Chapter 21 Review Questions

General Chemistry: Atoms First, 2e (McMurry and Fay)Chapter 21 Metals and Solid-State Materials

21.1 Multiple Choice Questions

1) What are the most abundant minerals in the earth's crust?A) aluminosilicates and silicatesB) chlorides and iodidesC) nitrates and phosphatesD) oxides and sulfidesAnswer: ADiff: 1Topic: Section 21.1 Sources of the Metallic Elements

2) What minerals are important commercial sources of metals?A) aluminosilicates and silicatesB) chlorides and iodidesC) nitrates and phosphatesD) oxides and sulfidesAnswer: DDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

3) What is a principal commercial ore for the element aluminum?A) bauxiteB) chalcopyriteC) chromiteD) hematiteAnswer: ADiff: 1Topic: Section 21.1 Sources of the Metallic Elements

4) What is a principal commercial ore for the element iron?A) cassiteriteB) cinnabarC) galenaD) hematiteAnswer: DDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

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5) What is the most important copper containing ore? A) cassitriteB) chalcopyriteC) chromiteD) cinnabarAnswer: BDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

6) What metal is isolated from the ore galena?A) leadB) manganeseC) tinD) zincAnswer: ADiff: 1Topic: Section 21.1 Sources of the Metallic Elements

7) What metal is isolated from the ore sphalerite?A) copperB) manganeseC) titaniumD) zincAnswer: DDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

8) What metal is isolated from the ore rutile and what is the chemical formula of rutile?A) aluminum, Al2O3 ∙ xH2OB) manganese, MnO2C) tin, SnO2D) titanium, TiO2Answer: DDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

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9) 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.Answer: CDiff: 2Topic: Section 21.1 Sources of the Metallic Elements

10) Which of the following metals occurs in nature principally as oxide ores?A) CaB) CoC) CrD) CuAnswer: CDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

11) Which substance is commonly found in nature in an uncombined form?A) aluminumB) ironC) platinumD) tinAnswer: CDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

12) Which of the following elements is most likely to occur as a metal sulfide ore?A) HfB) HgC) KD) WAnswer: BDiff: 1Topic: Section 21.1 Sources of the Metallic Elements

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13) Which of the following elements is most likely to naturally occur as a carbonate?A) CaB) CoC) CrD) CuAnswer: ADiff: 1Topic: Section 21.1 Sources of the Metallic Elements

14) What is not a metallurgy process?A) environmental reconstruction of the landscapeB) extraction of metals from their oresC) making of alloys and metallic compositesD) reduction of the mineral to the free metalAnswer: ADiff: 1Topic: Section 21.2 Metallurgy

15) Which of the following steps is not always necessary in the extraction of a metal from its ore?A) chemical treatment prior to reductionB) concentration of the oreC) reduction of the mineral to the free metalD) refining or purification of the metalAnswer: ADiff: 1Topic: Section 21.2 Metallurgy

16) What is the concentration process used to separate chalcopyrite (CuFeS2) from its gangue?A) chemical treatmentB) density differencesC) floatation processD) magnetic differencesAnswer: CDiff: 1Topic: Section 21.2 Metallurgy

17) How is slag separated from molten ore in a blast furnace?A) chemical treatmentB) density differencesC) distillationD) magnetic differencesAnswer: BDiff: 1Topic: Section 21.2 Metallurgy

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18) 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 processB) bayer processC) contact processD) mond processAnswer: BDiff: 1Topic: Section 21.2 Metallurgy

19) The chemical process of roasting is commonly used to facilitate the reduction of which metal ores?A) Ag, Cu, and HgB) Al, Mg, and NaC) Au and PtD) Fe, Mn, and VAnswer: ADiff: 1Topic: Section 21.2 Metallurgy

20) When zinc sulfide undergoes roasting, the products areA) Zn and S.B) Zn and H2S.C) ZnO and S.D) ZnO and SO2.Answer: DDiff: 1Topic: Section 21.2 Metallurgy

21) 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)Answer: DDiff: 1Topic: Section 21.2 Metallurgy

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22) How does one commercially reduce the metal oxides or chlorides of sodium and magnesium?A) electrolysis of the molten saltsB) high temperature reduction with aluminumC) high temperature reduction with carbonD) roastingAnswer: ADiff: 1Topic: Section 21.2 Metallurgy

