AAMC MCAT test 9

MCAT
Practice Test 9


Association of American Medical Colleges

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Physical Sciences
Time: 100 minutes
Questions: 1-77
Most questions in the Physical Sciences test are organized into groups, each containing a descriptive passage.
After studying the passage, select the one best answer to each question in the group. Some questions are not
based on a descriptive passage and are also independent of each other. If you are not certain of an answer,
eliminate the alternatives that you know to be incorrect and then select an answer from the remaining
alternatives. Indicate your selected answer by marking the corresponding answer on your answer sheet. A
periodic table is provided for your use. You may consult it whenever you wish.

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Periodic Table of the Elements

1

H

2

He
4.0
10

1.0
3

4

Li

Be

B

C

N

O

F

Ne

6.9

9.0

10.8

12.0

14.0

16.0

19.0

20.2

5

6

7

8

9

11

12

13

14

15

16

17

18

Na

Mg

Al

Si

P

S

Cl

Ar

23.0

24.3

27.0

28.1

31.0

32.1

35.5

39.9

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

39.1
37

40.1
38

45.0
39

47.9
40

50.9
41

52.0
42

54.9
43

55.8
44

58.9
45

58.7
46

63.5
47

65.4
48

69.7
49

72.6
50

74.9
51

79.0
52

79.9
53

83.8
54

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

85.5
55

87.6
56

88.9
57

91.2
72

92.9
73

95.9
74

(98)
75

101.1
76

102.9
77

106.4
78

107.9
79

112.4
80

114.8
81

118.7
82

121.8
83

127.6
84

126.9
85

131.3
86

Cs

Ba

La*

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

132.9
87

137.3
88

138.9
89

178.5
104

180.9
105

183.9
106

186.2
107

190.2
108

192.2
109

195.1

197.0

200.6

204.4

207.2

209.0

(209)

(210)

(222)

Fr

Ra

Ac†

Unq†

Unp

Unh

Uns Uno Une

(223)

(226)

(227)

(261)

(262)

58

(263)
59

(262)
60

(265)
61

(267)
62

63

64

65

66

67

68

69

70

71

Ce

Pr

Nd

Pm

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

140.1
90

140.9
91

144.2
92

(145)
93

150.4
94

152.0
95

157.3
96

158.9
97

162.5
98

164.9
99

167.3
100

168.9
101

173.0
102

175.0
103

*

† Th
232.0

Pa

U

Np

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

(231)

238.0

(237)

(244)

(243)

(247)

(247)

(251)

(252)

(257)

(258)

(259)

(260)


Passage I
A group of students investigated the properties of
solutions containing Na+, Mg2+, Ca2+, Sr2+, and Ba2+.
Flame Test
The students prepared 0.1 M aqueous solutions of
each metal nitrate. They dipped a Pt loop into each
solution and heated a drop of each solution over a
flame. They recorded the color of the flame (Table 1).
They repeated the flame test with Unknown A, a
solution that contained two of the metal nitrates.
Solubility Test
The students prepared 1.0 M aqueous solutions of
four reagents.

1. A solution contains 0.1 M Mg2+(aq), 0.1 M
Ca2+(aq), and 0.1 M Sr2+(aq). All three ions can
be precipitated if which two reagents are added to
the solution?
A) Reagents 1 and 2
B) Reagents 1 and 3

C) Reagents 2 and 3
D) Reagents 2 and 4
2. A test tube contains 2 mL of 0.1 M Ca2+(aq). A
precipitate will most likely form if which of the
following reagents is added to the tube?
A) 1.0 M HCl(aq)

Reagent 1 = NH3(aq)
Reagent 2 = (NH4)2SO4(aq)
Reagent 3 = (NH4)2C2O4(aq)
Reagent 4 = (NH4)2CO3(aq)
They combined 1.0 mL of each metal nitrate solution
with 1.0 mL of each reagent, and the solution either
remained clear or a white precipitate formed (Table
1).
Table 1 Results of Flame Test and Solubility Test of
Metal Nitrate Solutions

