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 silicates B) chlorides and iodides C) nitrates and phosphates D) oxides and sulfides Answer: A Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 2) What minerals are important commercial sources of metals? A) aluminosilicates and silicates B) chlorides and iodides C) nitrates and phosphates D) oxides and sulfides Answer: D Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 3) What is a principal commercial ore for the element aluminum? A) bauxite B) chalcopyrite C) chromite D) hematite Answer: A Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 4) What is a principal commercial ore for the element iron? A) cassiterite B) cinnabar C) galena D) hematite Answer: D Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 1 Copyright © 2014 Pearson Education, Inc. 5) What is the most important copper containing ore? A) cassitrite B) chalcopyrite C) chromite D) cinnabar Answer: B Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 6) What metal is isolated from the ore galena? A) lead B) manganese C) tin D) zinc Answer: A Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 7) What metal is isolated from the ore sphalerite? A) copper B) manganese C) titanium D) zinc Answer: D Diff: 1 Topic: 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 ∙ xH2O B) manganese, MnO2 C) tin, SnO2 D) titanium, TiO2 Answer: D Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 2 Copyright © 2014 Pearson Education, Inc. 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: C Diff: 2 Topic: Section 21.1 Sources of the Metallic Elements 10) Which of the following metals occurs in nature principally as oxide ores? A) Ca B) Co C) Cr D) Cu Answer: C Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 11) Which substance is commonly found in nature in an uncombined form? A) aluminum B) iron C) platinum D) tin Answer: C Diff: 1 Topic: 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) Hf B) Hg C) K D) W Answer: B Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 3 Copyright © 2014 Pearson Education, Inc. 13) Which of the following elements is most likely to naturally occur as a carbonate? A) Ca B) Co C) Cr D) Cu Answer: A Diff: 1 Topic: Section 21.1 Sources of the Metallic Elements 14) 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 Answer: A Diff: 1 Topic: 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 reduction B) concentration of the ore C) reduction of the mineral to the free metal D) refining or purification of the metal Answer: A Diff: 1 Topic: Section 21.2 Metallurgy 16) 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 Answer: C Diff: 1 Topic: Section 21.2 Metallurgy 17) How is slag separated from molten ore in a blast furnace? A) chemical treatment B) density differences C) distillation D) magnetic differences Answer: B Diff: 1 Topic: Section 21.2 Metallurgy 4 Copyright © 2014 Pearson Education, Inc. 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 process B) bayer process C) contact process D) mond process Answer: B Diff: 1 Topic: 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 Hg B) Al, Mg, and Na C) Au and Pt D) Fe, Mn, and V Answer: A Diff: 1 Topic: Section 21.2 Metallurgy 20) When zinc sulfide undergoes roasting, the products are A) Zn and S. B) Zn and H2S. C) ZnO and S. D) ZnO and SO2. Answer: D Diff: 1 Topic: 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: D Diff: 1 Topic: Section 21.2 Metallurgy 5 Copyright © 2014 Pearson Education, Inc. 22) 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 Answer: A Diff: 1 Topic: Section 21.2 Metallurgy 23) Which of the following metals is not commonly obtained by electrolysis? A) Al B) Li C) Na D) Zn Answer: D Diff: 1 Topic: Section 21.2 Metallurgy 24) Which element is likely to be a principal impurity in zinc ore? A) cadmium B) copper C) gallium D) nickel Answer: A Diff: 1 Topic: Section 21.2 Metallurgy 25) 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 Answer: C Diff: 1 Topic: Section 21.2 Metallurgy 26) 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 Answer: D Diff: 1 Topic: Section 21.2 Metallurgy 6 Copyright © 2014 Pearson Education, Inc. 