23) Which of the following metals is not commonly obtained by electrolysis?A) AlB) LiC) NaD) ZnAnswer: DDiff: 1Topic: Section 21.2 Metallurgy

24) Which element is likely to be a principal impurity in zinc ore?A) cadmiumB) copperC) galliumD) nickelAnswer: ADiff: 1Topic: Section 21.2 Metallurgy

25) What is the chemical process most likely to be used to purify nickel metal?A) distillationB) electrorefining C) reaction with carbon monoxide (a Mond process)D) reaction with iodineAnswer: CDiff: 1Topic: Section 21.2 Metallurgy

26) What is the chemical process most likely to be used to purify zirconium metal?A) distillationB) electrorefining C) reaction with carbon monoxide (a Mond process)D) reaction with iodineAnswer: DDiff: 1Topic: Section 21.2 Metallurgy

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27) 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 volumeB) increase pressureC) increase temperatureD) simultaneously increase the pressure and decrease volumeAnswer: CDiff: 1Topic: Section 21.2 Metallurgy

28) 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 LB) 230 LC) 460 LD) 660 LAnswer: ADiff: 2Topic: Section 21.2 Metallurgy

29) Steel is a mixture composed primarily of A) iron and carbon.B) iron and copper.C) iron and silicon.D) iron and sulfur.Answer: ADiff: 1Topic: Section 21.3 Iron and Steel

30) Why is CaCO3 added to a blast furnace in the steel making process?A) to give a source of CO2B) to remove basic oxides from the iron oreC) to remove silicates from the iron oreD) to remove unreactive carbon from the iron oreAnswer: CDiff: 2Topic: Section 21.3 Iron and Steel

31) Why is silicon dioxide added to molten iron in the basic oxygen process?A) to remove acidic oxides from the molten ironB) to remove manganese oxide from the molten ironC) to remove phosphates and carbonates from the molten ironD) to remove trace amounts of carbon from the molten ironAnswer: BDiff: 2Topic: Section 21.3 Iron and Steel

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32) What is not a primary ingredient used in the production of iron by the blast furnace process?A) cokeB) iron oreC) limestoneD) phosphates and silicatesAnswer: DDiff: 1Topic: Section 21.3 Iron and Steel

33) What is not a major component of slag?A) CaSiO3B) Ca3(PO4)2C) Fe2O3D) MnSiO3Answer: CDiff: 2Topic: Section 21.3 Iron and Steel

34) 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, basicAnswer: CDiff: 1Topic: Section 21.3 Iron and Steel

35) 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 tonsB) 20,000 metric tonsC) 20,400 metric tonsD) 30,000 metric tonsAnswer: CDiff: 2Topic: Section 21.3 Iron and Steel

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36) What terminology best describes the bonding in the following schematic of a metal?

A) ionic bondingB) covalent bondingC) electron-sea modelD) crystal modelAnswer: CDiff: 1Topic: Section 21.4 Bonding in Metals

37) Which metal has maximum filling of bonding molecular orbitals and minimal filling of antibonding molecular orbitals in its composite s-d band?A) AuB) CsC) ReD) WAnswer: DDiff: 3Topic: Section 21.4 Bonding in Metals

38) Which of the following is the softest and most maleable?A) CuB) VC) RuD) MnAnswer: ADiff: 3Topic: Section 21.4 Bonding in Metals

39) Which substance is the best conductor of electricity?A) diamondB) germaniumC) goldD) phosphorusAnswer: CDiff: 1Topic: Section 21.4 Bonding in MetalsAlgo. Option: algorithmic

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40) Metals are good conductors of heat becauseA) 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.Answer: ADiff: 2Topic: Section 21.4 Bonding in Metals

41) Which one of the following metals is expected to have the highest melting point?A) CdB) CrC) HgD) ZnAnswer: BDiff: 3Topic: Section 21.4 Bonding in MetalsAlgo. Option: algorithmic

42) Electrical resistance of a metal ________ with increasing temperature.A) can decrease or increaseB) decreasesC) does not changeD) increasesAnswer: DDiff: 1Topic: Section 21.4 Bonding in Metals

43) What type of substances exhibit an increase in conductivity with an increase in temperature?A) both metals and semiconductorsB) only insulatorsC) only metalsD) only semiconductorsAnswer: DDiff: 1Topic: Section 21.5 Semiconductors

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44) 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, metalB) metal, insulatorC) metal, semiconductorD) semiconductor, metalAnswer: CDiff: 1Topic: Section 21.5 Semiconductors