Metal ion
Na+(aq)
2+

Mg (aq)
2+

Color
of
flame
yellow
no

color

Ca (aq)

red

Sr2+(aq)

red

2+

Ba (aq)

green

Unknown
A

red

Appearance of solution after reagent was
added
Reagent Reagent Reagent Reagent
1
2
3
4
clear
clear

clear
clear
white
clear
clear
clear
ppt
white
white
clear
clear
ppt
ppt
white
white
white
clear
ppt
ppt
ppt
white
white
white
clear
ppt
ppt
ppt
white
white
white

white
ppt
ppt
ppt
ppt

Note: ppt = precipitate

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B) 1.0 M NaOH(aq)
C) 1.0 M H2SO4(aq)
D) 1.0 M Na2CO3(aq)
3. The students added Reagent 2 to a test tube
containing 0.1 M Ca2+(aq) and 0.1 M Sr2+(aq).
Which of the following procedures will best
enable the students to recover a fairly pure sample
of SrSO4(s) from this mixture?
A) Allowing the water to evaporate and collecting the
solid that remains in the tube
B) Pouring the mixture through a filter, collecting the
insoluble substance, and allowing the water to
evaporate from the insoluble substance
C) Pouring the mixture through a filter, collecting the
filtrate containing the soluble substance, then
allowing the water to evaporate from the filtrate
D) Adding Reagent 3, pouring the mixture through
a filter, collecting the filtrate containing the
soluble substance, and allowing the water to
evaporate from the filtrate

4. The information in Table 1 suggests that which of
the following substances has the smallest Ksp?
A) MgSO4
B) MgC2O4
C) CaSO4
D) CaC2O4

5. A solution contains either Ca2+(aq) or Sr2+(aq).
Which of the following actions will best enable the
students to identify the ion in the solution?
A) Performing a flame test
B) Adding Reagent 1
C) Adding Reagent 2
D) Adding Reagent 3

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Passage II
Students constructed the electrical circuit shown
below to study capacitors. A battery with a voltage of
10 V is connected through a switch to a capacitor and
a 500-Ω resistor. The capacitor is constructed from
two flat metal plates, each with a surface area of 5.0 ×
10–5 m2. The plates are separated by 1.0 × 10–3 m, and
the space between the plates is a vacuum. The
connecting wires have no resistance. After the switch
is closed and the capacitor is fully charged, a particle

with a charge of 8.0 × 10–19 C and a speed of 1.0 m/s
is injected midway between the capacitor plates.

6. Which of the following graphs best illustrates how
charge accumulates on the plates of the capacitor
after the switch is closed?
A)

B)

C)

Figure 1 Circuit

D)

7. If the speed of the charged particle described in the
passage is increased by a factor of 2, the electrical
force on the particle will:
A) decrease by a factor of 2.
B) remain the same.
C) increase by a factor of 2.
D) increase by a factor of 4.
8. Making which of the following changes to a circuit
element will increase the capacitance of the
capacitor described in the passage?
A) Replacing the 500-Ω resistor with a 250-Ω resistor
B) Replacing the 10-V battery with a 20-V battery
C) Increasing the separation of the capacitor plates
D) Increasing the area of the capacitor plates

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9. A charged particle with a mass of m and a charge
of q is injected midway between the plates of a
capacitor that has a uniform electric field of E.
What is the acceleration of this particle due to the
electric field?

11. Which of the following best describes the motion
of a negatively charged particle after it has been
injected between the plates of a charged, parallelplate capacitor? (Note: Assume that the area
between the plates is a vacuum.)

A) Eq/m

A) It moves with constant speed toward the positive
plate.

B) Em/q
C) mq/E
D) Emq
10. Another capacitor, identical to the original, is
added in series to the circuit described in the
passage. Compared to the original circuit, the
equivalent capacitance of the new circuit is:
A) 1/2 as great.
B) the same.
C) 2 times as great.
D) 4 times as great.

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B) It moves with constant speed toward the negative
plate.
C) It accelerates toward the positive plate.
D) It accelerates toward the negative plate.


