The PRAXIS
®
Study Companion
Chemistry
(5246)
ww
w.ets.org/praxis
The Praxis
Study Companion
2
Table of Contents
Chemistry (5246) .................................................................................................................................. 3
Test at a Glance ..................................................................................................................................................... 3
About The Test ...................................................................................................................................................... 4
Content Topics ...................................................................................................................................................... 5
Discussion Questions ............................................................................................................................................. 5
Science and Engineering Practices ...................................................................................................................... 15
Tasks of Teaching Science ................................................................................................................................... 18
Chemistry (5246) Sample Test Questions ....................................................................................... 21
Chemistry (5246) Answers .................................................................................................................................. 31
Understanding Question Types ....................................................................................................... 37
Understanding Selected-Response and Numeric-Entry Questions ..................................................................... 37
Understanding Constructed-Response Questions .............................................................................................. 38
General Assistance For The Test ...................................................................................................... 40
Praxis
®
Interactive Practice Test .......................................................................................................................... 40
Doing Your Best ................................................................................................................................................... 40
Helpful Links ........................................................................................................................................................ 40
The Praxis
Study Companion
3
Chemistry (5246)
Test at a Glance
The Praxis
®
Chemistry test is designed to measure knowledge and competencies important for
safe and effective beginning practice as a teacher of chemistry. Test takers have typically
completed a bachelor’s degree program with appropriate coursework in chemistry and
education.
Test Name Chemistry
Test Code 5246
Time 2 hours 30 minutes
Number of Questions 125 selected-response questions
Format
The test consists of a variety of selected-response questions,
where you select one or more answer choices, and other types
of questions. You can review the possible question types in
Understanding Question Types.
Test Delivery Computer Delivered
Content Categories
Approximate
Number of
Questions
Approximate
Percentage
of
Examination
I. Nature and Impact of
Science and Engineering
17 14%
II. Principles and Models of
Matter and Energy
31 25%
III. Chemical Composition,
Bonding, and Structure
25 20%
IV. Chemical Reactions and
Periodicity
29 23%
V. Solutions and Acid-Base
Chemistry
23 18%
Half or more of the questions integrate a Science and Engineering
Practice, and approximately one-quarter to one-third of the
questions assess content applied to a Task of Teaching of Science.
I.
II.
III.
IV.
V.
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About The Test
Content topics for the Chemistry test span the chemistry curriculum, including content related
to (I) Nature and Impact of Science and Engineering, (II) Principles and Models of Matter and
Energy, (III) Chemical Composition, Bonding, and Structure, (IV) Chemical Reactions and
Periodicity, and (V) Solutions and Acid Base Chemistry.
The assessment is designed and developed through work with practicing chemistry teachers,
teacher educators, and higher education chemistry specialists to reflect the science knowledge
teachers need to teach the chemistry curriculum and to reflect state and national standards,
including the National Science Teaching Association Preparation Standards for chemistry.
Content and practices measured reflect the Disciplinary Core Ideas (DCIs) and Science and
Engineering Practices (SEPs) established by the National Research Council in A Framework for
K-12 Science Education and included in the Next Generation Science Standards.
The 125 selected-response questions measure concepts, terms, phenomena, methods,
applications, data analysis, and problem solving in science. A full list of the topics covered is
provided in Content Topics.
Test takers will not need to use calculators in taking this test. The periodic table of the elements
is available as a Help screen, along with a table of information that presents various physical
constants and a few conversion factors among SI units. Whenever necessary, additional values
of physical constants are included with the text of a question.
Test takers can expect half or more of the questions on the test to integrate chemistry content
knowledge with one or more of the SEPs, listed under Science and Engineering Practices.
Test takers will also find that approximately one-quarter to one-third of the questions call for
application of chemistry content and processes within a teaching scenario or an instructional
task. Such questions—designed to measure applications of chemistry knowledge to the kinds of
decisions and evaluations a teacher must make during work with students, curriculum, and
instruction—situate chemistry content questions in tasks critical for teaching. The Tasks of
Teaching Science section has a list of tasks that are a routine part of chemistry instruction.
These tasks, identified based on research on science instruction, have been confirmed by a
national committee of teachers and teacher educators as important for effective teaching of
secondary science.
This test may contain some questions that will not count toward your score.
The Praxis
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Content Topics
This list details the topics that may be
included on the test. All test questions cover
one or more of these topics.
Discussion Questions
In this section, discussion questions are
open-ended questions or statements
intended to help test your knowledge of
fundamental concepts and your ability to
apply those concepts to classroom or real-
world situations. We do not provide
answers for the discussion questions but
thinking about the answers will help
improve your understanding of
fundamental concepts and may help you
answer a broad range of questions on the
test. Most of the questions require you to
combine several pieces of knowledge to
formulate an integrated understanding and
response. They are written to help you gain
increased understanding and facility with
the test’s subject matter. You may want to
discuss these questions with a teacher or
mentor.
I. Nature and Impact of Science and
Engineering
A. Nature of Science
1. Nature of scientific knowledge
a. Variety of investigation methods
b. Based on experimental
evidence that is reproducible
c. How major concepts develop
and change over time in light of
new evidence
d. Forming and testing hypotheses
e. Use of models, laws, and
theories to explain natural
phenomena
f. Development and application of
models to explain natural
phenomena
g. Process skills, including
observing, categorizing,
comparing, generalizing,
inferring, and concluding
2. Experimental design, data collection,
and analysis
a. Standard units of
measurement, dimensional
analysis, and unit conversion
b. Scientific notation and use of
significant figures
c. Experimental design, including
identifying variables, planning
data collection, and how it
supports testing of the
hypothesis
d. Processing, organizing, and
reporting of data
e. Error analysis, including
accuracy and precision, mean,
and percent error
f. Identifying the sources and
effects of error
g. Interpreting, extrapolating, and
drawing conclusions from data
3. Laboratory procedures
a. Appropriate preparation, use,
storage, and disposal of
materials
b. Appropriate use of laboratory
equipment (including selection,
calibration, and maintenance)
c. Safety procedures and
precautions for the laboratory
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B. Science, Engineering, Technology,
Society, and the Environment
1. Interdependence of science,
engineering, and technology
a. Engineering advances that lead
to important discoveries in
science
b. Science and technology that
drive each other forward
2. Engineering Design