45) Which of the following is a semiconductor?A) AlB) BC) GaD) PbAnswer: BDiff: 1Topic: Section 21.5 Semiconductors

46) Which one of the following is an electrical insulator?A) aluminaB) germanium doped with antimonyC) goldD) telluriumAnswer: ADiff: 2Topic: Section 21.5 SemiconductorsAlgo. Option: algorithmic

47) Which substance is a good semiconductor?A) diamondB) germaniumC) goldD) phosphorusAnswer: BDiff: 1Topic: Section 21.5 Semiconductors

48) Which substance has a larger band gap than silicon?A) diamondB) copperC) germaniumD) silverAnswer: ADiff: 1Topic: Section 21.5 Semiconductors

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49) Which element has the largest energy band gap?A) C (diamond)B) SiC) GeD) Sn (white)Answer: ADiff: 1Topic: Section 21.5 Semiconductors

50) Which element has the smallest energy band gap?A) C (diamond)B) GeC) PbD) SiAnswer: CDiff: 1Topic: Section 21.5 SemiconductorsAlgo. Option: algorithmic

51) How would one classify a germanium crystal doped with arsenic? A) conductorB) n-type semiconductorC) p-type semiconductorD) insulatorAnswer: BDiff: 1Topic: Section 21.5 Semiconductors

52) How would one classify copper mixed with tin?A) conductorB) n-type semiconductorC) p-type semiconductorD) insulatorAnswer: ADiff: 2Topic: Section 21.5 Semiconductors

53) How would one classify a silicon crystal doped with indium?A) conductorB) n-type semiconductorC) p-type semiconductorD) insulatorAnswer: CDiff: 1Topic: Section 21.5 Semiconductors

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54) Which one of the following is an n-type of semiconductor?A) aluminaB) germanium doped with antimonyC) germanium doped with boronD) telluriumAnswer: BDiff: 1Topic: Section 21.5 Semiconductors

55) Which one of the following is a p-type of semiconductor?A) germanium doped with antimonyB) germanium doped with boronC) telluriumD) YBa2Cu3O7Answer: BDiff: 1Topic: Section 21.5 Semiconductors

56) Which combination of semiconductors can be employed to make a diode?A) GaAs doped with Ge and GaP doped with SiB) GaAs doped with Se and GaP doped with ZnC) Si doped with B and Ge doped with GaD) Si doped with P and Ge doped with AsAnswer: BDiff: 4Topic: Section 21.6 Semiconductor Applications

57) 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.Answer: ADiff: 2Topic: Section 21.6 Semiconductor Applications

58) 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.Answer: ADiff: 2Topic: Section 21.6 Semiconductor Applications

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59) A light emitting diode with a band gap of 181 kJ/mol emits light in what region of the electromagnetic radiation spectrum?A) infraredB) ultravioletC) visible - blueD) visible - redAnswer: DDiff: 1Topic: Section 21.6 Semiconductor Applications

60) Which one of the following is a metallic conductor at room temperature but a superconductor at 18 K?A) diamondB) graphiteC) fullereneD) potassium fullerideAnswer: DDiff: 1Topic: Section 21.7 Superconductors

61) 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) 1B) 3C) 5D) 16Answer: BDiff: 1Topic: Section 21.7 Superconductors

62) What is the average oxidation state of Cu in HgCa2Ba2Cu3O8-x if Hg is in the +2 oxidation state?A) +1B) +2C) -2 - 2x/3D) +2 + 2x/3Answer: CDiff: 4Topic: Section 21.7 Superconductors

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63) What is the average oxidation number of Cu in the 1-2-3 superconductor YBa2Cu3O7 if Y is in the +3 oxidation state?A) +2B) +2.33C) +3D) +3.33Answer: BDiff: 3Topic: Section 21.7 Superconductors

64) Who discovered the phenomenon of superconductivity in 1911?A) J. G. BednorzB) R. B. FullerC) K. A. M llerD) H. K. OnnesAnswer: DDiff: 1Topic: Section 21.7 Superconductors

65) What element was found to be the first superconductor of electricity at 4.2 K in 1911?A) copperB) ironC) galliumD) mercuryAnswer: DDiff: 1Topic: Section 21.7 Superconductors

66) Below the superconducting transition temperature Tc, superconductors A) become perfect conductors.B) become perfect magnets.C) become perfect resistors.D) fail to work.Answer: ADiff: 1Topic: Section 21.7 Superconductors

