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Chemistry
Q:
Which of these elements is likely to be found in nature as a free metal?
A) element A
B) element B
C) element C
D) element D
Q:
Look at the location of elements A, B, C, and D in the following periodic table.Which of these elements is likely to be found in nature as a carbonate?A) element AB) element BC) element CD) element D
Q:
Relative to a bulk sample of gold, nanoparticles of gold haveA) greater reactivity and higher melting point.B) greater reactivity and lower melting point.C) lower reactivity and higher melting point.D) lower reactivity and lower melting point.
Q:
Silicon nitride/zirconia is a example of a
A) ceramic-ceramic composite.
B) ceramic-metal composite.
C) ceramic-polymer composite.
D) superconductor.
Q:
What is a cermet?
A) boron nitride/epoxy
B) ceramic-metal composite
C) ceramic-polymer composite
D) silicon carbide/graphite
Q:
Silica (SiO2) can be prepared from silicon ethoxide by the sol-gel process. Write a balanced equation for the hydrolysis of silicon ethoxide.A) SiCl4 + 4 HOCH2CH3 + 4 NH3 -> Si(OCH2CH3)4 + 4 NH4Cl (in benzene)B) Si(OCH2CH3)4 + 4 H2O -> Si(OH)4 + 4 HOCH2CH3C) Si(OCH2CH3)4 + 4 HOCH3 -> Si(OCH3)4 + 4 HOCH2CH3D) Si(OCH3)4 + 4 H2O -> Si(OH)4 + 4 HOCH3
Q:
What is not part of the sol-gel process for the production of titania?A) TiCl4 + 4 HOCH2CH3 + 4 NH3 -> Ti(OCH2CH3)4 + 4 NH4Cl (in benzene)B) Ti(OCH2CH3)4 + 4 H2O -> Ti(OH)4 + 4 HOCH2CH3C) (HO)3-Ti-OH + HO-Ti-(OH)3 -> (HO)3-Ti-O-Ti(OH)3 + H2OD) 4 Ti(OH)4 + heat -> 2 Ti2O3 + 8 H2O + O2
Q:
What is the sol-gel process?
A) a series of chemical steps that involves the isolation of CuS and then roasting with oxygen
B) a series of chemical steps that involves the isolation of SO3 and then treatment with H2SO4
C) a series of chemical steps that involves the synthesis of a metal oxide powder from a metal alkoxide
D) a series of chemical steps that involves the thermal decomposition of fibers of polyacrylonitrile
Q:
What is the coordination number of Si in SiC that has a diamond-like structure?
A) 1
B) 2
C) 4
D) 6
Q:
What is not generally considered to be a ceramic?
A) indium, In
B) silica, SiO2
C) silicon nitride, Si3N4
D) zirconia, ZiO2
Q:
What is the name of the oxide ceramic BeO?
A) beryllia
B) beryllic
C) beryllium ceramic
D) beryllium oxide
Q:
What substance has a rating of 10 on the Mohs hardness scale?
A) alumina
B) aluminum
C) diamond
D) talc
Q:
Why are ceramics so much more brittle than metals?
A) The bonding in ceramics has a very high degree of ionic bonding character.
B) The bonding in ceramics has a very high degree of pi bonding character.
C) The bonding in ceramics is highly nondirectional.
D) The localized bonding in ceramics is highly directional.
Q:
Sintering is
A) a filtration process through a molecular sieve.
B) the process of heating particles of a powder below the melting point so that they fuse together.
C) the process of rapid cooling of a material to yield a superconducting mixture.
D) the process of removing metals from ore by passing material through a magnetic field.
Q:
Which process is used in the fabrication of ceramics?
A) electrolysis
B) reduction
C) roasting
D) sintering
Q:
Why are ceramics superior to metals as structural materials?
A) Ceramics are easier to fabricate into shapes than metals.
B) Ceramics are more malleable than metals.
C) Ceramics are more resistant to wear and corrosion than metals.
D) Ceramics have greater impact resistance than metals.
Q:
Which has been found to be a three dimensional superconductor that conducts equally in all directions?