a. Defining problems, including
identifying the success criteria
and the constraints
b. Designing solutions, including
proposing and evaluating in
terms of criteria, constraints,
and limitations
c. Optimizing the design, including
systematic modification and
refinement
3. Using science and engineering to
identify and address negative
impacts on the environment and
society
a. Acid rain
b. Air and water pollution
c. Greenhouse gases
d. Ozone layer depletion
e. Polymers and plastics
f. Waste disposal and recycling
4. Advantages and disadvantages
associated with various types of
energy production
a. Conservation and recycling of
energy
b. Renewable and nonrenewable
energy resources
c. Pros and cons of power
generation based on various
sources such as fossil and
nuclear fuel, hydropower, wind
power, solar power, and
geothermal power
5. Applications of chemistry and
technology in daily life
a. Water purification
b. Plastics, soap, batteries, and
other commercial products
c. Mining and industrial processes
d. Biological systems
e. Radiation in medicine and
technology
Discussion Questions: Nature and
Impact of Science and Engineering
• What are the similarities and
differences between laws,
hypotheses, and theories?
• What is the difference between
independent and dependent
variables? Describe an experiment
and identify the independent and
the dependent variables.
• Describe something in chemistry
that illustrates the relationship
between form and function.
• What is Boyle’s law and what is
Charles’s law?
• What was the role of Bohr’s model
of the atom in the development of
modern atomic theory?
• What is the uncertainty in volume
measurements made when using a
buret and how many significant
figures should be included in the
recorded volume?
• How many significant figures are in
0.1360 grams?
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• Determine the endpoint in an acid-
base titration using a plot of pH
versus the volume of base added to
an acid.
• What is the mass in grams of a
sample that has a mass of 20
milligrams?
• Express the number 0.000450 in
scientific notation.
• What is the difference between the
accuracy and the precision of a data
set?
• How do you prepare
200 mL
of
4
0.5 CaSOM
from a stock solution
of
4
2.0 CaSOM
?
• Can a very dilute solution of HCl acid
be disposed of in a sink with running
water?
• What are each of the following
pieces of equipment used for in the
laboratory: buret, pipet, Erlenmeyer
flask, and volumetric flask?
• When and why is a fume hood
needed in a chemistry laboratory?
• In what settings is solar power most
effective?
• What are the major contributors of
acid rain?
• What are some of the reactions in
the stratosphere that lead to ozone
depletion?
• What are the acid-base properties of
commonly used consumer products
such as ammonia cleaner, vinegar,
and orange juice?
• Describe the reverse osmosis
process that is sometimes used for
water purification.
• What are some examples of
nonrenewable energy resources?
II. Principles and Models of Matter and
Energy
A. Atomic and Nuclear Structure and
Processes
1. Current model of atomic structure
a. Description of basic model,
including number and location
of protons, neutrons, and
electrons
b. Quantum mechanical model of
atom, including orbitals and
subatomic particles
c. Experimental basis of model,
including gold foil experiment
and atomic spectra
2. Electron configuration of the
elements
a. Aufbau principle, Hund’s rule,
Pauli exclusion principle
b. Correlation between electron
configuration and the periodic
table
c. Relationship between electron
configuration and chemical and
physical properties of elements
3. Relationship between electronic
absorption and emission spectra
and electron energy levels in atoms
a. Electronic energy transitions in
atoms
b. Relationship between energy,
frequency, and wavelength of
electromagnetic radiation
c. Identification of atoms based on
analysis of spectra
d. Correlation of electronic
transitions to spectral lines in
electromagnetic spectrum
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4. Radioactivity
a. Characteristics of alpha
particles, beta particles, and
gamma radiation
b. Radioactive decay: include the
process, half-life, and
applications
c. Identifying fission and fusion
reactions
d. Balancing nuclear reactions and
identifying products of nuclear
reactions
B. Relationships Between Energy and
Matter in Chemistry
1. Organization of matter
a. Pure substances (elements and
compounds)
b. Mixtures (homogeneous,
heterogeneous, solutions,
suspensions)
c. States of matter (solid, liquid,
gas, and plasma)
d. Atoms, ions, molecules
2. Difference between chemical and
physical properties and changes
a. Chemical versus physical
properties
b. Chemical versus physical
changes
c. Intensive versus extensive
properties
d. Conservation of matter in
chemical processes
3. Conservation of energy
a. Conservation of energy in
chemical and physical processes
b. Kinetic and potential energy
concepts and particulate
models
c. Forms of energy including
chemical, electrical, thermal,
electromagnetic, and nuclear
d. Conversion between different
forms of energy
4. Temperature, thermal energy, and
heat capacity, including calculations
a. Temperature scales
b. Heat transfer
c. Heat capacity and specific heat
d. Calorimetry
5. Energy concepts and calculations
involving phase transitions,
including particulate and
mathematical models
a. Phase transition diagrams
b. Heats of vaporization, fusion,
and sublimation
c. Heating curves
6. Kinetic molecular theory, including
particulate and mathematical
models
a. Assumptions and applications
of the kinetic molecular theory
b. Ideal gas behavior and the ideal
gas laws
7. How thermodynamics relates to
chemical and physical processes
a. Laws of thermodynamics
b. Spontaneous (favorable) and
reversible processes
c. Changes in enthalpy, entropy,
and Gibbs energy
d. Exothermic and endothermic
processes
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e. Reaction progress diagrams
based on potential energy of
reactants and products.
f. Energy involved in breaking and
forming bonds
Discussion Questions: Principles and
Models of Matter and Energy
• How are isotopes of the same
element alike? How are they
different?
• An element has three isotopes, each
with a different mass. Explain why
the mass number for the element
that is listed on the periodic table is
not equal to the mass of any of the
isotopes.
• What are the electron configurations
for atoms of sodium and sulfur?
• Based on their electron
configurations, what is the formula
of the compound that forms in the
reaction of sodium and sulfur?
• Give an example of Hund’s rule.
• Given that the half-life of carbon-14
is 5,730 years, estimate the age of a
piece of charcoal that has a carbon-
14 content equal to 12.5% of that in
living matter.
• How is fission different than fusion
or radioactive decay?
• What is the wavelength of the
energy emitted for an electronic
transition in a hydrogen atom from
3
n
to
2n
electronic energy
level?
• In what part of the electromagnetic
spectrum are electron emission
spectral lines located?
• Test tubes contain three colorless
liquids: alcohol, water, and a weak
solution of ammonia. What
properties could be used to identify
the liquids?
• What are some examples of the
different types of mixtures?
• What is a cation?
• In their standard state, which of the
following elements are diatomic:
bromine, chlorine, argon, and
helium?
• What are some examples of
chemical properties?
• Describe a process that involves
both a chemical change and a
physical change.
• Is balancing a chemical equation an
application of the law of
conservation of energy or the law of
conservation of matter?
• List in order of increasing energy (or
decreasing wavelength) the
following forms of electromagnetic
radiation: gamma rays, microwaves,
x-rays, visible light, ultraviolet, and
infrared.
• What is an example of the
conversion of chemical energy to
electrical energy?
• Convert 350 kelvin to degrees
Celsius.
• Consider the following list: erg, joule,
electron volt, and ohm. Which of
them are units of energy?
• If a substance has high heat
capacity, will its temperature
increase faster as heat is absorbed
than will the temperature of a
substance with lower heat capacity
absorbing the same amount of
heat?
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• How much heat is absorbed as 10
grams of ice melts at the freezing
point?
• What is the boiling point of water at
high altitudes compared to that at
sea level, and why is it different?
• When a gas expands from 5 liters to
10 liters as its temperature
increases from 300 kelvin to 500
kelvin, what is the change in the
pressure of the gas?
• What are the major differences
between an ideal gas and a real gas?
• Given the heats of formation of
2
HO
,
2
CO
, and
4
CH
, calculate the
heat of combustion of
4
CH
.
• Is the combustion of
4
CH
an
exothermic or an endothermic
process?
• Based on the first and second laws
of thermodynamics, predict whether
a reaction is spontaneous.