Passage III
Gasoline is a mixture of nonpolar hydrocarbons
that reacts with oxygen in an automobile engine to
produce energy, carbon dioxide, and water vapor. If
the gasoline burns too rapidly, a metal piston can be
slammed against a metallic part, resulting in a
“knocking” sound and a reduction in engine
efficiency. The octane rating of a gasoline is a
measure of its antiknock qualities. The higher the
octane rating of a hydrocarbon mixture, the slower it
burns and the smoother the piston operates.
The octane rating scale derives its name from
isooctane (C8H18), a hydrocarbon with good
antiknock qualities. A 90:10 mixture of isooctane and
heptane (C7H16) has an octane rating of 90.
Oxygenates are oxygen-containing compounds that
can be added to a gasoline to increase the octane
rating. Two oxygenates currently in use are MTBE
and ETOH. Data for these oxygenates and two other
potential additives are shown in Table 1. A
disadvantage of MTBE is that it has a strong and

offensive odor that humans can smell even at
concentrations below 0.26 ppm in air.

13. The formation of one mole of which oxygenate
shown in Table 1 releases the most energy?
A) ETOH
B) MTBE
C) ETBE
D) TAME
14. What are the coefficients for oxygen and carbon
dioxide, respectively, if the equation shown
below is balanced?
1CH3OCH3(ℓ ) + ? O2(g) → __ H2O(g) + ? CO2(g)

A) 2 and 1
B) 2 and 2
C) 3 and 1
D) 3 and 2
15. Which of the following nonoxygenated analogs
of MTBE is most likely to mimic MTBE in its
antiknock properties?
A) C4H9Si(CH3)3

Table 1 Data for Gasoline Additives

B) C4H9N(CH3)2

Additive
MTBE
ETOH

ETBE
TAME

Formula
C4H9OCH3
C2H5OH
C4H9OC2H5
C5H11OCH3

Octane
rating
110
115
112
111

Vapor
pressure
(torr, 25°C)

Heat of
formation
(kJ/mole)

25
58
20
15

–580

–278
–675
–680

C) C4H9SCH3
D) C4H9P(CH3)2
16. The entropy change for the combustion reaction
of gasoline is always greater than zero because
the:

12. What type of intermolecular interaction can
ETOH undergo with water that MTBE can NOT?

A) number of gaseous molecules in the products
always exceeds the number of gaseous molecules
in the reactants.

A) van der Waals

B) enthalpy change is always positive.

B) Dipole–dipole

C) temperature of the combustion is always more
than 100°C.

C) Hydrogen bonding
D) Covalent bonding

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D) free energy change is always positive.


17. Which compound shown in Table 1 evaporates
fastest at 30°C?
A) MTBE

18. If one mole of each additive shown in Table 1
undergoes complete combustion, which
compound requires the least amount of oxygen?

B) ETOH

A) MTBE

C) ETBE

B) ETOH

D) TAME

C) ETBE
D) TAME

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Passage IV
The detection of low-frequency pressure waves in

stars, infrasonic waves, offers astronomers an insight
into stellar structure. Such waves are observed in the
Sun (with frequencies around 3.3 × 10–3 s–1) and are
now being detected in large, bright nearby stars. In
one method of detecting them, one looks for Doppler
shifts in light emissions; the Doppler-shifted light
shows periodicities typical of the pressure waves
producing the motion.
The pressure waves can be likened to standing
waves in a pipe open at both ends, and an inner layer
of the star can be taken as a large number of
neighboring, outwardly directed columns of gas—
much like a collection of pipes. The relationships
derived for ordinary pipes are then useful. In a gas of
density ρ and bulk modulus B, the harmonic
frequencies fn for a pipe of length L are given by

19. A collection of an unspecified number of
neighboring gas columns, or pipes, can
reasonably be used to represent the layer of a star
in which pressure waves occur because the:
A) harmonic frequencies of a pipe are independent of
its diameter.
B) harmonic frequencies of a pipe are independent of
its length.
C) speed of sound in gas confined to a pipe is
independent of gas density.
D) speed of sound propagating upward against
gravity decreases with height.
20. As an aid in identifying the various resonant

pressure-wave frequencies in the Sun and stars,
one can use the fact that:
A) the Doppler-shifted light is easily recognized,
being polarized in a way that is characteristic of
hydrogen.

where n = 1, 2, 3, . . . , the speed of sound vs is

and the constant B is defined in terms of pressure
and volume changes

B) the Doppler-shifted light stands out, being
steadier in intensity than the unshifted light
emissions that accompany it.
C) resonant frequencies are always separated by
increments that are equal to a basic number
multiplied by an integer.
D) resonant frequencies in hydrogen gas depend
strongly on its degree of gas ionization, which, in
turn, depends on temperature.