A) C (diamond)
B) C (graphite)
C) K3C60
D) YBa2Cu3O7
Q:
What structural features appear necessary for superconductivity in the 1-2-3 YBa2Cu3O7 superconductor?
A) high metallic character.
B) infinite extended layers of Cu and O atoms and a fractional oxidation state for Cu
C) presence of an inner transition element
D) all of the above statements
Q:
What is the Meissner effect associated with superconductors?
A) when the temperature above which the superconductor fails to work
B) when the temperature at which the superconductors become perfect insulators
C) when the net magnetic field within the bulk of the superconductor is zero
D) when the net magnetic field within the bulk of the superconductor becomes nearly infinite
Q:
Below the superconducting transition temperature Tc, superconductors
A) become perfect conductors.
B) become perfect magnets.
C) become perfect resistors.
D) fail to work.
Q:
What element was found to be the first superconductor of electricity at 4.2 K in 1911?
A) copper
B) iron
C) gallium
D) mercury
Q:
Who discovered the phenomenon of superconductivity in 1911?
A) J. G. Bednorz
B) R. B. Fuller
C) K. A. Mller
D) H. K. Onnes
Q:
What is the average oxidation number of Cu in the 1-2-3 superconductor YBa2Cu3O7 if Y is in the +3 oxidation state?
A) +2
B) +2.33
C) +3
D) +3.33
Q:
What is the average oxidation state of Cu in HgCa2Ba2Cu3O8-x if Hg is in the +2 oxidation state?
A) +1
B) +2
C) -2 - 2x/3
D) +2 + 2x/3
Q:
A particular superconductor has eight copper atoms on corners and eight copper atoms on edges of its unit cell. How many copper atoms are attributed to a single unit cell of this superconductor?
A) 1
B) 3
C) 5
D) 16
Q:
Which one of the following is a metallic conductor at room temperature but a superconductor at 18 K?
A) diamond
B) graphite
C) fullerene
D) potassium fulleride
Q:
A light emitting diode with a band gap of 181 kJ/mol emits light in what region of the electromagnetic radiation spectrum?
A) infrared
B) ultraviolet
C) visible - blue
D) visible - red
Q:
Photovoltaic cells use light to
A) excite electrons into the conduction band of a n-type semiconductor.
B) excite electrons into the conduction band of a p-type semiconductor.
C) excite holes into the conduction band of a n-type semiconductor.
D) excite electrons into the valence band of a p-type semiconductor.
Q:
Which statement about a diode laser is false?
A) Light is emitted when a reverse bias is applied to the p-n junction.
B) Electrons and holes recombine at the p-n junction.
C) A laser cavity reflects the emitted light back and forth to provide stimulated emission.
D) The light emerging from the laser possesses geat intensity, a single frequency, and a single phase.
Q:
Which combination of semiconductors can be employed to make a diode?
A) GaAs doped with Ge and GaP doped with Si
B) GaAs doped with Se and GaP doped with Zn
C) Si doped with B and Ge doped with Ga
D) Si doped with P and Ge doped with As
Q:
Which one of the following is a p-type of semiconductor?
A) germanium doped with antimony
B) germanium doped with boron
C) tellurium
D) YBa2Cu3O7
Q:
Which one of the following is an n-type of semiconductor?
A) alumina
B) germanium doped with antimony
C) germanium doped with boron
D) tellurium
Q:
How would one classify a silicon crystal doped with indium?
A) conductor
B) n-type semiconductor
C) p-type semiconductor
D) insulator
Q:
How would one classify copper mixed with tin?
A) conductor
B) n-type semiconductor
C) p-type semiconductor
D) insulator
Q:
How would one classify a germanium crystal doped with arsenic?
A) conductor
B) n-type semiconductor
C) p-type semiconductor
D) insulator
Q:
Which element has the smallest energy band gap?
A) C (diamond)
B) Ge
C) Pb
D) Si
Q:
Which element has the largest energy band gap?
A) C (diamond)
B) Si
C) Ge
D) Sn (white)
Q:
Which substance has a larger band gap than silicon?
A) diamond
B) copper
C) germanium
D) silver
Q:
Which substance is a good semiconductor?