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 volume B) increase pressure C) increase temperature D) simultaneously increase the pressure and decrease volume Answer: C Diff: 1 Topic: 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 L B) 230 L C) 460 L D) 660 L Answer: A Diff: 2 Topic: 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: A Diff: 1 Topic: 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 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 Answer: C Diff: 2 Topic: 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 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 Answer: B Diff: 2 Topic: Section 21.3 Iron and Steel 7 Copyright © 2014 Pearson Education, Inc. 32) 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 Answer: D Diff: 1 Topic: Section 21.3 Iron and Steel 33) What is not a major component of slag? A) CaSiO3 B) Ca3(PO4)2 C) Fe2O3 D) MnSiO3 Answer: C Diff: 2 Topic: 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, acidic B) acidic, basic C) basic, acidic D) basic, basic Answer: C Diff: 1 Topic: 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 tons B) 20,000 metric tons C) 20,400 metric tons D) 30,000 metric tons Answer: C Diff: 2 Topic: Section 21.3 Iron and Steel 8 Copyright © 2014 Pearson Education, Inc. 36) 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 Answer: C Diff: 1 Topic: 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) Au B) Cs C) Re D) W Answer: D Diff: 3 Topic: Section 21.4 Bonding in Metals 38) Which of the following is the softest and most maleable? A) Cu B) V C) Ru D) Mn Answer: A Diff: 3 Topic: Section 21.4 Bonding in Metals 39) Which substance is the best conductor of electricity? A) diamond B) germanium C) gold D) phosphorus Answer: C Diff: 1 Topic: Section 21.4 Bonding in Metals Algo. Option: algorithmic 9 Copyright © 2014 Pearson Education, Inc. 40) 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. Answer: A Diff: 2 Topic: Section 21.4 Bonding in Metals 41) Which one of the following metals is expected to have the highest melting point? A) Cd B) Cr C) Hg D) Zn Answer: B Diff: 3 Topic: Section 21.4 Bonding in Metals Algo. Option: algorithmic 42) Electrical resistance of a metal ________ with increasing temperature. A) can decrease or increase B) decreases C) does not change D) increases Answer: D Diff: 1 Topic: 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 semiconductors B) only insulators C) only metals D) only semiconductors Answer: D Diff: 1 Topic: Section 21.5 Semiconductors 10 Copyright © 2014 Pearson Education, Inc. 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, metal B) metal, insulator C) metal, semiconductor D) semiconductor, metal Answer: C Diff: 1 Topic: Section 21.5 Semiconductors 45) Which of the following is a semiconductor? A) Al B) B C) Ga D) Pb Answer: B Diff: 1 Topic: Section 21.5 Semiconductors 46) Which one of the following is an electrical insulator? A) alumina B) germanium doped with antimony C) gold D) tellurium Answer: A Diff: 2 Topic: Section 21.5 Semiconductors Algo. Option: algorithmic 47) Which substance is a good semiconductor? A) diamond B) germanium C) gold D) phosphorus Answer: B Diff: 1 Topic: Section 21.5 Semiconductors 48) Which substance has a larger band gap than silicon? A) diamond B) copper C) germanium D) silver Answer: A Diff: 1 Topic: Section 21.5 Semiconductors 11 Copyright © 2014 Pearson Education, Inc. 49) Which element has the largest energy band gap? A) C (diamond) B) Si C) Ge D) Sn (white) Answer: A Diff: 1 Topic: Section 21.5 Semiconductors 50) Which element has the smallest energy band gap? A) C (diamond) B) Ge C) Pb D) Si Answer: C Diff: 1 Topic: Section 21.5 Semiconductors Algo. Option: algorithmic 51) How would one classify a germanium crystal doped with arsenic? A) conductor B) n-type semiconductor C) p-type semiconductor D) insulator Answer: B Diff: 1 Topic: Section 21.5 Semiconductors 52) How would one classify copper mixed with tin? A) conductor B) n-type semiconductor C) p-type semiconductor D) insulator Answer: A Diff: 2 Topic: Section 21.5 Semiconductors 53) How would one classify a silicon crystal doped with indium? A) conductor B) n-type semiconductor C) p-type semiconductor D) insulator Answer: C Diff: 1 Topic: Section 21.5 Semiconductors 12 Copyright © 2014 Pearson Education, Inc. 54) 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 Answer: B Diff: 1 Topic: Section 21.5 Semiconductors 55) 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 Answer: B Diff: 1 Topic: 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 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 Answer: B Diff: 4 Topic: 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: A Diff: 2 Topic: 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: A Diff: 2 Topic: Section 21.6 Semiconductor Applications 13 Copyright © 2014 Pearson Education, Inc. 59) 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 Answer: D Diff: 1 Topic: 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) diamond B) graphite C) fullerene D) potassium fulleride Answer: D Diff: 1 Topic: 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) 1 B) 3 C) 5 D) 16 Answer: B Diff: 1 Topic: 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) +1 B) +2 C) -2 - 2x/3 D) +2 + 2x/3 Answer: C Diff: 4 Topic: Section 21.7 Superconductors 14 Copyright © 2014 Pearson Education, Inc. 