Observations are difficult because of the small
velocity changes in the gas, about 1 m/s, associated
with the pressure waves. One needs abundant data
(large, bright stars) to separate the Doppler shifts due
to pressure waves from those of thermal origin. A
new, different observational technique may help.
Stellar atmospheres are mostly hydrogen atoms, and
many are in an excited state—the electron in energy
level 2. The fraction in level 2 is extremely

temperature sensitive, increasing as T 6. So slight
pressure changes vary the intensity of light at the
wavelengths associated with transitions into or out
of level 2. These, in fact, are mostly from level 2 to
level 3, which is associated with light of wavelength
0.6563 × 10–6 m.
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21. In the newer observational technique discussed,
one makes use of the fact that:
A) the hydrogen gas in the observed stellar
atmospheres is completely ionized.
B) stellar atmospheres are open to space, so that
pressure and temperature are independent of
volume.
C) pressure waves in stars propagate upward very
slowly, generally at about 1 m/s.
D) light is absorbed or emitted whenever electrons
move from one energy level to another.


22. The surface temperature of one of the
observed
stars is 6000 K. The fraction of its surface
hydrogen atoms having electrons in energy
level
2 then increases by how much for each 1 K
temperature rise?
A) (6001/5999)6
6

B) (6001/6000)

1.002, so 2 parts in 1000
1.001, so 1 part in 1000

6

1.02, so 2 parts in 100

6

1.01, so 1 part in 100

C) (274/273)

D) (461/460)

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These questions are not based on a descriptive
passage and are independent of each other.
23. H2O is liquid at room temperature, whereas H2S,
H2Se, and H2Te are all gases. Which of the
following best explains why H2O is liquid at
room temperature?

25. If the second floor and the top floor of a building
are separated by a distance of 100 m, what is the

approximate difference between the air pressures
of the two levels? (Note: Air density = 1.2
kg/m3 and gravitational acceleration = 10 m/s2.
Neglect the compressibility of air.)
A) 600 N/m2

A) Hydrogen bonds form between H2O molecules.

B) 800 N/m2

B) Oxygen lacks d orbitals.

C) 1000 N/m2

C) H2O has a lower molecular weight.

D) 1200 N/m2

D) H2O is more volatile.
26. What is the pH of a .001 M NaOH solution?
24.

A) .001
B) 3
C) 7
D) 11

How do the pressures Pw and Pm compare,
measured at the bottom of two identical
containers filled to the levels shown in the figure

with water and mercury? (Note: Density of
water = 1 g/cm3; density of mercury = 14 g/cm3.)
A) Pm = 2Pw
B) Pm = 7Pw
C) Pm = 14Pw
D) Pm = 28Pw

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Passage V
The interaction between metals and hydrocarbons
is important in both biological and industrial
catalysis. Researchers are probing the fundamental
chemistry of these interactions by measuring the gasphase reactivity of transition-metal atoms with
hydrocarbons. In a typical reaction, metal atoms are
introduced into a helium buffer gas at the head of a
73-cm fast-flow tube. Table 1 shows the initial helium
and metal gas-flow conditions.
Table 1 Initial Flow Conditions
Pressure
(torr)
0.5
0.8
1.1

Mole fraction
He
0.93
0.96

0.98

Metal velocity
(cm s–1)
8160
9070
9420

and d orbitals of similar energy form sd hybrid
orbitals, enhancing the reaction.
Table 2 Rate Constants, k (10–12 cm3 s–1), at Three
Pressures
Metal
Ti
Zr
Hf
V
Nb
Ta

Pressure (torr)
0.5 0.8 1.1
— NR —
— 59 28
29 28 28
— NR —
— 314 —
9.6 8.4 —

Metal

Ni
Pd
Pt
Cu
Ag
Au

Pressure (torr)
0.5 0.8 1.1
— 0.5 —
—
15
—
387 376 351
— NR —
— NR —
— NR —

27. Why did the researchers choose helium as a
buffer gas?
A) It is chemically inert and has no effect on the rate.
B) It catalyzes the reaction, increasing the rate.