• Describe some processes in which
the entropy of the system is
increasing.
III. Chemical Composition, Bonding,
and Structure
A. Chemical Composition
1. Mole concept and application to
chemical systems
a. Avogadro’s number, molar
mass, and mole conversions
b. Calculation of empirical and
molecular formulas
c. Percent composition
2. Systematic names and chemical
formulas for simple inorganic
compounds
a. Binary compounds
b. Acids, bases, and salts
c. Hydrates
3. Identification of common organic
functional groups and compounds
a. Alkanes, alkenes, and alkynes
b. Alcohols, ethers, ketones,
aldehydes, carboxylic acids, and
amines
B. Bonding and Structure
1. Properties and models of bonding
a. Ionic bonding
b. Covalent bonding (polar,
nonpolar, and hybridization)
c. Metallic bonding
d. Relative bond strengths and
bond lengths
2. Molecular structure models
a. Lewis structures, including
formal charges
b. Resonance structures
c. Molecular geometry (shape and
bond angles)
3. Identification of polar and nonpolar
molecules
a. Analysis of polarity of the bonds
within a molecule
b. Symmetry of molecular
structure
4. Types of interparticle interactions
a. London forces (instantaneous
induced dipole-dipole
attractions)
b. Dipole-dipole attractive forces
c. Dipole-induced dipole attractive
forces
d. Hydrogen bonding
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5. How bonding, structure, and
interparticle interactions are related
to physical properties of pure
substances
a. Boiling points and melting
points
b. Solubility
c. Equilibrium vapor pressure
Discussion Questions: Chemical
Composition, Bonding, and Structure
• What are the IUPAC names for the
following compounds:
4
HClO
,
2
CuCl
, and
42
CaSO 2H O
?
• Write the molecular formula for
each of the following compounds:
acetone, ethanol, ethanal, and
formic acid.
• Identify the functional group in each
of the following compounds:
33
CH OCH
,
32
CH NH
,
3
CH OH
, and
3
CH COOH
.
• What are the structures in the
following types of molecules that
distinguish them from other
biochemical compounds:
carbohydrates, amino acids, and
DNA?
• What is the number of moles of
oxygen atoms in 5 moles of
42
CaSO 2H O
?
• What is the molecular formula of a
compound that has the empirical
formula
24
CHO
and a molar mass of
88 grams?
• Which of the following molecules
has the shortest bond length:
HF
,
HCl
,
2
N
, or
2
O
?
• Which type of bonding is found in
each of the following solids:
KCl
,
4
NaSO
, and
Cu
?
• What is the difference between a pi
bond and a sigma bond?
• Why does a
3
NH
molecule have
trigonal pyramidal geometry?
• What are the Lewis dot and the
structural formulas for
4
CH
?
• What are the resonance structures
for the carbonate ion?
• Does
2
CO
have any polar bonds? Is
it a polar molecule? Why?
• What is the predominate
intermolecular force involved
between two
3
PCl
molecules?
• Correlate the relative boiling points
of the following molecules with their
molecular structure and
intermolecular interactions:
2
HO
,
2
Cl
,
2
Br
,
HCl
, and
2
H
.
IV. Chemical Reactions and Periodicity
A. Periodicity
1. The periodic table as a model
a. Arranged in groups and periods
b. Symbols of the element, atomic
number, and atomic mass
c. Location of metals, nonmetals,
metalloids, and transition
elements
2. Predicting and justifying patterns
and trends in physical and chemical
properties of the elements based
on their position on the periodic
table
a. Atomic and ionic radius
b. Ionization energy
c. Electron affinity
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d. Electronegativity
e. Physical properties
f. Chemical properties and
reactivity
B. Basic Principles of Chemical
Reactions
1. Balancing equations for chemical
reactions
a. Simple chemical reactions
b. Oxidation-reduction reactions
2. Stoichiometric calculations for
chemical reactions
a. Based on balanced equations
involving moles, mass, or
volume
b. Limiting reagent calculations
and percent yield
3. Predicting products of simple
reaction types
a. Combustion, neutralization,
synthesis, decomposition, and
dehydration reactions
b. Single and double replacement
reactions
4. Oxidation states and oxidation-
reduction reactions
a. Assigning oxidation numbers
b. Identifying oxidation-reduction
reactions and half-reactions
c. Standard reduction potentials
and the electrochemical
reactivity series
5. Chemical kinetics: models based on
collision theory
a. Rate laws, rate constants, and
reaction order
b. Activation energy and catalysts
6. Equilibrium in chemical systems
a. Equilibrium constants
b. Le Chatelier’s principle
Discussion Questions: Chemical
Reactions and Periodicity
• In what location of the periodic table
are nonmetals generally found?
• List some examples of transition
elements
• How do the atomic radii, ionization
energies, and melting points change
across period and down columns in
the periodic table?
• Using the location of the elements
on the periodic table, predict the
formula of the compound that
would exist containing
Mg
and
O
.
• What needs to be considered when
balancing oxidation-reduction
reactions that does not need to be
accounted for when balancing a
standard formation reaction such as
22 2
2 H + O 2 H O
?
• At standard temperature and
pressure, what is the ratio of the
volumes of hydrogen gas and
oxygen gas that react to form water?
• What is the limiting reagent in the
reaction to form water when 10
grams of hydrogen is mixed with 32
grams of oxygen?
• How is a decomposition reaction
different from a dehydration
reaction?
• What is the effect of temperature
and catalysts on reaction rates?
• How are simple rate equations
determined based on experimental
data?
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• What changes will occur to chemical
systems that are at equilibrium
when pressure or concentration of
one of the reactants or products is
changed?
• What is the effect of temperature on
equilibrium constants?
• Based on a table of standard
reduction potentials, predict
whether the following reaction will
occur spontaneously:
22
Cu+ FeCl CuCl Fe
.
• What is the oxidation state of
Mn
in
2
KMnO
?
V. Solutions and Acid-Base Chemistry
A. Solutions and Solubility
1. Analysis of types of solutions
a. Dilute, concentrated,
unsaturated, saturated, and
supersaturated
b. Identification of solute and
solvent
c. Representations of
concentration in terms of
various units, such as molarity,
mole fraction, and percent by
mass or volume
d. Calculations needed to prepare
solutions of varying
concentrations
2. Factors affecting rate of dissolving
and solubility
a. Rate of dissolving (temperature,
pressure, surface area, stirring)
b. Solubility and solubility curves
(temperature and pressure
dependence)
3. Phenomena based on colligative
properties of solutions
a. Freezing point depression and
boiling point elevation
b. Vapor pressure effect
4. Equilibrium in ionic solutions
a. Highly soluble and slightly
soluble compounds
b. Predictions of precipitation
based on the solubility product
(
sp
K
)
c. Common ion effect when
mixing ionic solutions
d. Electrolytes, nonelectrolytes,
and electrical conductivity of
solutions
B. Acid-Base Chemistry
1. Models of acids and bases and their
properties
a. Arrhenius acids and bases
b. Brønsted-Lowry acids and bases
c. Lewis acids and bases
2. The concept of pH and calculations
involving pH and
pOH
a. pH scale
b. Calculation of pH and
pOH
c. Calculation of
H
+
[]
and
[OH ]
−
3. Concepts, representations, and
calculations involving acid-base
titrations
a. Neutralization and equivalence
point
b. Use and selection of indicators
c. End point determination
d. Analysis of titrations curves
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4. Equilibrium relationships in acid-base
systems
a. Strong and weak acids and
bases
b. Monoprotic and polyprotic acids
c.
a
K
,
b
K
,
w
K
and dissociation
d. Buffer solutions
Discussion questions: Solutions and
Acid-Base Chemistry
• How many grams of solute are
present in 1.5 liters of
3
0.30 KNO
M
?
• What is the difference between a 1
molar
NaCl
solution and a 1 molal
NaCl
solution?
• Is a very concentrated solution
saturated, supersaturated, or
unsaturated? What else do you need
to know to answer the question?
• Why is ammonia gas very soluble in
water while oxygen is only slightly
soluble?
• What is the relationship between
surface area and dissolution rate?
• Will increasing temperature increase
the solubility of any substance?
• How will the vapor pressure, boiling
point, and freezing point of water
change when a nonvolatile solute is
added to water?
• Compare the degree of dissociation
of
HCl
and
2
HS
in water.
• Write a chemical equation that
illustrates the common ion effect.
• Is
4
CCl
an electrolyte?
• When an aqueous solution of
NaCl
is mixed with an aqueous solution of
3
AgNO
the precipitate
AgCl
forms.
Why?
• Select an acid that is both a
Brønsted-Lowry acid and a Lewis
acid and explain why it fits both
definitions.
• What is
[H ]
in an aqueous solution
with
pH 5.5
?
• What is the
pOH
of a solution with
8
[H ] 1 10
M