A) diamond
B) germanium
C) gold
D) phosphorus
Q:
Which one of the following is an electrical insulator?
A) alumina
B) germanium doped with antimony
C) gold
D) tellurium
Q:
Which of the following is a semiconductor?
A) Al
B) B
C) Ga
D) Pb
Q:
White tin has an electrical conductivity that decreases with increasing temperature, and gray tin has an electrical conductivity that increases with increasing temperature. Therefore, white tin is classified as a(n) ________, and gray tin is classified as a(n) ________.
A) insulator, metal
B) metal, insulator
C) metal, semiconductor
D) semiconductor, metal
Q:
What type of substances exhibit an increase in conductivity with an increase in temperature?
A) both metals and semiconductors
B) only insulators
C) only metals
D) only semiconductors
Q:
Electrical resistance of a metal ________ with increasing temperature.
A) can decrease or increase
B) decreases
C) does not change
D) increases
Q:
Which one of the following metals is expected to have the highest melting point?
A) Cd
B) Cr
C) Hg
D) Zn
Q:
Metals are good conductors of heat because
A) the valence electrons are free to move about the crystal lattice.
B) heat is carried as kinetic energy by rapid vibrations from atom to atom in the crystal lattice.
C) metal cations in the crystal are efficient at transporting heat.
D) holes are created in the crystal lattice as electrons enter the conduction band and the holes conduct the heat while electrons conduct electrical charge.
Q:
Which substance is the best conductor of electricity?
A) diamond
B) germanium
C) gold
D) phosphorus
Q:
Which of the following is the softest and most maleable?
A) Cu
B) V
C) Ru
D) Mn
Q:
Which metal has maximum filling of bonding molecular orbitals and minimal filling of antibonding molecular orbitals in its composite s-d band?
A) Au
B) Cs
C) Re
D) W
Q:
What terminology best describes the bonding in the following schematic of a metal? A) ionic bonding
B) covalent bonding
C) electron-sea model
D) crystal model
Q:
To three significant figures, how many metric tons of iron ore are needed to produce 10,000 metric tons of iron per day in the blast furnace process? Assume that the iron ore is iron(III) oxide and that the ore is 70.0% pure. The reaction of interest is A) 14,300 metric tons
B) 20,000 metric tons
C) 20,400 metric tons
D) 30,000 metric tons
Q:
In the reaction shown below calcium phosphate slag is formed from a reaction of calcium oxide with phosphoric anhydride.6 CaO(s) + P4O10(l) -> 2 Ca3(PO4)2(l)CaO is a(n) ________ oxide, and P4O10 is a(n) ________ oxide.A) acidic, acidicB) acidic, basicC) basic, acidicD) basic, basic
Q:
What is not a major component of slag?
A) CaSiO3
B) Ca3(PO4)2
C) Fe2O3
D) MnSiO3
Q:
What is not a primary ingredient used in the production of iron by the blast furnace process?
A) coke
B) iron ore
C) limestone
D) phosphates and silicates
Q:
Why is silicon dioxide added to molten iron in the basic oxygen process?
A) to remove acidic oxides from the molten iron
B) to remove manganese oxide from the molten iron
C) to remove phosphates and carbonates from the molten iron
D) to remove trace amounts of carbon from the molten iron
Q:
Why is CaCO3 added to a blast furnace in the steel making process?
A) to give a source of CO2
B) to remove basic oxides from the iron ore
C) to remove silicates from the iron ore
D) to remove unreactive carbon from the iron ore
Q:
Steel is a mixture composed primarily of
A) iron and carbon.
B) iron and copper.
C) iron and silicon.
D) iron and sulfur.
Q:
Zinc occurs in sulfide ores. How many liters of SO2(g) are produced at STP for each kilogram of roasted ore that is 70% zinc sulfide?
A) 160 L
B) 230 L
C) 460 L
D) 660 L
Q:
What conditions favor the decomposition of Ni(CO)4 into Ni and CO after equilibrium is established in the reaction that has both ΔH and ΔS being negative?
A) decrease volume
B) increase pressure
C) increase temperature
D) simultaneously increase the pressure and decrease volume
Q:
What is the chemical process most likely to be used to purify zirconium metal?
