapid heating can crack the investment, allowing molten alloy to enter the cracks and form thin fins or spines on the casting.

• A. More
• B. Less
• C. Equal
• D. Depends on the alloy type

Explanation: Chromium-cobalt base-metal alloys generally have poorer castability than gold alloys because they have higher melting temperatures…

• A. Co-efficient of Thermal Expansion
• B. High Fusion Temperature
• C. High Molecular Weight
• D. Passivity

Explanation: Base-metal alloys such as chromium-containing alloys resist corrosion through passivation, in which a thin, adherent oxide film blocks…

• A. Lesser than the substrate material
• B. Greater than the substrate material
• C. Equal to the substrate material
• D. Temperature not relevant

Explanation: The filler metal must melt and flow before the substrate begins to melt, so its solidus temperature must be lower than the substrate's…

• A. Tin
• B. Beryllium
• C. Molybdenum
• D. Carbon

Explanation: Beryllium lowers the melting temperature and improves fluidity and castability of cobalt-chromium base-metal alloys.

• A. Hydrogen
• B. Natural gas
• C. Propane
• D. Acetylene

Explanation: Propane has the greatest heat content per unit volume among the listed fuel gases, which is why it is useful for soldering and heating.

• A. Iridium
• B. Ruthinium
• C. Platinum
• D. Indium

Explanation: Iridium and ruthenium are potent grain refiners used in small quantities in dental casting alloys, while indium is mainly added for…