?
• Based on a titration curve,
determine the
a
pK
of the acid and
the volume of base required to
neutralize the acid.
• What indicator would be used in a
titration involving a strong acid and
a weak base and why?
• Is
HF
a strong acid? Why or why
not?
• If
23
Na CO
is dissolved in water, will
the solution be acidic, basic, or
neutral?
• For an acid
HA
,
8
a
1 10K
−
= ×
, what
is the pH of
0.001 HAM
?
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Science and Engineering
Practices
Science and Engineering Practices (SEPs)
represent eight practices that scientists and
engineers—and students and teachers—
use to investigate the world and to design
and build systems. Many test questions will
integrate one or more of these practices.
1. Asking questions (for science) and
defining problems (for engineering)
• Ask questions that arise from careful
observation of phenomena, models,
or unexpected results, to clarify
and/or seek additional information.
• Ask questions that arise from
examining models or a theory, to
clarify and/or seek additional
information and relationships.
• Ask questions to determine
relationships, including quantitative
relationships, between independent
and dependent variables.
• Ask questions to clarify and refine a
model, an explanation, or an
engineering problem.
• Ask questions that can be
investigated within the scope of the
school laboratory, research facilities,
or field (e.g., outdoor environment)
with available resources and, when
appropriate, frame a hypothesis
based on a model or theory.
• Ask and/or evaluate questions that
challenge the premise(s) of an
argument, the interpretation of a
data set, or the suitability of a
design.
• Define a design problem that can be
solved through the development of
an object, tool, process or system
and includes multiple criteria and
constraints, including scientific
knowledge that may limit possible
solutions.
2. Developing and using models
• Evaluate merits and limitations of
two different models of the same
proposed tool, process, mechanism,
or system in order to select or revise
a model that best fits the evidence
or design criteria.
• Design a test of a model to ascertain
its reliability.
• Develop, revise, and/or use a model
based on evidence to illustrate
and/or predict the relationships
between systems or between
components of a system.
• Develop and/or use multiple types
of models to provide mechanistic
accounts and/or predict
phenomena, and move flexibly
between model types based on
merits and limitations.
• Develop a complex model that
allows for manipulation and testing
of a proposed process or system.
• Develop and/or use a model
(including mathematical and
computational) to generate data to
support explanations, predict
phenomena, analyze systems,
and/or solve problems.
3. Planning and carrying out
investigations
• Plan an investigation or test a design
individually and collaboratively to
produce data to serve as the basis
for evidence as part of building and
revising models, supporting
explanations for phenomena, or
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testing solutions to problems.
Consider possible confounding
variables or effects and evaluate the
investigation’s design to ensure
variables are controlled.
• Plan and conduct an investigation
individually and collaboratively to
produce data to serve as the basis
for evidence, and in the design:
decide on types, how much, and
accuracy of data needed to produce
reliable measurements and consider
limitations on the precision of the
data (e.g., number of trials, cost, risk,
time), and refine the design
accordingly.
• Plan and conduct an investigation or
test a design solution in a safe and
ethical manner including
considerations of environmental,
social, and personal impacts.
• Select appropriate tools to collect,
record, analyze, and evaluate data.
• Make directional hypotheses that
specify what happens to a
dependent variable when an
independent variable is
manipulated.
• Manipulate variables and collect
data about a complex model of a
proposed process or system to
identify failure points or improve
performance relative to criteria for
success or other variables.
4. Analyzing and interpreting data
• Analyze data using tools,
technologies, and/or models (e.g.,
computational, mathematical) in
order to make valid and reliable
scientific claims or determine an
optimal design solution.
• Apply concepts of statistics and
probability (including determining
function fits to data, slope, intercept,
and correlation coefficient for linear
fits) to scientific and engineering
questions and problems, using
digital tools when feasible.
• Consider limitations of data analysis
(e.g., measurement error, sample
selection) when analyzing and
interpreting data.
• Compare and contrast various types
of data sets (e.g., self-generated,
archival) to examine consistency of
measurements and observations.
• Evaluate the impact of new data on
a working explanation and/or model
of a proposed process or system.
• Analyze data to identify design
features or characteristics of the
components of a proposed process
or system to optimize it relative to
criteria for success.
5. Using mathematics and
computational thinking
• Create and/or revise a
computational model or simulation
of a phenomenon, designed device,
process, or system.
• Use mathematical, computational,
and/or algorithmic representations
of phenomena or design solutions
to describe and/or support claims
and/or explanations.
• Apply techniques of algebra and
functions to represent and solve
scientific and engineering problems.
• Use simple limit cases to test
mathematical expressions,
computer programs, algorithms, or
simulations of a process or system
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to see if a model “makes sense” by
comparing the outcomes with what
is known about the real world.
• Apply ratios, rates, percentages, and
unit conversions in the context of
complicated measurement
problems involving quantities with
derived or compound units (such as
mg/mL
,
3
kg/m
, acre-feet, etc.).
6. Constructing explanations (for
science) and designing solutions (for
engineering)
• Make a quantitative and/or
qualitative claim regarding the
relationship between dependent
and independent variables.
• Construct and revise an explanation
based on valid and reliable evidence
obtained from a variety of sources
(including students’ own
investigations, models, theories,
simulations, peer review) and the
assumption that theories and laws
that describe the natural world
operate today as they did in the past
and will continue to do so in the
future.
• Apply scientific ideas, principles,
and/or evidence to provide an
explanation of phenomena and
solve design problems, taking into
account possible unanticipated
effects.
• Apply scientific reasoning, theory,
and/or models to link evidence to
the claims to assess the extent to
which the reasoning and data
support the explanation or
conclusion.
• Design, evaluate, and/or refine a
solution to a complex real-world
problem, based on scientific
knowledge, student-generated
sources of evidence, prioritized
criteria, and tradeoff considerations.
7. Engaging in argument from evidence
• Compare and evaluate competing
arguments or design solutions in
light of currently accepted
explanations, new evidence,
limitations (e.g., trade-offs),
constraints, and ethical issues.
• Evaluate the claims, evidence,
and/or reasoning behind currently
accepted explanations or solutions
to determine the merits of
arguments.
• Respectfully provide and/or receive
critiques on scientific arguments by
