Matsci Multiple Choice Practice
List two molecular characteristics that are essential for elastomers. (1) Elastomers must experience a rise in temperature when stretched and (2) the modulus of elasticity decreases with increasing temperature. (1) Elastomers must be amorphous, having chains that are extensively coiled and kinked in the unstressed state and (2) there must be some crosslinking. (1) For elastomers to experience relatively large elastic deformations, the onset of plastic deformations must be delayed and (2) elastomers must have huge molecular weight. (1) Elastomer must not easily crystallize and (2) the lowest temperature at which rubber-like behavior persists is between -50 and -90oC.
(1) Elastomers must be amorphous, having chains that are extensively coiled and kinked in the unstressed state and (2) there must be some crosslinking
In X ray Diffraction Patterns for FCC, the smallest scattering angle corresponds to this family of planes (100) (111) (110) (200)
(111)
How does each of the following influence the tensile or yield strength of a semicrystalline polymer? (a) Molecular weight increase (b) Degree of crystallinity increase (c) Deformation by drawing (d) Annealing of an undeformed material (a) - increase, (b) - decrease,(c) - decrease, (d) - increase (a) - increase, (b) - increase, (c) - increase, (d) - increase (a) - non-direct influence, (b) - increase, (c) - decrease, (d) - increase (a) - decrease, (b) - increase, (c) - decrease, (d) - decrease
(a) - increase, (b) - increase, (c) - increase, (d) - increase
Which of the following describes galvanic pitting? Two metals/alloys of different compositions are coupled while exposed to an electrolyte. One element is preferentially removed as a result of corrosion. Corrosion that occurs preferentially along grain boundaries. Corrosion resulting from the combined action of an applied tensile stress and a corrosive environment. Corrosion that results from a difference in concentration of ions or dissolved gases in the electrolyte. Oxidation and reduction reactions that occur randomly over the surface. Localized corrosion that may be initiated at a surface defect. Corrosion resulting from the combined action of chemical attack and mechanical abrasion or wear.
Localized corrosion that may be initiated at a surface defect
Cathodic protection reduces the corrosion rate of a metal when an electrical connection is made to another metal that is Lower in the galvanic series. Higher in the galvanic series.
Lower in the galvanic series
What type of bonding cannot be found in ceramic Covalent ionic Metallic Secondary
Metallic
What type(s) of bonding would be expected for brass (a copper-zinc alloy)? Van der Waals bonding Covalent bonding with some van der Waals bonding Ionic bonding Metallic bonding
Metallic bonding
Corrosion is most serious for Metals Polymers Ceramics Glasses
Metals
In general the charge carrier density is the highest in Metals Semiconductors Insulators Polymers
Metals
The F- ion has an electron structure that is identical to which inert gas? Helium Argon Krypton Xenon Neon
Neon
Which of the following describes selective leaching? Two metals/alloys of different compositions are coupled while exposed to an electrolyte. One element is preferentially removed as a result of corrosion. Corrosion that occurs preferentially along grain boundaries. Corrosion resulting from the combined action of an applied tensile stress and a corrosive environment. Corrosion that results from a difference in concentration of ions or dissolved gases in the electrolyte. Oxidation and reduction reactions that occur randomly over the surface. Localized corrosion that may be initiated at a surface defect. Corrosion resulting from the combined action of chemical attack and mechanical abrasion or wear.
