Chem1B, MC, Sp09, Lec Exam3                                                                     Name___________________________________
Read the questions carefully to understand it, before answering on the question paper. Transfer the answer on scantron after you are sure of your answer. To get partial points, show your calculation with set-up formula, understandable steps and proper units. Use  space on the question paper as scratch. 

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question.
1) Which substance is the reducing agent in the reaction below?
Pb  +  Pb  +  2S  →  2PbS  +  2O                                                                                          
1) _________

A) Pb	B) O	C) PbS 	D) S 	E) Pb 

2) The balanced half-reaction in which dichromate ion is reduced to chromium(III) ion is a __________ process.	2) _________

A) three-electron
B) six-electron
C) twelve-electron
D) two-electron
E) four-electron

3) The half-reaction occurring at the anode in the balanced reaction shown below is __________.

	3Mn (aq)  +  24 (aq)  +  5Fe (s)  →  3 (aq)  +  5 (aq)  +  12O (l) 
	3) _________

A) Fe (s)  →   (aq)  +  2
B)  (aq)  →   (aq)  +  
C) Mn  (aq)  +  8 (aq)  +  5  →   (aq)  +  4O (l)
D) 2Mn (aq)  +  12 (aq)  +  6  →  2 (aq)  +  3O (l)
E) Fe (s)  →   (aq)  +  3

4) In a voltaic cell, electrons flow from the __________ to the __________.	4) _________
A) salt bridge, cathode
B) salt bride, anode
C) cathode, anode
D) anode, cathode
E) anode, salt bridge

5) How many minutes will it take to plate out 2.19 g of chromium metal from a solution of  using a current of 35.2 amps in an electrolyte cell __________ ?	5) _________

A) 346	B) 17.3	C) 1.92	D) 5.77	E) 115

6) The standard cell potential () for the reaction below is +1.10 V. The cell potential for this reaction is __________ V when the concentration of  and  
	Zn (s)  +   (aq)  →  Cu (s)  +   (aq)
	6) _________

A) 0.95	B) 0.80	C) 1.25	D) 1.40	E) 1.10

	Table 20.2
	
7) The standard cell potential () for the voltaic cell based on the reaction below is __________ V.
	 (aq)  +  2 (aq)  →  2 (aq)  +   (aq)
	7) _________

A) -0.46	B) +1.39	C) +0.617	D) +0.46	E) +1.21

8) During the formation of a coordination compound, ligands act as __________.	8) _________
A) Arrhenius acids
B) Lewis bases
C) Arrhenius bases
D) Lewis acids
E) Br∅nsted bases

9) Formation of a complex species of  metal ion with ligands often __________.	9) _________
A) alters original physical properties of 
B) reduces availability of the free  ions in solution
C) "masks" original chemical properties of both the  ion and the ligands
D) may cause changes in the ease with which  is reduced or oxidized
E) all of the above

10) How many d electrons are in the cobalt ion of [Co(CN] __________ ?	10) ________
A) 7	B) 5	C) 4	D) 3	E) 6

11) Which one of the following substances has three unpaired d electrons?	11) ________
A) 
B) 
C) 
D) 
E) 

12) Which complex below has 2 unpaired electrons?	12) ________
A) low-spin octahedral 
B) tetrahedral 
C) square-planar 
D) tetrahedral 
E) octahedral 

13) Which one of the following complex ions will be paramagnetic?	13) ________
A)  (low spin)
B) 
C)  (low spin)
D) 
E)  (low spin)

14) Using the following abbreviated spectrochemical series, determine which complex ion is most likely to absorb light in the red region of the visible spectrum.

	small splitting    <  O  <  N  <    large splitting
	14) ________

A) 
B) 
C) 
D) 
E) not enough information given to determine

15) Which of the following cannot form both high- and low-spin octahedral complexes?	15) ________
A) 
B) 
C) 
D) 
E) All of the above can form both high- and low-spin complexes.