probing reasoning and evidence and
challenging ideas and conclusions,
responding thoughtfully to diverse
perspectives, and determining what
additional information is required to
resolve contradictions.
• Construct, use, and/or present an
oral and written argument or
counter-arguments based on data
and evidence.
• Make and defend a claim based on
evidence about the natural world or
the effectiveness of a design
solution that reflects scientific
knowledge, and student-generated
evidence.
• Evaluate competing design solutions
to a real-world problem based on
scientific ideas and principles,
empirical evidence, and/or logical
arguments regarding relevant
factors (e.g. economic, societal,
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environmental, ethical
considerations).
8. Obtaining, evaluating, and
communicating information
• Critically read scientific literature
adapted for classroom use to
determine the central ideas or
conclusions and/or to obtain
scientific and/or technical
information to summarize complex
evidence, concepts, processes, or
information presented in a text by
paraphrasing them in simpler but
still accurate terms.
• Compare, integrate and evaluate
sources of information presented in
different media or formats (e.g.,
visually, quantitatively) as well as in
words in order to address a
scientific question or solve a
problem.
• Gather, read, and evaluate scientific
and/or technical information from
multiple authoritative sources,
assessing the evidence and
usefulness of each source.
• Evaluate the validity and reliability of
and/or synthesize multiple claims,
methods, and/or designs that
appear in scientific and technical
texts or media reports, verifying the
data when possible.
• Communicate scientific and/or
technical information or ideas (e.g.
about phenomena and/or the
process of development and the
design and performance of a
proposed process or system) in
multiple formats (including orally,
graphically, textually, and
mathematically).
Tasks of Teaching Science
This list includes instructional tasks that
teachers engage in that are essential for
effective Chemistry teaching. Many test
questions will measure content through
application to one or more of these tasks.
Scientific Instructional Goals, Big Ideas,
and Topics
1. Selecting or sequencing appropriate
instructional goals or big ideas for a
topic
2. Identifying the big idea or
instructional goal of an instructional
activity
3. Choosing which science ideas or
instructional activities are most
closely related to a particular
instructional goal
4. Linking science ideas to one another
and to particular activities, models,
and representations within and
across units
Scientific Investigations and
Demonstrations
5. Selecting investigations or
demonstrations, including virtual,
that facilitate understanding of
disciplinary core ideas, scientific
practices, or crosscutting concepts
6. Evaluating investigation questions for
quality (e.g., testable, empirical)
7. Determining the variables,
techniques, or tools that are
appropriate for use by students to
address a specific investigation
question
8. Critiquing scientific procedures, data,
observations, or results for their
quality, accuracy, or appropriateness
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9. Supporting students in generating
questions for investigation or
identifying patterns in data and
observations
Scientific Resources (texts, curriculum
materials, journals, and other print and
media-based resources)
10. Evaluating instructional materials
and other resources for their ability
to address scientific concepts;
engage students with relevant
phenomena; develop and use
scientific ideas; promote students’
thinking about phenomena,
experiences, and knowledge; take
account of students’ ideas and
background; and assess student
progress
11. Choosing resources that support the
selection of accurate, valid, and
appropriate goals for science
learning
Student Ideas (including common
misconceptions, alternate conceptions,
and partial conceptions)
12. Analyzing student ideas for common
misconceptions regarding intended
scientific learning
13. Selecting diagnostic items and
eliciting student thinking about
scientific ideas and practices to
identify common student
misconceptions and the basis for
those misconceptions
14. Developing or selecting instructional
moves, approaches, or
representations that provide
evidence about common student
misconceptions and help students
move toward a better understanding
of the idea, concept, or practice
Scientific Language, Discourse,
Vocabulary, and Definitions
15. Selecting scientific language that is
precise, accurate, grade-appropriate,
and illustrates key scientific concepts
16. Anticipating scientific language and
vocabulary that may be difficult for
students
17. Modeling the use of appropriate
verbal and written scientific language
in critiquing arguments or
explanations, in describing
observations, or in using evidence to
support a claim, etc.
18. Supporting and critiquing students’
participation in and use of verbal and
written scientific discourse and
argumentation
Scientific Explanations (includes claim,
evidence, and reasoning)
19. Critiquing student-generated
explanations or descriptions for their
generalizability, accuracy, precision,
or consistency with scientific
evidence
20. Selecting explanations of natural
phenomena that are accurate and
accessible to students
Scientific Models and Representations
(analogies, metaphors, simulations,
illustrations, diagrams, data tables,
performances, videos, animations,
graphs, and examples)
21. Evaluating or selecting scientific
models and representations that
predict or explain scientific
phenomena or address instructional
goals
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22. Engaging students in using,
modifying, creating, and critiquing
scientific models and representations
that are matched to an instructional
goal
23. Evaluating student models or
representations for evidence of
scientific understanding
24. Generating or selecting diagnostic
questions to evaluate student
understanding of specific models or
representations
25. Evaluating student ideas about what
makes for good scientific models and
representations
The Praxis
Study Companion
Chemistry (5246) Sample Test Questions
The sample questions that follow represent a number of the types of questions and topics that
appear on the test. They are not, however, representative of the entire scope of the test in
either content or difficulty. Answers with explanations follow the questions.
Directions: Each of the questions or incomplete statements below is followed by suggested
answers or completions. Select the one that is best in each case.
1. Completely dry crystals of an unknown inorganic compound were heated in a clean, dry
glass test tube. The total mass of the test tube and its solid contents was measured before
and after heating. After heating, the total mass was observed to be less. Which TWO of the
following could explain the observation?
(A) The crystals were a hydrate, and some of the water vaporized.
(B) The crystals were a compound that decomposed into two different solid compounds.
(C) A reaction occurred in which one of the products was a gas.
(D) The crystals were a compound that reacted with oxygen in the air to form a single
compound of lower mass than the original compound.
2. Which TWO of the following processes involve a decrease in entropy?
(A) Water freezing
(B) Snow subliming
(C) Dew forming on grass
(D) Sugar dissolving in water
3 2 32
Pt(NH )Cl ( ) + Br ( ) Pt(NH ) ClBr( ) + Cl ()aq aq aq aq