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) +2 B) +2.33 C) +3 D) +3.33 Answer: B Diff: 3 Topic: Section 21.7 Superconductors 64) Who discovered the phenomenon of superconductivity in 1911? A) J. G. Bednorz B) R. B. Fuller C) K. A. M ller D) H. K. Onnes Answer: D Diff: 1 Topic: Section 21.7 Superconductors 65) 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 Answer: D Diff: 1 Topic: 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: A Diff: 1 Topic: Section 21.7 Superconductors 67) 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 Answer: C Diff: 1 Topic: Section 21.7 Superconductors 68) What structural features appear necessary for superconductivity in the 1-2-3 YBa2Cu3O7 15 Copyright © 2014 Pearson Education, Inc. 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 Answer: B Diff: 2 Topic: 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) K3C60 D) YBa2Cu3O7 Answer: C Diff: 2 Topic: 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: C Diff: 1 Topic: Section 21.8 Ceramics 71) Which process is used in the fabrication of ceramics? A) electrolysis B) reduction C) roasting D) sintering Answer: D Diff: 1 Topic: Section 21.8 Ceramics 72) 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. Answer: B Diff: 1 Topic: Section 21.8 Ceramics 73) Why are ceramics so much more brittle than metals? 16 Copyright © 2014 Pearson Education, Inc. 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: D Diff: 2 Topic: Section 21.8 Ceramics 74) What substance has a rating of 10 on the Mohs hardness scale? A) alumina B) aluminum C) diamond D) talc Answer: C Diff: 1 Topic: Section 21.8 Ceramics 75) What is the name of the oxide ceramic BeO? A) beryllia B) beryllic C) beryllium ceramic D) beryllium oxide Answer: A Diff: 1 Topic: Section 21.8 Ceramics 76) What is not generally considered to be a ceramic? A) indium, In B) silica, SiO2 C) silicon nitride, Si3N4 D) zirconia, ZiO2 Answer: A Diff: 1 Topic: Section 21.8 Ceramics 77) What is the coordination number of Si in SiC that has a diamond-like structure? A) 1 B) 2 C) 4 D) 6 Answer: C Diff: 2 Topic: Section 21.8 Ceramics 17 Copyright © 2014 Pearson Education, Inc. 78) 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 Answer: C Diff: 1 Topic: 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 HOCH2CH3 C) (HO)3-Ti-OH + HO-Ti-(OH)3 → (HO)3-Ti-O-Ti(OH)3 + H2O D) 4 Ti(OH)4 + heat → 2 Ti2O3 + 8 H2O + O2 Answer: D Diff: 2 Topic: 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 HOCH2CH3 C) Si(OCH2CH3)4 + 4 HOCH3 → Si(OCH3)4 + 4 HOCH2CH3 D) Si(OCH3)4 + 4 H2O → Si(OH)4 + 4 HOCH3 Answer: B Diff: 2 Topic: Section 21.8 Ceramics 81) What is a cermet? A) boron nitride/epoxy B) ceramic-metal composite C) ceramic-polymer composite D) silicon carbide/graphite Answer: B Diff: 1 Topic: Section 21.9 Composites 18 Copyright © 2014 Pearson Education, Inc. 82) Silicon nitride/zirconia is a example of a A) ceramic-ceramic composite. B) ceramic-metal composite. C) ceramic-polymer composite. D) superconductor. Answer: A Diff: 2 Topic: Section 21.9 Composites 83) Relative to a bulk sample of gold, nanoparticles of gold have A) 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: B Diff: 1 Topic: 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 A B) element B C) element C D) element D Answer: A Diff: 1 Topic: Conceptual Problems 85) 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 Answer: C Diff: 1 Topic: Conceptual Problems 19 Copyright © 2014 Pearson Education, Inc. 86) Which of these elements is likely to be found in nature as a sulfide? A) element A B) element B C) element C D) element D Answer: D Diff: 1 Topic: Conceptual Problems 87) Which of these elements is likely to be found in nature as an oxide? A) element A B) element B C) element C D) element D Answer: B Diff: 1 Topic: Conceptual Problems 88) Which of these elements is likely to be extracted from its ore by roasting of a metal sulfide? A) element A B) element B C) element C D) element D Answer: D Diff: 1 Topic: Conceptual Problems 89) Which of these elements is likely to be extracted from its ore by chemical reduction of a metal oxide? A) element A B) element B C) element C D) element D Answer: B Diff: 1 Topic: Conceptual Problems 90) Which of these elements is likely to be extracted from its ore by electrolysis? A) element A B) element B C) element C D) element D Answer: A Diff: 1 Topic: Conceptual Problems 20 Copyright © 2014 Pearson Education, Inc. 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: D Diff: 1 Topic: 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: C Diff: 1 Topic: Conceptual Problems 21 Copyright © 2014 Pearson Education, Inc. 