One element is preferentially removed as a result of corrosion
The direction of motion of a screw dislocation's line is ________ to the direction of an applied shear stress. parallel perpendicular
Perpendicular
Which of the following statements about the interatomic bonding in NaCl is correct Metallic Bonding Covalent Bonding Primarily ionic bonding with some covalent bonding Primarily covalent bonding with some ionic bonding
Primarily ionic bonding with some covalent bonding
Which of the following metals will have the lowest yield strength Pure copper with grain size .1 mm Pure copper with grain size .01 mm Pure copper with grain size .1 mm , rolled to reduce area by 20% Copper with 10% nickel and grain size .1 mm
Pure copper with grain size .1 mm
Which of the following is a (are) linear defect(s)? (More than One) An edge dislocation A Frenkel defect A screw dislocation A Schottky defect
Screw and Edge
The atoms surrounding a screw dislocation experience what kinds of strains? Tensile Strains Shear strains Compressive strains All the above Both B and C
Shear Strains
For a solution, which of the following is present in the higher concentration? Solvent Solute
Solvent
Name two common types of alloy that passivate. Copper and zinc Stainless steels and aluminum alloys Cast iron and silver
Stainless steels and aluminum alloys
How does grain size influence the strength of a polycrystalline material? Strengthfine-grained =Strengthcoarse-grained Strengthfine-grained < strengthcoarse-grained Strengthfine-grained > Strengthcoarse-grained
Strengthfine-grained > Strengthcoarse-grained
How does the theoretical strength of a solid material compare with its experimental strength? Strengththeoretical < strengthexperimental Strengththeoretical =Strengthexperimental Strengththeoretical > Strengthexperimental
Strengththeoretical > Strengthexperimental
As the temperature increases, in general, one expects The electrical conductivity of a metal decreases and the electrical conductivity of a semiconductor decreases The electrical conductivity of a metal decreases and the electrical conductivity of a semiconductor increases The electrical conductivity of a metal increases and the electrical conductivity of a semiconductor decreases The electrical conductivity of a metal increases and the electrical conductivity of a semiconductor increases
The electrical conductivity of a metal decreases and the electrical conductivity of a semiconductor increases
In the Ag-Au system where the two elements are mutually soluble, which statement is true? The melting temperature of the alloy depends on composition The number of components is 1 At any temperature the alloy will always be a single phase Ag and Au are mutually soluble because they are both noble metals
The melting temperature of the alloy depends on composition
In a unary phase disagram, the triple point is defined at a specific pressure and temperature. According to the Gibbs' phase rule select the following statement that is correct There is one or more degrees of freedom There are 3 components There is 1 phase There are no degrees of freedom
There are no degrees of freedom
The Gibbs' phase rule indicates that at a eutectic composition and temperature There are two phases in equilibrium There is one phase There are three phases The number of phases depends on the fraction of liquid transformed
There are three phases
Which of the following material properties is related to the skewness of the potential energy vs distance curve Melting Point Density Thermal Expansion Coefficient Young's Modulus
Thermal Expansion Coefficient
The total energy per unit volume that a ductile material can absorb before fracturing determines its Ductility Resilience Tensile Strength Toughness
Toughness
Which of the following describes galvanic corrosion? Two metals/alloys of different compositions are coupled while exposed to an electrolyte. One element is preferentially removed as a result of corrosion. Corrosion that occurs preferentially along grain boundaries. Corrosion resulting from the combined action of an applied tensile stress and a corrosive environment. Corrosion that results from a difference in concentration of ions or dissolved gases in the electrolyte. Oxidation and reduction reactions that occur randomly over the surface. Localized corrosion that may be initiated at a surface defect. Corrosion resulting from the combined action of chemical attack and mechanical abrasion or wear.
Two metals/alloys of different compositions are coupled while exposed to an electrolyte
Galvanizing involves applying a layer of what metal to the surface of steel? Iron Copper Nickel Zinc Aluminum
Zinc
Metals near the top of the galvanic series are A. cathodic. B. anodic. C. unreactive. D. reactive. E. both A and C. F. both B and D.
both A and C
As a metal is strain hardened, its ductility increases. decreases.
decreases
When all the electrons in an atom occupy the lowest possible energy states, the atom is said to be in its: regular state. ionized state. ground state. cold state.
ground state
the "atomic number" of an element refers to number of protons in the nucleus number of neutrons in the nucleus mass of nucleus charge of nucleus
number of protons in the nucleus
For pure metals, the recrystallization temperature is normally about 0.3Tm 0.1Tm 0.4Tm 0.2Tm
0.4Tm
CN for HCP is 4 6 8 12
12
Number of atoms in FCC unit cell 1 2 4 14
4
Atom 'A' has a higher bond energy, E0 than atom 'B', therefore: A has a higher melting temperature B has a higher melting temperature Melting points don't depend on bond energy A is solid at room temperature
A has a higher melting temperature
For many technologically important metal alloys, the usual state or microstructure is: an equilibrium one. a metastable one.