3. For an upcoming lab activity, a teacher asks students to identify variables that should be
controlled when six different trials are done to determine the rate of disappearance of
Br
in the preceding chemical reaction. Which THREE of following student responses are
correct?
(A) Concentration of
Cl
(B) Temperature
(C) Initial amount of
32
Pt(NH )Cl ( )aq
(D) Initial volume of the reaction mixture
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4. In which of the following compounds do molecules interact through London dispersion
forces only?
(A)
2
HO
(B)
4
CF
(C)
3
CH Cl
(D)
CO
5. Of the following, which best describes a solution with
pOH = 12.0
at
25 C
?
(A) An acidic solution that will turn blue litmus paper red because
2
[H ] 1.0 10 M

(B) An acidic solution that will turn red litmus paper blue because
2
[H ] 1.0 10 M

(C) A basic solution that will turn red litmus paper blue because
12
[H ] 1.0 10 M

(D) A basic solution that will turn blue litmus paper red because
12
[H ] 1.0 10 M


44
CuSO Zn ZnSO Cu
6. Which of the following species is reduced in the preceding oxidation-reduction reaction?
(A)
Zn
(B)
2
Cu
(C)
6
S
(D)
2
O
7. Based on its position on the periodic table, which of the following has the largest atomic
radius?
(A)
Cs
(B)
Mg
(C)
I
(D)
Se
The Praxis
Study Companion
8. If
50 mL
of
24
0.02 Na SOM
is diluted with sufficient water to make a total volume of
200 mL
, which of the following is the concentration of
Na
ions in the diluted solution?
(A)
0.005 M
(B)
0.01 M
(C)
0.02 M
(D)
0.04 M
9. Of the following, which best describes smoke?
(A) A suspension
(B) An alloy
(C) A solution
(D) A homogeneous mixture
10. Which of the following is the ground-state electron configuration of
2
Mg
?
(A)
22 6
12 2ssp
(B)
22 62
12 2 3
ssps
(C)
22 62 6
12 2 3 3sspsp
(D)
22 62 62
12 2 3 3 4sspsps
11. How many oxygen atoms are in two moles of
4
CuSO
?
(A) 4
(B) 8
(C)
23
6.02 10
(D)
24
4.82 10
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12. If a
20 g
sample of a substance is compared to a
10 g
sample of the same substance, both
at
25 C
, the
20 g
sample will have a higher
(A) density
(B) thermal heat content
(C) temperature
(D) boiling point
13. A well-designed experiment always includes which of the following?
(A) A scientific law
(B) A well-written conclusion
(C) Multiple independent variables
(D) A plan about how to measure the dependent variable
14. If a weak acid is titrated with a strong base, which of the following could be the pH at the
equivalence point?
(A) 2.0
(B) 6.0
(C) 7.0
(D) 8.0
15. Of the following molecules, which has the most polar covalent bonds?
(A)
HBr
(B)
4
CH
(C)
2
Cl
(D)
2
H
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Study Companion
16. At standard temperature and pressure, what volume of
2
CO
is produced when
1.000 mol
of
8 18
CH
undergoes complete combustion?
(A)
8.00 L
(B)
22.4 L
(C)
89.6 L
(D)
179.2 L
17. Ozone in the atmosphere is most closely related to which of the following?
(A) Acid rain production
(B) Water pollution
(C) Absorption of ultraviolet radiation in the stratosphere
(D) Nuclear power plant waste
18. Which of the following is a carboxylic acid?
(A)
32
CH CH COOH
(B)
33
CH OCH
(C)
32
CH CH OH
(D)
32
CH NH
19. For
2
Mg(OH)
at room temperature, the solubility product
sp
K
is approximately
12
7 10
.
The magnitude of the solubility constant indicates which of the following about
2
Mg(OH)
?
(A) If sufficient
2
Mg(OH)
is mixed with water, it can form
2
11 Mg(OH) ( )
M aq
.
(B) It cannot form a saturated solution.
(C) It is a weak acid.
(D) It is only slightly soluble.
The Praxis
Study Companion

2 22 2
MnO 4 HCl MnCl Cl 2 H O
20. Based on the preceding balanced equation, what is the maximum number of moles of
2
Cl
that can be produced if
2.0 mol
of
2
MnO
and
6.0 mol
of
HCl
are initially provided in a
reaction vessel?
(A)
1.0 mol
(B)
1.5 mol
(C)
2.0 mol
(D)
4.0 mol
21. The elements
F
,
Cl
,
Br
and
I
all form compounds with
Na
and are in the same column of
the periodic table. The elements in this group are known as
(A) transition elements
(B) alkaline earth metals
(C) noble gases
(D) halogens
22. Which of the following is a balanced equation for a chemical reaction?
(A)
22
2 K + 2 H O 2 KOH + H
(B)
2
Mg + O 2 MgO
(C)
24 4 2
NaOH + H SO NaSO + H O
(D)
22
Cl + NaI NaCl + I
23. In an experiment to investigate the photoelectric effect, a clean surface of a certain metal
was illuminated with light of different but sufficiently high frequencies. This resulted in
electrons being emitted from the surface of the metal. The kinetic energy of the emitted
electrons varied with the frequency of the incident light. Which of the following is the
dependent variable in the experiment?
(A) Atomic number of the metal
(B) Atomic mass of the metal
(C) Frequency of the incident light
(D) Kinetic energy of the emitted electrons
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Study Companion
22
2 AB() A() + B()g gg
24. The preceding reaction is at equilibrium. Which of the following is true if the volume of the
reaction vessel is decreased?
(A) The partial pressure of
AB
will decrease.
(B) The partial pressure of both
2
A
and
2
B
will decrease.
(C) The total pressure of the system will remain constant.
(D) The decrease in volume will have no effect on the equilibrium.
25. Of the following
0.05 M
aqueous solutions, which is most likely to have the lowest freezing
point?
(A)
KBr
(B)
CsI
(C)
2
MgCl
(D)
3
CH OH
The Praxis
Study Companion
Compound
a
K
HOCN
4
3.5 10
4
HIO
2
2.2 10
2
ClCH COOH
3
1.4 10
66
C H COOH
5
6.3 10
26. A teacher asks students to use the data in the preceding table to identify the strongest acid
among the weak acids listed and explain their choice. A student says that
66
C H COOH
is the
strongest acid because it has the smallest
a
K
. Of the following, which statement, if true,
would best help correct the student's misconception?
(A) In general, an acid that contains a
Cl
atom in its chemical formulas is a strong acid,
regardless of the value of its
a
K
.
(B) In general, an acid that contains a large number of atoms is a very weak acid, regardless
of the value of its
a
K
.
(C) The acid with the largest value for
a
K
is the strongest acid because the
a
K
indicates the
degree to which the acid dissociates.
(D) The acid with the smallest value for its
a
K
will dissociate to the largest degree and
therefore be a very weak acid.
27. Which of the following molecules is nonpolar?
(A)
4
CCl
(B)
2
HO
(C)
HF
(D)
CO
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Study Companion
28. Which of the following gases is produced when concentrated aqueous
HF
is added to an
aqueous solution of
23
Na CO
?
(A)
2
CO
(B)
2
O
(C)
2
H
(D)
2
Cl
232
Th X + alpha particle
29. When a thorium-232 atom emits an alpha particle, as represented in the preceding
equation, which of the following is
X
?
(A)
228
Th
(B)
230
Ac
(C)
228
Ra
(D)
230
Rn
30. Which of the following is an exothermic change of state?
(A) Solid to liquid
(B) Liquid to gas
(C) Gas to solid
(D) Solid to gas
31. Based on the valence shell electron pair repulsion (VSEPR) model, which of the following
gives the approximate bond angles about the carbon atom in a
4
CCl
molecule?
(A)
30
(B)
45
(C)
90
(D)
109.5
The Praxis
Study Companion
32. Which of the following compounds contained in some beverages is a strong electrolyte?
(A) Sucrose
(B) Citric acid
(C) Starch
(D) Sodium chloride
The Praxis
Study Companion
Chemistry (5246) Answers
1. Options (A) and (C) are correct. The
correct answers are (A) and (C). Inorganic
hydrates are compounds that in their
solid state contain some water molecules
within their crystal lattice. When heated,
the water can vaporize, resulting in a
lower mass for the remaining solid. An
example of a hydrate is
32
MgCO 5H O
.
When a reaction occurs in an open vessel
in which one of the products is a gas, the
gas can escape, resulting in a loss of mass.
A decomposition reaction that produced
two solid compounds would NOT result in
a loss of mass. If an oxide had been
produced in a reaction with oxygen, the
mass of the contents would have
increased, NOT decreased.
Content
I A
Science and Engineering
7
Task of Teaching
20
2. Options (A) and (C) are correct.
Entropy decreases as liquid water
becomes solid water and as water vapor
condenses on grass as dew. Entropy
increases as snow changes to gaseous
water as it sublimates and as sugar
dissolves in water.
Content
II B
3. Options (B), (C) and (D) are correct.
The rate of a chemical reaction depends
on the temperature and can also depend
on the concentrations of the reactants.
To determine the rate with respect to
Br
, the concentration of
32
Pt(NH )Cl ( )
aq
must be kept constant. Hence, the initial
volume of the reaction mixture must also
be kept constant to avoid changes in
concentration of
32
Pt(NH )Cl ( )aq
.
Content
IV B
Science and Engineering
3
Task of Teaching
7
4. Option (B) is correct.
4
CF
molecules
interact through London dispersion
forces only because they are nonpolar
molecules. The other three compounds
consist of polar molecules that can
interact by dipole-dipole interactions and
2
HO
molecules can also interact through
hydrogen bonding.
Content
III B
The Praxis
Study Companion
5.
Option (A) is correct.
pOH log[OH ]
for an aqueous
solution. Hence,
12
[OH ] 1.0 10 M