16) By what process does thorium-230 decay to radium-226    __________  ?	16) ________
A) beta emission
B) electron capture
C) alpha emission
D) positron emission
E) gamma emission

17)  In balancing the nuclear reaction U  →  E  +  He, the identity of element E is __________  .	17) ________

A) Th.	B) Np.	C) Pu.	D) U.	E) Pa.

18) This reaction is an example of __________. 

	Ca  →  K  +  __________	18) ________

A) beta decay
B) alpha decay
C) positron decay
D) gamma emission
E) electron capture

19) Nuclei above the belt of stability can lower their neutron-to-proton ratio by_____	19) ________
A) positron emission.
B) electron capture.
C) beta emission.
D) gamma emission.
E) Any of the above processes will lower the neutron-to-proton ratio.

20) What is the largest number of protons that can exist in a nucleus and still be stable   __________  ?	20) ________

A) 50	B) 206	C) 92	D) 84	E) 83

21) The beta decay of cesium-137 has a half-life of 30 years. How many years must pass to reduce a 25 mg sample of cesium 137 to 8.7 mg?	21) ________

A) 32	B) 3.2	C) 52	D) 46	E) 50

22) The decay of a radionuclide with a half-life of 4.3 ×  years has a rate constant (in ) equal to __________.	22) ________

A) 2.3 × .
B) 6.2 × .
C) 5.9 × .
D) 1.6 × .
E) 2.8 × .

23) The angles between  orbitals are __________.	23) ________
A) 180°	B) 90°	C) 120°	D) 109.5°	E) 45°

24) There are __________ σ and __________ π bonds in the CCC molecule.	24) ________
A) 6, 2	B) 4, 2	C) 2, 2	D) 2, 6	E) 6, 4

25) When two atoms ofH are fused to form one atom ofHe, the total energy evolved is  What is the total change in mass (in kg) for this reaction? 	25) ________

A) 4.26 × 
B) 3.45 × 
C) 1.15
D) 1.28 × 
E) 4.26 × 

26) What type of reaction is known as a thermonuclear reaction?	26) ________
A) transmutation
B) neutron emission
C) beta emission
D) fusion
E) fission

27) For a molecule with the formula A the molecular shape is __________.	27) ________
A) linear or T-shaped
B) linear or trigonal planar
C) linear or bent
D) trigonal planar
E) T-shaped

28) According to valence bond theory, which orbitals on bromine atoms overlap in the formation of the bond in ?	28) ________

A) 3s	B) 3p	C) 4s	D) 4p	E) 3d

29) In a typical multiple bond, the σ bond results from overlap of __________ orbitals and the π bond(s) result from overlap of __________ orbitals.	29) ________

A) hybrid or atomic, hybrid or atomic
B) atomic, hybrid
C) hybrid, hybrid or atomic
D) hybrid, hybrid
E) hybrid, atomic

TRUE/FALSE.  Choose 'A' if the statement is true and 'B' if the statement is false (4 pts each).
30) The electode where reduction occurs is called the anode.	30) ________

31) The standard reduction potential,, is proportional to the stoichiometric coefficient.	31) ________

32) If chloride is a ligand to a transition metal it will not be precipitated by silver nitrate. 	32) ________

33) Transition metal complexes  are colored because of the energy gap between the d orbitals.	33) ________

34) Transition  metal complexes, whose metal ions have the same number of unpaired electrons, are paramagnetic	34) ________

35) Gamma  radiation  only changes the atomic number but not the mass number of a nucleus. 	35) ________

36) Positron emission causes a decrease of one in the atomic number.	36) ________

37) Radioactive decay is a  first order kinetic process. 	37) ________

38) Hybridization is the process of mixing atomic orbitals as atoms approach each other to form a bond. 	38) ________

1) A
2) B
3) E
4) D
5) D
6) A
7) C
8) B
9) E
10) E
11) B
12) E
13) A
14) B
15) A
16) C
17) A
18) C
19) C
20) E
21) D
22) D
23) C
24) A
25) E
26) D
27) C
28) D
29) E
30) FALSE
31) FALSE
32) TRUE
33) TRUE
34) TRUE
35) FALSE
36) TRUE
37) TRUE
38) TRUE