A large excess of a hydrocarbon gas such as
ethene is then injected into the metal gas stream, and
the rate of the reaction is measured by monitoring the
concentration of unreacted metal versus reaction time
(distance/velocity).

C) It collides with metal atoms, decreasing their

kinetic energy and the rate.

Equation 1 shows a proposed one-step reaction
mechanism for the reaction of a metal (M) with a
hydrocarbon (HC).

28. If the reaction tube described in the passage is 2 cm
in diameter and an initial helium–metal mixture
displays ideal gas behavior, which of the following
expressions gives the number of moles of He in the
tube at 1.1 torr and 298 K? (Note: R = 0.082 L atm
K–1 mol–1.)

M(g) + HC(g) → product
Equation 1
If the HC(g) is in a large excess, its concentration
is considered to be constant, and the rate expression
shown in Equation 2 is obtained, in which [M] is the
concentration of metal at time t, and k and k1 are rate
constants.
ln [M/Mo] = –k1[HC]t = –kt
Equation 2
Several rate constants reported for metal reactions
with ethene at 298 K are shown in Table 2 (NR = no
reaction). The researchers suggest that two effects
involving metal orbitals influence the reaction rate. A
full valence s subshell hinders reaction, and valence s

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D) Its atoms are approximately the same size as the
metal atoms, and they have no effect on the rate.

A) [(1.1)(π)(1)2(0.98)]/[(1000)(760)(0.082)(298)]
B) [(1.1)(π)(1)(73)2(0.98)]/[(1000)(760)(0.082)(298)]
C) [(1.1)(π)(2)2(73)(0.98)(4.0)]/[(1000)(760)(0.082)(298)]
D) [(1.1)(π)(1)2(73)(0.98)]/[(1000)(760)(0.082)(298)]


29. What does a nonlinear plot of ln [M] versus t
indicate about the concentration of the
hydrocarbon (HC) and the reaction mechanism?

31. The metals shown in Table 2 belong to which
block of elements in the periodic table?

A) The HC is not in excess, and the mechanism is
(fast)
M + heat → M*
(slow)
M* + HC → product

B) p

B) The HC is in excess, and the mechanism is
(fast)
M + heat → M*
(slow)
M* + HC → product

D) f

C) The HC is not in excess, and the mechanism is
(slow)
M + heat → M*
(fast)
M* + HC → product
D) The HC is in excess, and the mechanism is
(slow)
M + heat → M*
(fast)
M* + HC → product
30. According to Table 2 and information in the
passage, the reactivity of platinum (5d 96s1)
relative to gold (5d 106s1) is attributable to the
metal–HC interaction, which involves:
A) only valence s electrons.
B) sd hybrid orbitals.
C) sp hybrid orbitals.
C) only valence d electrons.

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A) s
C) d

32. Ta reacts slower than Nb (Table 2) because:
A) the valence s orbitals of Ta have a much higher
energy than do its valence d orbitals.
B) the valence s orbitals of Ta have a much lower

energy than do its valence d orbitals.
C) the valence s orbitals of Nb have a much higher
energy than do its valence d orbitals.
D) Ta forms especially stable sd hybrid orbitals.
33. Which of the following expressions gives the
percent mass of hafnium (Hf) in an initial
mixture of He–Hf at 0.5 torr?
A) [(0.93)(4.0)(100)]/[(0.07)(178.5) + (0.93)(4.0)]
B) [(90.07)(72)(100)]/[(0.07)(972) + (0.93)(2)]
C) [(0.07)(178.5)(100)]/[(0.07)(178.5)+(0.93)(4.0)]
D) [(0.07)(200.6)(100)]/[(0.07)(200.6) + (0.93)(4.0)]