if
pOH 12.0
. At
25 C
,
14
w
[H ][OH ] 1.0 10K

. Based on
this relationship,

14
2
12
1.0 10
[H ] 1.0 10
1.0 10
. Since
2
pH log[H ] log(1 10 ) 2.0


pH,
the solution is acidic and will turn blue
litmus paper red.
Content
V B
Science and Engineering
6
6. Option (B) is correct. Reduction
involves gaining electrons which results in
a reduction of the oxidation number of
the species.
2
Cu
in
4
CuSO
is reduced to
Cu
, with oxidation number of 0.
Zn
, with
oxidation number of 0, loses electrons
and is oxidized to
2
Zn
in
4
ZnSO
.
6
S
and
2
O
do not undergo a change in
oxidation number during the reaction.
Content
IV B
Science and Engineering
2
7. Option (A) is correct. An atom of
Cs
has a radius that is larger than the radius
of an atom of
Mg
,
I
, or
Se
based on the
location of
Cs
on the periodic table.
Going down a column, the atomic radius
generally increases, and going from left
to right across a row, the atomic radius
generally decreases.
Cs
is located near
the lower corner on the left side of the
periodic table.
Content
IV A
Science and Engineering
2
8. Option (B) is correct. The
concentration of
Na
ions is
0.01 M
, and
it is found from

24
24
0.05 L 0.02 Na SO
2 Na
0.10
0.2 L Na SO
M
M
,
where
50 mL 0.05 L
and
200 mL 0.2 L
.
Content
V A
Science and Engineering
5
9. Option (A) is correct. Smoke is a
suspension. Tiny particles are
temporarily suspended in the air as they
are randomly moving as a result of
collisions with molecules of nitrogen,
oxygen, and other gases. Eventually, the
particles may settle and collect on
surfaces.
Content
II B
Science and Engineering
15
The Praxis
Study Companion
10.
Option (A) is correct.
The electron
configuration for the
2
Mg
ion based on
the Aufbau principle is
22 6
12 2
ssp
.
Mg
atoms each have 12 electrons, but
2
Mg
ions each have 10 electrons.
Content
II A
Science and Engineering
2
Task of Teaching
21
11. Option (D) is correct. Two moles of
4
CuSO
contain 8 moles of oxygen atoms.
The number of oxygen atoms is equal to

23 24
8 6.02 10 4.82 10
oxygen
atoms.
Content
III A
Science and Engineering
5
12. Option (B) is correct. The
20 g
sample will have a higher thermal heat
content because heat content depends on
both the temperature and the amount of
the substance. Since both samples contain
the same substance, they will have the
same density, temperature, and boiling
point.
Content
II B
13. Option (D) is correct. The
experimental design should have only one
independent variable and should include
a procedure.
Content
I A
Science and Engineering
3
Task of Teaching
7
14. Option (D) is correct. The pH at the
equivalence point for a titration of a
weak acid with a strong base will not be
at 7.0 but will be greater than 7.0
because the hydrolysis of the salt of the
weak acid will produce
OH
ions,
resulting in the formation of a basic
solution. An example is the titration of
the weak acid
3
CH COOH
with the strong
base
NaOH
. At the equivalence point of
the titration,
Na
,
3
CH COO
, and
2
HO
have been produced. But there is a
hydrolysis equilibrium that exists:
3 23
CH COO H O CH COOH OH


.
Hence, the pH will be greater than 7.0.
Content
V B
15. Option (A) is correct. Since the
difference in electronegativity between
H
and
Br
is greater than the difference
in electronegativity between
C
and
H
,
the covalent bond between
H
and
Br
in
HBr
is more polar than the covalent
bonds between
C
and
H
in
4
CH
. There
is a nonpolar bond in
2
Cl
and in
2
H
.
Content
III B
The Praxis
Study Companion
16.
Option (D) is correct.
The balanced
equation for the complete combustion
reaction is
8 18 2 2 2
2 C H 25 O 16 CO 18 H O
.
Based on the balanced equation,
8 mol
of
2
CO
would be produced. The volume of
8 mol
of
2
CO
at standard temperature
and pressure is approximately
8 22.4 L 179.2 L
.
Content
II B
Science and Engineering
5
17. Option (C) is correct. Ozone absorbs
harmful ultraviolet radiation in the
stratosphere.
Content
I B
18. Option (A) is correct. Carboxylic acids
include the carboxyl functional group,
which contains a carbonyl group bonded
to a hydroxyl group. Answer choice (B) is
an ether, answer choice (C) is carbonic
acid, and answer choice (D) is an amine.
Content
III A
Science and Engineering
15
19. Option (D) is correct. A very low
sp
K
indicates that
2
Mg(OH)
is only slightly
soluble and can form a saturated solution
that will have a very small concentration
of
2
Mg
ions and
OH
ions present in
solution. Hence, an
11M
solution cannot
be prepared. It is a base, not an acid.
Content
V A
Science and Engineering
7
Task of Teaching
20
20. Option (B) is correct. Based on the
balanced equation, the maximum
possible number of moles of
2
Cl
that can
be produced is
1.5 mol
. This is found
from
2
2
1 m o l C l
6 mol HCl 1.5 mol Cl
4 mol HCl

