mcdonald (pam78654) – HW 3A: Molecules – laude – (89560) 1
This print-out should have 16 questions.
Multiple-choice questions may continue on
the next column or page – find all choices
before answering.
001 10.0 points
Based only on the difference in electronega-
tivity (∆EN) identify the types of the labeled
bonds in the molecule below, from left to
right:
C
H
H
2
B
H
H1
C
S
b
b
b
b
3
O H
1. ionic, non-polar covalent, ionic
2. polar covalent, non-polar covalent, non-
polar covalent
3. polar covalent, non-polar covalent, polar
covalent correct
4. ionic, polar covalent, polar covalent
5. non-polar covalent, non-polar covalent,
polar covalent
Explanation:
The B-H bond will have a ∆EN of less than
2 but more than zero, and thus will be a
polar covalent bond. The C-C bond will have
a ∆EN of zero, and thus will be non-polar
covalent. The C=S bond will have a ∆EN of
less than 1 but more than zero, and thus will
be polar covalent.
002 10.0 points
Which of the following molecules is/are po-
lar?
I) C
F
H
C
F
H
II) C
F
H
C
H
F
III) C
F
F
C
H
H
1. III only
2. II only
3. II, III
4. I, II, III
5. I, III correct
6. I only
7. I, II
Explanation:
Molecule II is symmetrical and therefore its
individual dipole moments cancel, making it
non-polar. Molecules I and III are asymmet-
rical and therefore polar.
003 10.0 points
Which of the following is the correct Lewis
structure for ethene (C2H4)?
1. C
H
H
H
C H
2. C
H
H
C
H
H