A) distillation
B) electrorefining
C) reaction with carbon monoxide (a Mond process)
D) reaction with iodine
Q:
What is the chemical process most likely to be used to purify nickel metal?
A) distillation
B) electrorefining
C) reaction with carbon monoxide (a Mond process)
D) reaction with iodine
Q:
Which element is likely to be a principal impurity in zinc ore?
A) cadmium
B) copper
C) gallium
D) nickel
Q:
Which of the following metals is not commonly obtained by electrolysis?
A) Al
B) Li
C) Na
D) Zn
Q:
How does one commercially reduce the metal oxides or chlorides of sodium and magnesium?
A) electrolysis of the molten salts
B) high temperature reduction with aluminum
C) high temperature reduction with carbon
D) roasting
Q:
What is not an appropriate method of isolating the metals shown?A) HgS(s) + O2(g) + heat -> Hg(g) + SO2(g)B) ZnO(s) + C(s) + heat -> Zn(g) + CO(g)C) WO3(s) + 3 H2(g) + heat -> W(s) + 3 H2O(g)D) Al2O3(s) + 2 Cr(s) + heat -> Cr2O3(s) + 2 Al(l)
Q:
When zinc sulfide undergoes roasting, the products are
A) Zn and S.
B) Zn and H2S.
C) ZnO and S.
D) ZnO and SO2.
Q:
The chemical process of roasting is commonly used to facilitate the reduction of which metal ores?
A) Ag, Cu, and Hg
B) Al, Mg, and Na
C) Au and Pt
D) Fe, Mn, and V
Q:
What is the name of the process commonly associated with the isolation and concentration of Al2O3 from the ore bauxite (Al2O3 xH2O)?
A) basic oxygen process
B) bayer process
C) contact process
D) mond process
Q:
How is slag separated from molten ore in a blast furnace?
A) chemical treatment
B) density differences
C) distillation
D) magnetic differences
Q:
What is the concentration process used to separate chalcopyrite (CuFeS2) from its gangue?
A) chemical treatment
B) density differences
C) floatation process
D) magnetic differences
Q:
Which of the following steps is not always necessary in the extraction of a metal from its ore?
A) chemical treatment prior to reduction
B) concentration of the ore
C) reduction of the mineral to the free metal
D) refining or purification of the metal
Q:
What is not a metallurgy process?
A) environmental reconstruction of the landscape
B) extraction of metals from their ores
C) making of alloys and metallic composites
D) reduction of the mineral to the free metal
Q:
Which of the following elements is most likely to naturally occur as a carbonate?
A) Ca
B) Co
C) Cr
D) Cu
Q:
Which of the following elements is most likely to occur as a metal sulfide ore?
A) Hf
B) Hg
C) K
D) W
Q:
Which substance is commonly found in nature in an uncombined form?
A) aluminum
B) iron
C) platinum
D) tin
Q:
Which of the following metals occurs in nature principally as oxide ores?
A) Ca
B) Co
C) Cr
D) Cu
Q:
What statement is inconsistent concerning the correlation of the chemical compositions of the most common ores with the locations of their metals in the periodic table?
A) Gold and the platinum-group metals (Ru, Os, Rh, Ir, Pd, and Pt) are sufficiently unreactive to occur commonly as the free metals.
B) The early transition metals on the left side of the d block generally occur as oxides while the more electronegative, late transition metals on the right side of the d block occur as sulfides.
C) The more electronegative p-block metals are commonly found as oxides and nitrates except for Al and Sn which are found as sulfides.
D) The s-block metals are found in nature as carbonates, silicates and in the case of Na and K as chlorides.
Q:
What metal is isolated from the ore rutile and what is the chemical formula of rutile?
A) aluminum, Al2O3 xH2O
B) manganese, MnO2
C) tin, SnO2
D) titanium, TiO2
Q:
What metal is isolated from the ore sphalerite?
A) copper
B) manganese
C) titanium
D) zinc
Q:
What metal is isolated from the ore galena?
A) lead
B) manganese
C) tin
D) zinc