Passage VI
The effectiveness of a tire is determined by its
coefficients of kinetic and static friction under
different road conditions. The coefficient of static
friction is defined by µS = F(max static)/F(normal),
and for kinetic friction µK = F(kinetic)/F(normal).
The forces refer to the maximum static frictional
force required to start a tire moving, the normal force
exerted by the road supporting the tire, and the kinetic
frictional force on a rolling tire. These coefficients are
properties of the road and tire surfaces. The
coefficients are measured in two experiments.
Experiment 1
A tire is mounted on a wheel whose axle is locked
so that the tire cannot roll on the road. The axle
carries weights to a total mass of 500 kg (axle plus
wheel and tire) to simulate the load the tire would

experience during normal use. A light rope pulls
horizontally on the axle. During the experiment, the
force on the rope is steadily increased until the tire
begins to skid along the road without rotating. Once
the tire starts to skid, the dragging force is reduced to
the minimum needed to maintain a steady speed.
Table 1 shows the pulling force versus time data for a
measurement made on a dry road.
Table 1 Data from Experiment 1
Time (s)
0
1
2
3
4
5
6
7
8
9

Force (N)
0
1500
3000
4500
6000
7500
6000
6000

6000
6000

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Experiment 2
The road conditions are the same as for
Experiment 1 but the tire is now allowed to roll. At
some instant the axle of the rolling tire is locked as if
brakes were applied. The tire skids 24.0 m before
coming to rest. During the skid the speed decreases
steadily for 2.00 s before the tire comes to rest.
(Note: Approximate the acceleration due to
gravity as 10 m/s2.)
34. In Experiment 1, the acceleration of the hub of
the tire during the first 4 s is:
A) a nonzero constant in the direction of the frictional
force.
B) a nonzero constant in the direction of the pulling
force.
C) increasing steadily as the pulling force increases.
D) constant and zero.
35. What is the coefficient of static friction in
Experiment 1?
A) 1.5
B) 1500
C) 6000 N
D) 7500 N
36. What is the coefficient of kinetic friction in
Experiment 1?

A) 1500 N
B) 6000 N
C) 1.2
D) 1.5


37. The initial translational kinetic energy of the
wheel system in Experiment 2 (just before
applying the brakes):
A) is less than the magnitude of work required to
stop the tire.

38. If a tire with a radius of 0.5 m is rolling with an
angular frequency of 30 rad/s, how far will the
axle travel in 2 s?
A) 5 m

B) is equal to the magnitude of work required to stop
the tire.

B) 10 m

C) is greater than the magnitude of work required to
stop the tire.

D) 30 m

D) cannot be determined from the information given.

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C) 20 m


Passage VII
The compounds nitric acid (HNO3), nitrous acid
(HNO2), acetic acid (CH3COOH), hypochlorous acid
(HClO), and ammonium nitrate (NH4NO3), are all
water soluble and produce acidic solutions. The Ka
values for these compounds are given in Table 1.
Table 1 Ka Values
Compound
HNO3
HNO2
CH3COOH
HClO
NH4NO3

Ka, 25°C
Large
4.5 × 10–4
1.8 × 10–5
3.2 × 10–8
5.6 × 10–10

Methyl
violet
Methyl red
Phenol red
Nitramine

B) HNO2(aq) and NaNO2(aq)
C) CH3COOH(aq) and NaCH3COO(aq)

41. Which of the following equations correctly
represents the dissolution of NH4NO3(s) in
water?
A)
NH4NO3(s)

NH4(aq) + NO3(aq)

NH4NO3(s)

NH4–(aq) + NO3+(aq)

NH4NO3(s)

NH2+(aq) + NO2–(aq) + H2O

B)

C)

Table 2 Indicator Properties
pH range

A) HClO(aq) and NaClO(aq)

D) HNO3(aq) and NaNO3(aq)

The titration of these acids with sodium hydroxide
can be done using an indicator to signal the endpoint.
Table 2 contains information about some common
acid-base indicators.