A metastable one
Reduction takes place at the cathode anode
Cathode
Which of the following defect pairs are likely to exist in ceramics Anion vacancy coupled to an anion interstitial Cation vacancy coupled to a cation interstitial Cation interstitial coupled to an anion vacancy Anion interstitial coupled to a cation vacancy
Cation vacancy coupled to a cation interstitial
Which of the following materials differs in classification from the rest Rubber Nylon Paper Clay
Clay
Which of the following describes stress corrosion? Two metals/alloys of different compositions are coupled while exposed to an electrolyte. One element is preferentially removed as a result of corrosion. Corrosion that occurs preferentially along grain boundaries. Corrosion resulting from the combined action of an applied tensile stress and a corrosive environment. Corrosion that results from a difference in concentration of ions or dissolved gases in the electrolyte. Oxidation and reduction reactions that occur randomly over the surface. Localized corrosion that may be initiated at a surface defect. Corrosion resulting from the combined action of chemical attack and mechanical abrasion or wear.
Corrosion resulting from the combined action of an applied tensile stress and a corrosive environment
Why type of bonding would be expected for a polymer Van der Waals bonding Metallic Bonding Ionic Bonding Covalent Bonding with some van der Waals bonding
Covalent Bonding with some van der Waals bonding
Ceramics usually have a combination of the following types of bonds Ionic and metallic Covalent and ionic vdW and hydrogen metallic and covalent
Covalent and ionic
What type(s) of bonding would be expected for rubber? Van der Waals bonding Covalent bonding with some van der Waals bonding Ionic bonding Metallic bonding
Covalent bonding with some van der Waals bonding
Solids comprised of organic polymers usually have the following types of bonds Covalent, ionic, dipolar, hydrogen, and VdW Covalent and metallic Ionic and metallic Mainly VdW
Covalent, ionic, dipolar, hydrogen, and VdW
Elastic Modulus is proportional to which of the following characteristics of the interatomic potential vs distance curve Minimum value of potential energy First derivative of potential energy at minimum Curvature of potential energy at minimum Skewness of potential energy at minimum
Curvature of potential energy at minimum
For a liquid to solid transformation, the critical nucleus size required for particle growth Depends upon only the change in volume free energy Depends upon the volume free energy and surface energy Is not a function of the degree of supercooling of the liquid Is generally greater for heterogeneous surfaces
Depends upon the volume free energy and surface energy
When h+k+l is odd for BCC crystals no diffraction occurs from the (hkl) plane: Due to an in-plane shift in the atomic arrangements between two adjacent (hkl) planes Due to the presence of an extra plane of atoms between two adjacent (hkl) planes Because Bragg's diffraction condition is never satisfied. None of the above
Due to the presence of an extra plane of atoms between two adjacent (hkl) planes
From the atomistic point of view elastic deformation occurs: Due to a shearing between atomic planes. Due to the slipping of an edge dislocation Due to a change in the atomic size of radius Due to the stretching or compression of inter-atomic bonds
Due to the stretching or compression of inter-atomic bonds
Heterogeneous Nucleation requires Impurities Surfaces Gas Either Impurities or Surfaces
Either Impurities or Surfaces
Elements on the right side of the periodic table Electropositive Alkaline earth metals Electronegative None of the above
Electronegative
The most ductile microstructure of steel is Ferrite Pearlite Bainite Martensite
Ferrite
For most metals, the relationship between elastic and shear moduli is approximately which of the following? G = 0.1 E G = 0.2 E G = 0.3 E G = 0.4 E G = 0.5 E
G = 0.4 E
Select the correct statement about grain boundaries Grain boundaries lower the free energy of metals Grain boundaries define crystal structure orientation differences from crystal to crystal Grain boundaries generally increase the ductility of polycrystals In any given metal, all grain boundaries are equivalent
Grain boundaries define crystal structure orientation differences from crystal to crystal
Which of the following material characteristics leads to high fracture toughness Large crack lengths High modulus of elasticity Low specific surface energy High Poisson's ratio
High modulus of elasticity
For a particular crystal structure, the slip direction is that direction in the slip plane having the highest linear density. lowest linear density.