67) What is the Meissner effect associated with superconductors? A) when the temperature above which the superconductor fails to workB) when the temperature at which the superconductors become perfect insulatorsC) when the net magnetic field within the bulk of the superconductor is zeroD) when the net magnetic field within the bulk of the superconductor becomes nearly infiniteAnswer: CDiff: 1Topic: Section 21.7 Superconductors

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68) 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 CuC) presence of an inner transition elementD) all of the above statementsAnswer: BDiff: 2Topic: Section 21.7 Superconductors

69) Which has been found to be a three dimensional superconductor that conducts equally in all directions?A) C (diamond)B) C (graphite)C) K3C60D) YBa2Cu3O7Answer: CDiff: 2Topic: Section 21.7 Superconductors

70) 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.Answer: CDiff: 1Topic: Section 21.8 Ceramics

71) Which process is used in the fabrication of ceramics?A) electrolysisB) reductionC) roastingD) sinteringAnswer: DDiff: 1Topic: Section 21.8 Ceramics

72) Sintering isA) 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.Answer: BDiff: 1Topic: Section 21.8 Ceramics

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73) 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.Answer: DDiff: 2Topic: Section 21.8 Ceramics

74) What substance has a rating of 10 on the Mohs hardness scale?A) aluminaB) aluminumC) diamondD) talcAnswer: CDiff: 1Topic: Section 21.8 Ceramics

75) What is the name of the oxide ceramic BeO?A) berylliaB) beryllicC) beryllium ceramicD) beryllium oxideAnswer: ADiff: 1Topic: Section 21.8 Ceramics

76) What is not generally considered to be a ceramic?A) indium, InB) silica, SiO2C) silicon nitride, Si3N4 D) zirconia, ZiO2Answer: ADiff: 1Topic: Section 21.8 Ceramics

77) What is the coordination number of Si in SiC that has a diamond-like structure?A) 1B) 2C) 4D) 6Answer: CDiff: 2Topic: Section 21.8 Ceramics

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78) What is the sol-gel process?A) a series of chemical steps that involves the isolation of CuS and then roasting with oxygenB) a series of chemical steps that involves the isolation of SO3 and then treatment with H2SO4C) a series of chemical steps that involves the synthesis of a metal oxide powder from a metal alkoxideD) a series of chemical steps that involves the thermal decomposition of fibers of polyacrylonitrileAnswer: CDiff: 1Topic: Section 21.8 Ceramics

79) 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 + O2Answer: DDiff: 2Topic: Section 21.8 Ceramics

80) 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 HOCH3Answer: BDiff: 2Topic: Section 21.8 Ceramics

81) What is a cermet?A) boron nitride/epoxyB) ceramic-metal compositeC) ceramic-polymer compositeD) silicon carbide/graphiteAnswer: BDiff: 1Topic: Section 21.9 Composites

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82) Silicon nitride/zirconia is a example of aA) ceramic-ceramic composite.B) ceramic-metal composite.C) ceramic-polymer composite.D) superconductor.Answer: ADiff: 2Topic: Section 21.9 Composites

83) 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.Answer: BDiff: 1Topic: FYI Will the Next Big Thing Be Really Small?

Look at the location of elements A, B, C, and D in the following periodic table.

84) Which of these elements is likely to be found in nature as a carbonate?A) element AB) element BC) element CD) element DAnswer: ADiff: 1Topic: Conceptual Problems

85) Which of these elements is likely to be found in nature as a free metal?A) element AB) element BC) element CD) element DAnswer: CDiff: 1Topic: Conceptual Problems

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86) Which of these elements is likely to be found in nature as a sulfide?A) element AB) element BC) element CD) element DAnswer: DDiff: 1Topic: Conceptual Problems

87) Which of these elements is likely to be found in nature as an oxide?A) element AB) element BC) element CD) element DAnswer: BDiff: 1Topic: Conceptual Problems

88) Which of these elements is likely to be extracted from its ore by roasting of a metal sulfide?A) element AB) element BC) element CD) element DAnswer: DDiff: 1Topic: Conceptual Problems

89) Which of these elements is likely to be extracted from its ore by chemical reduction of a metal oxide?A) element AB) element BC) element CD) element DAnswer: BDiff: 1Topic: Conceptual Problems

90) Which of these elements is likely to be extracted from its ore by electrolysis?A) element AB) element BC) element CD) element DAnswer: ADiff: 1Topic: Conceptual Problems

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Use the picture below to answer the following questions.