Indicator

40. Which of the following mixtures, with each
component present at a concentration of 0.1 M,
has a pH closest to 7?

Acidic
color

Basic
color

0.15–3.2

yellow

violet

4.4–6.2
6.4–8.2
10.8–
13.0

red

colorless

yellow
purple

colorless

brown

39. Which of the following solutions has the lowest
pH at 25°C?

D)
NH4NO3(s)

NH4+(aq) + NO3–(aq)

42. When 2.0 mL of 0.1 M NaOH(aq) is added to
100 mL of a solution containing 0.1 M HClO(aq)
and 0.1 M NaClO(aq), what type of change in the
pH of the solution takes place?
A) A slight (<0.1 pH unit) increase

A) 0.1 M HNO2(aq)

B) A slight (<0.1 pH unit) decrease

B) 0.1 M CH3COOH(aq)

C) A significant (>1.0 pH unit) increase

C) 0.1 M HClO(aq)

D) A significant (>1.0 pH unit) decrease

D) 0.1 M NH4NO3(aq)

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43. What is the best explanation for the fact that a
solution of NaNO2(aq) is basic?
A) NO2– is hydrolyzed with the formation of OH –
(aq) ions.
B) Na+ is hydrolyzed with the formation of OH –(aq)
ions.
C) NaNO2(aq) decreases the Ka of HNO2(aq).
D) NaNO2(aq) increases the Ka of HNO2(aq).

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Passage VIII
One can sometimes obtain a fairly good
description of a phenomenon by focusing on a few
key characteristics of a system and ignoring the
subtleties. For example, in the flow of a liquid, fairly
decent results can sometimes be obtained by ignoring
the viscosity of the liquid. (Physicist Richard
Feynman called the approximation of viscousless

water “dry water.”)
An approximate expression for the fundamental
frequency f of liquid sloshing in a tank (as in Figure
1) is given by
f = (3gH)1/2/πL
where H is the height of the liquid, L is the length of
the tank, and g denotes the acceleration due to
gravity, 10 m/s2. This equation assumes that the liquid
lacks viscosity and surface tension, and that the liquid
surface is always flat throughout the sloshing cycle.
Calculations using these simplifying assumptions
result in uncertainties of about 10%.
The sloshing modes are called seiches. They have
been observed in lakes, bays, and swimming pools.
Amplitudes of seiches in Lake Geneva in Switzerland
have been observed as large as 5 ft. A seiche in Lake
Michigan in 1954 had an amplitude of some 10 ft and
swept away several people who were fishing from
piers. Such seiches can be caused by seismic
disturbances or sudden changes in the atmospheric
pressure above one region of a lake.

44. Suppose that the atmospheric pressure suddenly
dropped at one end of a large lake, inducing a
seiche like that shown in Figure 1. The
atmospheric pressure differential between the two
ends of a lake is directly proportional to the:
A) frequency of the oscillations.
B) period of the oscillations.
C) wave speed.

D) amplitude of the oscillations.
45. The principal restoring force responsible for
maintaining the sloshing oscillations in a body
of “dry water” for which surface tension is very
small is the:
A) gravitational force.
B) viscosity of the water.
C) atmospheric pressure above the water.
D) hydrostatic pressure at the bottom of the
container.
46. Compute the period of oscillation for the
fundamental mode of a seiche induced in a lake
that averages a depth of 30 m, with a length of
6000 m over which the wave propagates.
A) 50π s
B) 200π s
C) 300π s
D) 400π s
47. The actual oscillating surface in Figure 1 would
not remain precisely flat; it would have a halfsine-wave shape. Use this fact to determine the
wavespeed v of the fundamental mode of
oscillation.
A) v = (2gH)1/2

Figure 1

The fundamental sloshing mode of a tank
of liquid. The sloshing occurs between
extremes I and III, while II denotes the
equilibrium level.

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B) v = (3gH)1/2
C) v = (3gH)1/2/π
D) v = 2(3gH)1/2/π


48. It was argued in the passage that certain
simplifying assumptions led to the equation for
frequency, which gives frequencies no more than
10% different from the observed seiche
frequencies. This equation would prove to be
greatly in error, though, for a:

50. Regarding Figure 1, which velocity profile
depicted below best shows the variation in
velocities across the air–liquid interface of II just
after I has occurred?
A)

A) container with a large width L.
B) location where the acceleration of gravity is not
10 m/s2.
C) liquid that is very viscous.

B)

D) liquid with zero surface tension.
49. Assume that a pan of “dry water” is

momentarily disturbed. Which of the following
concepts best explains why the resulting sloshing
oscillations persist for a fairly long time?

