Chemistry 105 Exam II November 30, 2007
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Multiple choice (3 pts. each) DARKEN THE CORRECT ANSWER ON THE ANSWER SHEET.
Remember there are also 3 problems given after the 22 multiple-choice questions. Budget your time
accordingly.
1. Which one of the following bonds would be the least polar?
a) N-F b) C-F c) Si-F d) O-F
2. Which one of the following ionic compounds would have the highest melting point?
a) K2O b) MgO
c) CaCl2d) KCl
e) NaBr
3. Based on formal charges, identify the most favorable resonance form of the cyanate ion.
a)
NCO
b)
NC O
c)
NC O
d) All are equivalent
4. The Lewis electron-dot structure of ClF3 gives the central Cl
a) 3 nonbonding pairs and 2 bonding pairs
b) 5 bonding pairs only
c) 2 nonbonding pairs and 4 bonding pairs
d) an octet
e) 2 nonbonding pairs and 3 bonding pairs
5. For the nitrite ion (NO2-),
a) both bonds are single bonds
b) both bonds are double bonds
c) both bonds are the same, each being stronger than a single bond but longer and weaker than a
double bond
d) one bond is a single bond and the other is a double bond
6. For resonance forms of a molecule or ion
a) one always corresponds to the actual observed structure
b) all always correspond to the actual observed structure
c) the same atoms need not be bonded to each other in all resonance forms
d) the actual observed structure is an average of the resonance forms
e) all always correspond to the actual observed structure and the same atoms need not be bonded to
each other in all resonance forms
Chemistry 105A –Exam 3: 2007 WHITE 1 / 4