Highest linear density
How would the plane strain fracture toughness of a metal be expected to change with rising temperature? Decrease Increase Remain constant
Increase
The diffusion coefficient in crystalline solids Increases with temperature linearly Increases with temperature quadradically Increases with temperature exponentially Is not a function of temperature
Increases with temperature exponentially
Which of the following factor(s) favor(s) brittle fracture in polymers? Increasing in temperature. Increasing in strain rate. The presence of a sharp notch. Decreasing specimen thickness.
Increasing in strain rate and the presence of a sharp notch
Diffusion by which mechanism occurs more rapidly in metal alloys? Interstitial diffusion Vacancy diffusion
Interstitial diffusion
Hydrocarbon compounds with the same composition but different atomic arrangements are called Isomers Polymorphs Polymers Aromatic hydrocarbons
Isomers
In order for a polymer to behave as an elastomer, which of the following are necessary? It must not crystallize easily; chain bond rotations must be relatively free; the polymer must be above its glass transition temperature. It must not crystallize easily; chain bond rotations must not be relatively free; the polymer must be below its glass transition temperature. It must not crystallize easily; chain bond rotations must be relatively free; the polymer must be below its glass transition temperature. It must not crystallize easily; chain bond rotations must not be relatively free; the polymer must be above its glass transition temperature.
It must not crystallize easily; chain bond rotations must be relatively free; the polymer must be above its glass transition temperature
The melting point of a solid correlates most to which of the following attributes Bond Length Bond Angle Bond Unharmonicity Bond Strength
Bond Strength
Which of the following factors may influence the corrosion rates of materials? Fluid composition Temperature Fluid velocity All of the Above
All of the Above
Once a system is at a state of equilibrium, a shift from equilibrium may result by alteration of which of the following? Pressure Composition Temperature All of the above
All of the above
The charge carriers in ionic ceramics can be electrons holes anions cations all the above
All of the above
Which of the following PVC materials is likely to have the lowest tensile strength Atactic with molecular weight 100 kg/mol Atactic with molecular weight 200 kg/mol Isotactic with molecular weight 100 kg/mol Isotactic with molecular weight 200 kg/mol
Atactic with molecular weight 100 kg/mol
What is the difference between atomic mass and atomic weight? Atomic mass is characterized by the number of neutrons in the nucleus, whereas atomic weight is the weight of an individual atom. Atomic mass is the mass of an individual atom, whereas atomic weight is the average (weighted) of the atomic masses of an atom's naturally occurring isotopes. Atomic mass is the average of the atomic masses of an atom's naturally occurring isotopes, whereas atomic weight is the weight of an individual atom. Atomic weight = Atomic mass × g. Atomic mass is characterized by the number of protons in the nucleus, whereas atomic weight is the average (weighted) of the atomic masses of an atom's naturally occurring isotopes.
Atomic mass is the mass of an individual atom, whereas atomic weight is the average (weighted) of the atomic masses of an atom's naturally occurring isotopes
Which of the following transformations cannot occur in the Fe-C system during an isothermal heat treatment Austenite to Pearlite Bainite to Martensite Austenite to Bainite Martensite to tempered Martensite
Bainite to Martensite