C)

A) Energy conservation
B) Momentum conservation
C) Newton’s third law
D) Archimedes’ principle

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D)


These questions are not based on a descriptive
passage and are independent of each other.

53. Which action involves more work: lifting a
weight from A to B or lowering the weight from
B to A?

51. In which of the following does sound travel most
rapidly?
A) Air (0°C)
B) Water (10°C)
C) Iron (20°C)
D) Sound travels at approximately the same speed in
all of the above.

52.

When beryllium ( Be) is bombarded with
deuterons ( H) of 10 MeV energy, a deuteron is
absorbed and a neutron is emitted. Which of the
following is formed?

A)
B)
C)
D)

Li

A) Lifting from A to B
B) Lowering from B to A
C) Equal work in both actions

Be
B
B

D) No work is required using a pulley.
54. What is the standard emf for the galvanic cell in
which the following overall reaction occurs?
2Na(s) + Cl2(g) → 2Na+(aq) + 2Cl–(aq)
Half-reaction
+
Na (aq) + e– → Na(s)
Cl2(g) + 2e– → 2Cl–(aq)

E° red
(V)
–2.71
+1.36

A) –1.35 V
B) +1.35 V
C) +4.07 V
D) +6.78 V
55. Which of the following shows the electron
configuration of chlorine in NaCl?
A) 1s22s22p63s23p4
B) 1s22s22p63s23p5
C) 1s22s22p63s23p6
D) 1s22s22p63s23p44s2
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Passage IX
Earthquake lights (EQLs) have been reported for
centuries. These lights are seen in association with
seismic activity and have been reported at distances
hundreds of kilometers from the earthquake, and
often at sea or near large bodies of water. EQLs are
usually blue or bluish-white, but yellow lights have
occasionally been reported. The source of EQLs has
not been identified, but it has recently been suggested
that they are produced by sonoluminescence (SL), the
production of light by sound waves in a liquid.

SL occurs when bubbles form in the liquid during
the rarefaction phase of a sound wave and are then
rapidly compressed during the compressional phase
of the wave. The rapid compression causes a large
increase in the temperature of the gas inside the
bubble, causing light to be emitted. Both continuum
emission, with a blackbody spectrum, and line
emission from atoms and molecules have been
observed in the laboratory from SL in water.
SL has been produced in water in the laboratory
by sound waves carrying an energy density of about
10 erg/cm3. Advancing seismic wavefronts carry a
kinetic energy density e, given by
e = 2π2ρ(A/τ)2
in which ρ is the density of the ambient medium, A is
the wave amplitude, and τ is the wave period.
Estimates of these quantities obtained from groundmotion records of earthquakes give values for e that
are often consistent with the SL hypothesis.
The SL spectrum of pure water peaks at a
wavelength of 3.10 × 10–7 m in the ultraviolet.
Dissolved salts might contribute to the yellow color.
Sodium has, in fact, a particularly strong
characteristic emission at 5.89 × 10–7 m.

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56. Which of the following statements could explain
the frequently bluish color of EQLs?
A) Sodium salts are common in the earth’s crust, and
sodium emissions can be quite bright.

B) In transparent substances, dispersion effects are in
general greater for longer wavelengths.
C) The ultraviolet radiation is absorbed by molecules
that then fluoresce at yet shorter wavelengths.
D) The ultraviolet radiation is absorbed by molecules
that then fluoresce at yet longer wavelengths.
57. During their compression, little heat is lost by
conduction from the hot vapor bubbles
responsible for SL effects because:
A) the process occurs too rapidly for heat loss to be
appreciable.
B) the heat is carried on the advancing wavefront.
C) the surrounding liquid is subjected to the same
compressional force.
D) convection predominates over other processes in
liquids at ordinary temperatures.
58. Heating of the vapor bubbles occurs during the
compression phase of the passing waves in SL
because:
A) the heat of vaporization of water is high and
serves as a barrier to the effect.
B) constructive interference in the wave motion is
greater than at other times.
C) work is being done on the vapor bubbles by
forces external to them at that time.
D) energy propagates primarily by means of
transverse waves at that time.