91) What diagram would describe the molecular orbital picture for the species Na4?A) diagram (1)B) diagram (2)C) diagram (3)D) diagram (4)Answer: DDiff: 1Topic: Conceptual Problems

92) Which diagram describes the molecular orbital picture for the species Na6?A) diagram (4)B) diagram (5)C) diagram (6)D) diagram (7)Answer: CDiff: 1Topic: Conceptual Problems

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The following pictures show the electron population of the bands of MO energy levels for four different materials.

93) Which of these materials is an insulator?A) material (1)B) material (2)C) material (3)D) material (4)Answer: DDiff: 1Topic: Conceptual Problems

94) Which of these materials is a metal?A) material (1)B) material (2)C) material (3)D) material (4)Answer: ADiff: 1Topic: Conceptual Problems

95) Which of these materials is a semiconductor?A) materials (1) and (2)B) materials (1) and (4)C) materials (2) and (3)D) materials (3) and (4)Answer: CDiff: 1Topic: Conceptual Problems

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96) Which of these materials has the highest electrical conductivity?A) material (1)B) material (2)C) material (3)D) material (4)Answer: ADiff: 1Topic: Conceptual Problems

97) Which of these materials has the lowest electrical conductivity?A) material (1)B) material (2)C) material (3)D) material (4)Answer: DDiff: 1Topic: Conceptual Problems

98) Which of these materials has an electrical conductivity that increases with an increase in temperature?A) materials (1) and (2)B) materials (1) and (4)C) materials (2) and (3)D) materials (3) and (4)Answer: CDiff: 1Topic: Conceptual Problems

99) Which of these materials has an electrical conductivity that decreases with an increase in temperature?A) material (1)B) material (2)C) material (3)D) material (4)Answer: ADiff: 1Topic: Conceptual Problems

100) Which of these materials has an electrical conductivity that remains constant with an increase in temperature?A) material (1)B) material (2)C) material (3)D) material (4)Answer: DDiff: 1Topic: Conceptual Problems

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The following pictures show the electron populations of the composite s-d bands for four different transition metals.

101) Which metal has the highest melting point?A) metal (1)B) metal (2)C) metal (3)D) metal (4)Answer: CDiff: 3Topic: Conceptual Problems

102) Which metal has the lowest melting point?A) metal (1)B) metal (2)C) metal (3)D) metal (4)Answer: DDiff: 3Topic: Conceptual Problems

103) Which is the hardest metal?A) metal (1)B) metal (2)C) metal (3)D) metal (4)Answer: CDiff: 3Topic: Conceptual Problems

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The following pictures show the electron populations of the composite s-d bands for Sc, Ti, V, and Zn.

104) Which picture corresponds to Sc?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: ADiff: 1Topic: Conceptual Problems

105) Which picture corresponds to Ti?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: BDiff: 1Topic: Conceptual Problems

106) Which picture corresponds to V?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: CDiff: 1Topic: Conceptual Problems

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107) Which picture corresponds to Zn?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: DDiff: 1Topic: Conceptual Problems

The following pictures show the electron populations of the composite s - d bands for Y, Mo, Ag, and Cd.

108) Which picture corresponds to Y?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: ADiff: 1Topic: Conceptual Problems

109) Which picture corresponds to Mo?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: BDiff: 1Topic: Conceptual Problems

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110) Which picture corresponds to Ag?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: CDiff: 1Topic: Conceptual Problems

111) Which picture corresponds to Cd?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: DDiff: 1Topic: Conceptual Problems

The following picture shows the electron populations of the bands of MO energy levels for elementary silicon.

112) In this picture the band gap is given by letter(s)A) a.B) b.C) c.D) a and b.Answer: BDiff: 1Topic: Conceptual Problems

113) In this picture the conduction band is given by letter(s)A) a.B) b.C) c.D) a and b.Answer: ADiff: 1Topic: Conceptual Problems

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114) In this picture the valence band is given by letter(s)A) a.B) b.C) c.D) a and b.Answer: CDiff: 1Topic: Conceptual Problems

115) Which picture represents a p-type Si semiconductor?A) picture (A)B) picture (B)C) both picture (A) and picture (B)D) neither picture (A) nor picture (B)Answer: ADiff: 2Topic: Conceptual Problems

116) Which picture represents an n-type Si semiconductor?A) picture (A)B) picture (B)C) both picture (A) and picture (B)D) neither picture (A) nor picture (B)Answer: BDiff: 2Topic: Conceptual Problems

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Picture (1) shows the electron populations of the bands of MO energy levels for elementary silicon.