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: D Diff: 1 Topic: Conceptual Problems 94) Which of these materials is a metal? A) material (1) B) material (2) C) material (3) D) material (4) Answer: A Diff: 1 Topic: 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: C Diff: 1 Topic: Conceptual Problems 22 Copyright © 2014 Pearson Education, Inc. 96) Which of these materials has the highest electrical conductivity? A) material (1) B) material (2) C) material (3) D) material (4) Answer: A Diff: 1 Topic: 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: D Diff: 1 Topic: 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: C Diff: 1 Topic: 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: A Diff: 1 Topic: 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: D Diff: 1 Topic: Conceptual Problems 23 Copyright © 2014 Pearson Education, Inc. 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: C Diff: 3 Topic: Conceptual Problems 102) Which metal has the lowest melting point? A) metal (1) B) metal (2) C) metal (3) D) metal (4) Answer: D Diff: 3 Topic: Conceptual Problems 103) Which is the hardest metal? A) metal (1) B) metal (2) C) metal (3) D) metal (4) Answer: C Diff: 3 Topic: Conceptual Problems 24 Copyright © 2014 Pearson Education, Inc. 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: A Diff: 1 Topic: Conceptual Problems 105) Which picture corresponds to Ti? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: B Diff: 1 Topic: Conceptual Problems 106) Which picture corresponds to V? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: C Diff: 1 Topic: Conceptual Problems 25 Copyright © 2014 Pearson Education, Inc. 107) Which picture corresponds to Zn? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: D Diff: 1 Topic: 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: A Diff: 1 Topic: Conceptual Problems 109) Which picture corresponds to Mo? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: B Diff: 1 Topic: Conceptual Problems 26 Copyright © 2014 Pearson Education, Inc. 110) Which picture corresponds to Ag? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: C Diff: 1 Topic: Conceptual Problems 111) Which picture corresponds to Cd? A) picture (1) B) picture (2) C) picture (3) D) picture (4) Answer: D Diff: 1 Topic: 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: B Diff: 1 Topic: 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: A Diff: 1 Topic: Conceptual Problems 27 Copyright © 2014 Pearson Education, Inc. 114) In this picture the valence band is given by letter(s) A) a. B) b. C) c. D) a and b. Answer: C Diff: 1 Topic: 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: A Diff: 2 Topic: 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: B Diff: 2 Topic: Conceptual Problems 28 Copyright © 2014 Pearson Education, Inc. 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: C Diff: 2 Topic: 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: B Diff: 2 Topic: Conceptual Problems 29 Copyright © 2014 Pearson Education, Inc. 119) Which schematic best represents the electrical resistance versus temperature curve for a superconductor? A) A B) B C) C D) none of these Answer: A Diff: 1 Topic: Conceptual Problems 21.2 Algorithmic Questions 1) Which substance is the best conductor of electricity? A) arsenic B) boron C) silver D) tellurium Answer: C Diff: 1 Topic: Section 21.4 Bonding in Metals Algo. Option: algorithmic 2) Which one of the following metals is expected to have the highest melting point? A) La B) Nb C) Hg D) Pd Answer: B Diff: 3 Topic: Section 21.4 Bonding in Metals Algo. Option: algorithmic 30 Copyright © 2014 Pearson Education, Inc. 3) Which element has the smallest energy band gap? A) B B) I C) K D) S Answer: C Diff: 2 Topic: Section 21.5 Semiconductors Algo. Option: algorithmic 4) Which one of the following is an electrical insulator? A) phosphorus B) platinum C) potassium D) ruthenium Answer: A Diff: 2 Topic: Section 21.5 Semiconductors Algo. 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, + 2 Diff: 2 Topic: 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: 3 Topic: 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, CaO Diff: 2 Topic: Section 21.3 Iron and Steel 31 Copyright © 2014 Pearson Education, Inc. 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: Cr Diff: 3 Topic: 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: gray Diff: 1 Topic: 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: 16 Diff: 2 Topic: 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: 661 Diff: 4 Topic: Section 21.6 Semiconductor Applications 8) Nonoxide ceramics include silicon nitride, the formula of which is ________. Answer: Si3N4 Diff: 2 Topic: Section 21.8 Ceramics 9) Composite materials can be classified as ceramic-ceramic, ceramic-metal, or ceramicpolymer. Boron nitride/epoxy is classified as ________. Answer: ceramic-polymer. Diff: 2 Topic: 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, greater Diff: 2 Topic: FYI Will the Next Big Thing Be Really Small? 32 Copyright © 2014 Pearson Education, Inc.