1072-3rd-Chem Exam-1080619(A)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)__________ is the reducing agent in the reaction below.
Cr2O72- + 6S2O32- + 14H+ 2Cr3+ + 3S4O62- + 7H2O
A) H+ B) S2O32- C) S4O62- D) Cr3+ E) Cr2O72-
Answer: B
2)The half-reaction occurring at the cathode in the balanced reaction shown below is __________.
3MnO4- (aq) + 24H+ (aq) + 5Fe (s) 3Mn2+ (aq) + 5Fe3+ (aq) + 12H2O (l) A) 2MnO4- (aq) + 12H+ (aq) + 6e- 2Mn2+ (aq) + 3H2O (l)
B) Fe (s) Fe3+ (aq) + 3e-
C) MnO4- (aq) + 8H+ (aq) + 5e- Mn2+ (aq) + 4H2O (l) D) Fe (s) Fe2+ (aq) + 2e-
E) Fe2+ (aq) Fe3+ (aq) + e- Answer: C
3) The reduction half reaction occurring in the standard hydrogen electrode is __________.
A) 2H+ (aq, 1M) + 2e- H2 (g, 1 atm) B) H2 (g, 1 atm) 2H+ (aq, 1M) + 2e- C) 2H+ (aq) + 2OH- H2O (l)
D) O2 (g) + 4H+ (aq) + 4e- 2H2O (l) E) 2H+ (aq, 1M) + Cl2 (aq) 2HCl (aq) Answer: A
4) Corrosion of iron is retarded by __________.
A) high pH conditions B) low pH conditions C) the presence of salts
D) both the presence of salts and high pH conditions E) both the presence of salts and low pH conditions Answer: A
5) The standard cell potential (E°) of a voltaic cell constructed using the cell reaction below is 0.76 V:
Zn (s) + 2H+ (aq) Zn2+ (aq) + H2 (g)
With PH2 = 1.0 atm and [Zn2+] = 1.0 M, the cell potential is 0.66 V. The concentration of H+ in the cathode compartment is __________ M.
A) 1.0 × 10-12 B) 1.4 × 10-1 C) 4.9 × 101 D) 4.2 × 10-4 E) 2.0 × 10-2 Answer: E
7) Which transformation could take place at the anode of an electrochemical cell?
A)HAsO2 to As B) Cr2O72- Cr2+
C) F2 toF- D)O2 to H2O
E) None of the above could take place at the anode.
Answer: E Table 20.1
Half Reaction E°(V)
F2 (g) + 2e- 2F- (aq) +2.87
Cl2 (g) + 2e- 2Cl- (aq) +1.359 Br2 (l) + 2e- 2Br- (aq) +1.065 O2 (g) + 4H+ (aq) + 4e- 2H2O (l) +1.23
Ag+ + e- Ag (s) +0.799
Fe3+ (aq) + e- Fe2+ (aq) +0.771
I2 (s) + 2e- 2I- (aq) +0.536
Cu2+ + 2e- Cu (s) +0.34
2H+ + 2e- H2 (g) 0
Pb2+ + 2e- Pb (s) -0.126
Ni2+ + 2e- Ni (s) -0.28
Li+ + e- Li (s) -3.05
8) Which of the halogens in Table 20.1 is the strongest oxidizing agent?
A)Br2 B)Cl2 C)I2 D)F2
E) All of the halogens have equal strength as oxidizing agents.
Answer: D
9) Consider an electrochemical cell based on the reaction:
2H+ (aq) + Sn (s) Sn2+ (aq) + H2 (g)
Which of the following actions would not change the measured cell potential?
A) increasing the pressure of hydrogen gas in the cathode compartment B) increasing the tin (II) ion concentration in the anode compartment C) lowering the pH in the cathode compartment
D) addition of more tin metal to the anode compartment E) Any of the above will change the measured cell potential.
Answer: D
10) Cathodic protection of a metal pipe against corrosion usually entails
A) coating the pipe with another metal whose standard reduction potential is less negative than that of the pipe.
B) attaching an active metal to make the pipe the cathode in an electrochemical cell.
C) coating the pipe with a fluoropolymer to act as a source of fluoride ion (since the latter is so hard to oxidize).
D) attaching a dry cell to reduce any metal ions which might be formed.
E) attaching an active metal to make the pipe the anode in an electrochemical cell.
Answer: B
11) Carbon-11 is used in medical imaging. The half-life of this radioisotope is 20.4 min. What percentage of a sample remains after 60.0 min?
A) 13.0 B) 34.0 C) 5.28 D) 71.2 E) 2.94
Answer: A
12) Carbon-11 decays by positron emission:
116 C 11 5 B + 01e
The decay occurs with a release of 2.87 × 1011 J per mole of carbon-11. When 4.00 g of carbon-11 undergoes this radioactive decay, __________ g of mass is converted to energy.
A) 3.48 × 105 B) 1.28 × 10-2 C) 1.16 × 10-3 D) 1.16 × 10-6 E) 8.62 × 102 Answer: C
13) In balancing the nuclear reaction 23892U 234
90E + 42He, the identity of element E is __________.
