Engineering Questions with Answers - Multiple Choice Questions

Materials Science MCQ’s – Amorphous Solids

1 - Question

Which of the following properties is generally exhibited by amorphous solids?
a) Anisotropy
b) Glass-transition
c) Equal strength of all bonds
d) All of the mentioned
View Answer Answer: b
Explanation: Due to random organization of particles, amorphous solids have the same physical properties along all directions, or are isotropic. Random organization of particles also results in unequal bond strengths. Upon cooling, amorphous solids turn into a brittle glass-like state from a flexible rubber-like state. This is called glass-transition.



2 - Question

Metal glass was first prepared at:
a) California Institute of Technology
b) Massachusetts Institute of Technology
c) Technion
d) University of Michigan
View Answer Answer: a
Explanation: Metal glass or amorphous metal was reportedly first produced by W. Klement (Jr.), Willens and Duwez in 1960 at Caltech. It was prepared by rapid cooling (~ 1 MK/s) of molten metal alloys.



3 - Question

Polycrystalline solids are isotropic.
a) True
b) False
View Answer Answer: a
Explanation: Anisotropy is a characteristic behavior shown by ideal crystals. However, the presence of flaws like grain boundaries causes the solid to deviate from crystalline properties.



4 - Question

Metal glasses differ from their crystalline counterparts in many ways. Chief application(s) of metal glasses include(s):
a) Bullet-proof glasses
b) Power transformers
c) Conducting wires
d) All of the mentioned
View Answer Answer: b
Explanation: Amorphous metals are not transparent and have relatively lower electrical conductivity. However, most metal glasses possess high magnetic susceptibility and low coercivity.



5 - Question

Consider the following cooling diagram for an amorphous solid. Glass-transition temperature is represented as:
a) A
b) B
c) C
d) None of the mentioned
View Answer Answer: b
Explanation: An exact melting point does not exist for amorphous solids. An approximate glass-transition temperature is defined by extrapolating the cooling curve as shown.



6 - Question

Soda-lime glass is the most common type of glass. The component present in largest w/w percentage is:
a) SiO2
b) Al2O3
c) Na2O
d) CaO
View Answer Answer: a
Explanation: Glass inherits its transparency from crystalline SiO2, also called quartz. However, quartz has very high and narrow glass-transition. To overcome this, small amount of Na2 is added. CaO is also added to prevent water-solubility imparted by soda.



7 - Question

Lead-oxide glass is called “crystal glass” because:
a) It contains crystalline Pb
b) It contains SiO2 crystals
c) It contains PbO crystals
d) None of the mentioned
View Answer Answer: d
Explanation: Well, crystal glass is amorphous, not crystalline. This glass earns its name from its excellent decorative properties and high refractive index.



8 - Question

Crystallinity increases with increasing rate of cooling of a liquid.
a) True
b) False
View Answer Answer: b
Explanation: When a liquid is cooled rapidly, the particles get less time to move and arrange themselves in an orderly fashion and hence the crystallinity of the resulting solid decreases.

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