hussain (tsh476) – Homework 2 – Sutcliffe – (50985)
1
This
printout
should
have
20
questions.
Multiplechoice questions may continue on
the next column or page – find all choices
before answering.
This assignment covers the remaining ma
terial that will be in the first exam.
001
10.0 points
You are caught in a radar trap and hope to
show that the speed measured by the radar
gun is in error due to the uncertainty prin
ciple.
If you assume that the uncertainty in
your position is large, say about 10 m, and
that the car has a mass of 2150 kg, what is
the uncertainty in the velocity?
1.
4
×
10
38
m
/
s
2.
2
.
5
×
10

39
m
/
s
correct
3.
5
.
0
×
10

38
m
/
s
4.
1
×
10
33
m
5.
1
×
10

39
m
/
s
Explanation:
Δ
x
= 10 m
m
= 2150 kg
Δ
v
=
¯
h
2
m
Δ
x
=
1
.
055
×
10

34
J
·
s
2 (2150 kg) (10 m)
= 2
.
45349
×
10

39
m
/
s
002
10.0 points
In a onedimensional particle in a box, for
n
=
7, how many WHOLE wavelengths equals the
size of the box?
1.
3.5
correct
2.
6
3.
7
4.
14
Explanation:
For
n
= 7 the wavefunction would be
x
= 0
x
=
L
003
10.0 points
An electron is confined in a 1dimensional box
3 nm long. Calculate the energy required for
it to move from the
n
= 8 to the
n
= 9 energy
level.
1.
3
.
414
×
10

28
J
2.
1
.
138
×
10

19
J
correct
3.
6
.
694
×
10

21
J
4.
5
.
238
×
10

19
J
5.
2
.
133
×
10

14
J
6.
1
.
717
×
10

14
J
7.
2
.
133
×
10

19
J
Explanation:
n
1
= 8
n
2
= 9
h
= 6
.
626
×
10

34
J
·
s
L
= 13
×
10

9
m
m
= 9
.
109
×
10

31
kg
Δ
E
=
E
n
2

E
n
1
=
(
n
2
2

n
2
1
)
h
2
8
mL
2
=
(9
2

8
2
) (6
.
626
×
10

34
J
·
s)
2
8 (9
.
109
×
10

31
kg) (3
×
10

9
m)
2
= 1
.
13802
×
10

19
J
004
10.0 points
A quantum mechanical particle in a box in its
ground state is most likely to be found
1.
is equally likely to be found at all positions
except the very center of the box.
2.
is equally likely to be found at all positions
in the box.
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hussain (tsh476) – Homework 2 – Sutcliffe – (50985)
2
3.
at both edges of the box.
4.
in the middle of the box.
correct
5.
at the very edge of the box.
Explanation:
The ground state is Ψ
1
which has maximum
probability in the middle of the box.
005
10.0 points
For
n
= 7 and
ℓ
= 4, what is
m
ℓ
?
1.
18
2.
0, 1, 2, 3
3.
9
4.
0, 1, 2, 3, 4
5.

4,

3,

2,

1, 0, +1, +2, +3, +4
correct
Explanation:
006
10.0 points
Which of the following sets of quantum num
bers is allowed for an atomic orbital?
1.
n
= 3,
ℓ
= 1,
m
ℓ
= 0,
m
s
=

1
2
correct
2.
n
= 2,
ℓ
= 2,
m
ℓ
= 1,
m
s
=
1
2
3.
n
= 3,
ℓ
= 1,
m
ℓ
= 2,
m
s
=

1
2
4.
n
= 1,
ℓ
= 0,
m
ℓ
= 1,
m
s
=
1
2
5.
n
= 1,
ℓ
= 1,
m
ℓ
= 1,
m
s
= 1
Explanation:
007
10.0 points
In an atom, the maximum number of electrons
having the quantum numbers
n
= 5 and
ℓ
= 3
is
1.
25.
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 Spring '10
 McCord
 Atom, Electrons, Atomic orbital

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