A) Np B) U C) Th D) Pa E) Pu
Answer: C
14) The missing product from this reaction is __________.
10
5 B + _____ 13 7 N + 1
0n
A) 42He B) 01e C) 10n D) 0-1e E) 00
Answer: A
15) This reaction is an example of __________.
4120Ca 41
19K + _____
A) beta decay B) gamma emission C) electron capture D) positron decay
E) alpha decay Answer: D
17) What order process is radioactive decay?
A) zeroth B) first C) second D) third E) fourth
Answer: B
18) What drives the turbine in a nuclear power plant?
A) the primary coolant B) the moderator C)UF6 gas D) steam
E) the control rods Answer: D
19) In the nuclear transmutation represented by 168O(p, ) 13
7N, the emitted particle is __________.
A) a positron.
B) a neutron.
C) an alpha particle.
D) a beta particle.
E) a proton.
Answer: C
20) Atoms containing radioactive nuclei are called __________.
A) radionuclides B) radioisophores C) nuclides D) radioisotopes
E) nucleons Answer: D
21) What two oxidation states are more frequently observed in the first transition series than in the third?
A) +2 and +3 B) +3 and +5 C) +5 and +6 D) +2 and +7 E) +3 and +7
Answer: A
22) The lanthanide contraction is responsible for the fact that A) Zr and Zn have similar oxidation states.
B) Zr and Y have about the same radius.
C) Zr and Hf have the same oxidation states.
D) Zr and Nb have similar oxidation states.
E) Zr and Hf have about the same radius.
Answer: E
23) Which one of the following species is paramagnetic?
A) Cr3+ B) Ca C) Cu+ D) Ag+ E) Zn
Answer: A
24) The coordination number of cobalt in CoCl3 · 6NH3 is __________.
A) 2 B) 8 C) 4 D) 6 E) 3
Answer: D
25) Changes in the coordination sphere of a complex compound may lead to changes in __________.
A) physical properties B) chemical properties C) stability
D) color
E) all of the above Answer: E
26)Does either or both cis- or trans-[Mn(en)2Br2] have optical isomers?
A) cis only B) trans only C) both cis and trans D) neither cis nor trans
E)[Mn(en)2Br2] does not exhibit cis-trans isomerism.
Answer: A
27) Which of the following will display optical isomerism?
A) octahedral [Co(NH3)6]3+
B) square-planar [Pt(H2NC2H4NH2)2] 2+
C) octahedral [Co(NH3)5Cl]2+
D) square-planar [Rh(CO)2Cl2] - E) octahedral [Co(H2NC2H4NH2)3]3+
Answer: E
28) A complex that absorbs light at 700 nm will appear __________.
A) violet B) yellow C) green D) orange E) red
Answer: C
29) Which one of the following complex ions will be paramagnetic?
A) [Fe(H2O)6]3+ (low spin) B) [Fe(H2O)6]2+ (low spin) C) [Co(H2O)6]3+ (low spin) D) [Zn(NH3)4]2+
E) [Zn(H2O)4]2+
Answer: A
30) Which one of the following ions cannot form both a high spin and a low spin octahedral complex ion?
A) Cr3+ B) Cr2+ C) Co2+ D) Fe3+ E) Mn3+
Answer: A
31) If each of the following represents an alkane, and a carbon atom is located at each vertex with the proper number of hydrogen atoms also bonded to it, which one is the most reactive?
A)
B)
C)
D)
E) They are all equally reactive since they are all alkanes.
Answer: A
32) Benzene behaves differently from a hydrocarbon which simply contains three C C bonds in that the latter would be expected to react much more readily with __________.
A)Br2 B) HCl C)Cl2 D)H2
E) all of the above Answer: E
33) The oxidation of ethanol produces __________.
A) acetic acid B) oxalic acid C) lactic acid D) formic acid E) citric acid Answer: A
34) The melting and boiling points of hydrocarbons are determined by __________.
A) ionic bonding
B) dipole-dipole attraction C) hydrogen bonding D) ion-dipole attraction
E) London forces Answer: E
35) __________ acts as a kind of energy bank in the body, and is found concentrated in muscles and liver.
A) Cellulose B) Lactose C) Sucrose D) Starch E) Glycogen
Answer: E
36) Which structure below represents an amine?
A)
B)
C)
D)
E)
Answer: D
37) How many chiral carbon atoms does the neopentane (2, 2 - dimethylpropane) have?
A) 1 B) 2 C) 3 D) 4 E) 0
Answer: E
38) Hybridization of the carbon atom indicated by (*) in CH3-*CH2-CH3, *CH2 CH2, and CH3-*C CH is __________, __________, and __________, respectively.
A) sp3, sp2, sp B) sp2, sp3, sp C) sp, sp3, sp2 D) sp3, sp, sp2 E) sp, sp2, sp3 Answer: A
39) The addition of HBr to 2-butene produces __________.
A) 2,3-dibromobutane B) 1-bromobutane C) no reaction D) 2-bromobutane
E) 1,2-dibromobutane Answer: D
40) How many chiral atoms does the open-chain form of glucose have?
A) 4 B) 1 C) 5 D) 2 E) 3
Answer: A