117) Which picture (1)-(4) shows the electron populations when the silicon is doped with gallium?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: CDiff: 2Topic: Conceptual Problems

118) Which picture (1)-(4) shows the electron populations when the silicon is doped with arsenic?A) picture (1)B) picture (2)C) picture (3)D) picture (4)Answer: BDiff: 2Topic: Conceptual Problems

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119) Which schematic best represents the electrical resistance versus temperature curve for a superconductor?

A) AB) BC) CD) none of theseAnswer: ADiff: 1Topic: Conceptual Problems

21.2 Algorithmic Questions

1) Which substance is the best conductor of electricity?A) arsenicB) boronC) silverD) telluriumAnswer: CDiff: 1Topic: Section 21.4 Bonding in MetalsAlgo. Option: algorithmic

2) Which one of the following metals is expected to have the highest melting point?A) LaB) NbC) HgD) PdAnswer: BDiff: 3Topic: Section 21.4 Bonding in MetalsAlgo. Option: algorithmic

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3) Which element has the smallest energy band gap?A) BB) IC) KD) SAnswer: CDiff: 2Topic: Section 21.5 SemiconductorsAlgo. Option: algorithmic

4) Which one of the following is an electrical insulator?A) phosphorusB) platinum C) potassiumD) rutheniumAnswer: ADiff: 2Topic: Section 21.5 SemiconductorsAlgo. Option: algorithmic

21.3 Short Answer Questions

1) The principal source of chromium is chromite, FeCr2O4 in which chromium has an oxidation state of ________ and iron has an oxidation state of ________.Answer: + 3, + 2Diff: 2Topic: Section 21.1 Sources of the Metallic Elements

2) The balanced chemical equation for the production of silver by roasting of its sulfide is ________.Answer: Ag2S(s) + O2(g) → 2 Ag(s) + SO2(g)Diff: 3Topic: Section 21.2 Metallurgy

3) During the production of iron, the formation of CaSiO3 (slag) from the reaction of CaO (lime) and SiO2 (sand), shown below, facilitates the separation of the iron from the gangue.

CaO(s) + SiO2(s) → CaSiO3(l) In this reaction the acidic oxide is ________ and the basic oxide is ________.Answer: SiO2, CaODiff: 2Topic: Section 21.3 Iron and Steel

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4) According to band theory, the element having all of its bonding molecular orbitals filled and all of its antibonding orbitals empty in the 4s-3d composite band is ________.Answer: CrDiff: 3Topic: Section 21.4 Bonding in Metals

5) Tin exists in two forms: gray tin and white tin. The electrical conductivity of gray tin increases with an increase in temperature, whereas the electrical conductivity of white tin decreases with an increase in temperature. The form of tin that is a semiconductor is ________ tin.Answer: grayDiff: 1Topic: Section 21.5 Semiconductors

6) Light emitting diodes (LEDs) used in automobile brake lights illuminate 200 milliseconds faster than conventional incandescent brake lights. The faster illumination gives the driver of a trailing car an additional stopping distance of ________ feet at 55 mph.Answer: 16Diff: 2Topic: Section 21.6 Semiconductor Applications

7) The wavelength of light emitted by the GaP0.40As0.60 LED, which has a band gap of 181 kJ/mol, is ________ nm.Answer: 661Diff: 4Topic: Section 21.6 Semiconductor Applications

8) Nonoxide ceramics include silicon nitride, the formula of which is ________.Answer: Si3N4Diff: 2Topic: Section 21.8 Ceramics

9) Composite materials can be classified as ceramic-ceramic, ceramic-metal, or ceramic-polymer. Boron nitride/epoxy is classified as ________.Answer: ceramic-polymer. Diff: 2Topic: Section 21.9 Composites

10) Because nanoparticles have a larger percentage of atoms on the surface of the nanoparticle than on the surface of bulk material, nanoparticles have ________ melting points and ________ chemical reactivity than the bulk material.Answer: lower, greaterDiff: 2Topic: FYI Will the Next Big Thing Be Really Small?

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