.
In this case,
2
MnO
is in excess and
HCl
is the limiting reagent, since to use up all
the
2.0 mol
of
2
MnO
would require
8.0 mol
of
HCl
.
Content
III B
Science and Engineering
5
21. Option (D) is correct.
F
,
Cl
,
Br
, and
I
are nonmetals in a group called the
halogens and are found in the next-to-
last column of the periodic table.
Transition elements are metals located in
columns 3 through 12 in rows in the
middle of the periodic table, starting in
row 4. The alkaline earth metals are in
the second column of the periodic table.
The noble gases are located in the last
column of the periodic table.
Content
IV A
Science and Engineering
2
The Praxis
Study Companion
22.
Option (A) is correct.
22
2 K + 2 H O 2 KOH + H
is a balanced
equation for a chemical reaction because
it has an equal number of atoms of each
element in the reactants and in the
products. The other response choices are
unbalanced chemical reaction equations.
Content
III B
Science and Engineering
2
23. Option (D) is correct. The kinetic
energy of the emitted electrons is the
dependent variable because the kinetic
energy varied as the independent variable
changed. The frequency of the incident
light is the independent variable. As
different frequencies of light are used, the
kinetic energy of the emitted electrons will
be different. The atomic number and
atomic mass were not variables that
changed during the experiment, since one
particular metal was used.
Content
II A
Science and Engineering
1
24. Option (D) is correct. Although the
total pressure will increase, the decrease
in volume will have no effect on the
equilibrium because there is an equal
number of moles of gas on the reactant
side and the product side of the reaction
equation.
Content
IV B
Science and Engineering
6
25. Option (C) is correct. Based on
colligative properties,
2
MgCl
will have
the lowest freezing point. Assuming
complete dissociation, it will form three
particles per formula unit, one
2
Mg
ion
and two
Cl
ions. Assuming complete
dissociation,
KBr
and
CsI
will each form
only two particles per formula unit.
3
CH OH
has an extremely low ability to
dissociate in water to form
H
and
3
CH O
ions, and thus has a total of
approximately one particle per formula
unit.
Content
V A
Science and Engineering
5
26. Option (C) is correct. The student’s
assertion that
66
C H COOH
is the
strongest acid of those listed is incorrect.
The teacher can help correct the
student’s misconception by explaining
that the strongest acid is the one with
the highest degree of dissociation. Since
all of the acids are monoprotic, and can
be represented by
HA
, the
a
K
will
indicate the degree of dissociation since
a
[H ][A ]
[HA]
K

.
Content
V B
Science and Engineering
4
Task of Teaching
14
The Praxis
Study Companion
27.
Option (A) is correct.
All of the compounds are composed of molecules with polar
bonds. But based on a symmetrical tetrahedral molecular geometry,
4
CCl
is a nonpolar
molecule with a net dipole moment of zero.
2
HO
is a polar molecule with bent molecular
geometry and a nonzero net dipole moment, and
HF
and
CO
are each polar molecules with
linear molecular geometry and a nonzero net dipole moment.
Content
III B
28. Option (A) is correct. The reaction will produce
2
CO
. The reaction is
23 2 2
Na CO ( ) 2 HCl( ) CO ( ) 2 NaCl( ) H O( )aq aq aq aq l 
.
Content
IV B
29. Option (C) is correct. The nucleus of thorium-232 contains 90 protons and can be
represented by
232
90
Th
, which undergoes a radioactive decay and emits an alpha particle as
represented in the balanced nuclear equation
232 228 4
90 88 2
Th Ra He
. An alpha particle is a
helium nucleus and is represented by
4
2
He
. To balance the nuclear equation, X must have 88
protons and a mass number of 228. Thus, X is
228
88
Ra
.
Content
II A
Science and Engineering
2
30. Option (C) is correct. When a gas is converted to a solid, the process is exothermic
because energy is released. The conversion of a solid to a liquid and the conversion of a
liquid to a gas both involve the absorption of energy and are endothermic processes.
Content
II B
31. Option (D) is correct. Based on the valence shell electron pair repulsion (VSEPR) model,
the bond angles about a central carbon atom in a
4
CCl
molecule are
109.5
because
4
CCl
is
predicted to have a tetrahedral molecular geometry.
Content
III B
Science and Engineering
2
32. Option (D) is correct. Of the compounds listed, only sodium chloride is a strong
electrolyte, which means that it undergoes a high degree of dissociation in aqueous
solutions. Sucrose is a nonelectrolyte, some starches are weak electrolytes, and citric acid is
a weak electrolyte.
Content
I B
The Praxis
Study Companion
Understanding Question Types
The Praxis
®
assessments include a variety of question types: constructed response (for which
you write a response of your own); selected response, for which you select one or more
answers from a list of choices or make another kind of selection (e.g., by selecting a sentence in
a text or by selecting part of a graphic); and numeric entry, for which you enter a numeric value
in an answer field. You may be familiar with these question formats from taking other
standardized tests. If not, familiarize yourself with them so you don’t spend time during the test
figuring out how to answer them.
Understanding Selected-Response and Numeric-Entry Questions
For most questions, you respond by selecting an oval to select a single answer from a list of
answer choices.
However, interactive question types may also ask you to respond by:
• Selecting more than one choice from a list of choices.
• Typing in a numeric-entry box. When the answer is a number, you may be asked to
enter a numerical answer. Some questions may have more than one entry box to enter
a response. Numeric-entry questions typically appear on mathematics-related tests.
• Selecting parts of a graphic. In some questions, you will select your answers by selecting
a location (or locations) on a graphic such as a map or chart, as opposed to choosing
your answer from a list.
• Selecting sentences. In questions with reading passages, you may be asked to choose
your answers by selecting a sentence (or sentences) within the reading passage.
• Dragging and dropping answer choices into targets on the screen. You may be asked to
select answers from a list of choices and to drag your answers to the appropriate
location in a table, paragraph of text or graphic.
• Selecting answer choices from a drop-down menu. You may be asked to choose
answers by selecting choices from a drop-down menu (e.g., to complete a sentence).
Remember that with every question you will get clear instructions.
The Praxis
Study Companion
Understanding Constructed-Response Questions
Some tests include constructed-response questions, which require you to demonstrate your
knowledge in a subject area by writing your own response to topics. Essays and short-answer
questions are types of constructed-response questions.
For example, an essay question might present you with a topic and ask you to discuss the
extent to which you agree or disagree with the opinion stated. You must support your position
with specific reasons and examples from your own experience, observations, or reading.
Review a few sample essay topics:
• Brown v. Board of Education of Topeka
“We come then to the question presented: Does segregation of children in public
schools solely on the basis of race, even though the physical facilities and other
‘tangible’ factors may be equal, deprive the children of the minority group of equal
educational opportunities? We believe that it does.”
A. What legal doctrine or principle, established in Plessy v. Ferguson (1896), did the
Supreme Court reverse when it issued the 1954 ruling quoted above?
B. What was the rationale given by the justices for their 1954 ruling?
• In his self-analysis, Mr. Payton says that the better-performing students say small-group work
is boring and that they learn more working alone or only with students like themselves.
Assume that Mr. Payton wants to continue using cooperative learning groups because he
believes they have value for all students.
o Describe TWO strategies he could use to address the concerns of the students
who have complained.
o Explain how each strategy suggested could provide an opportunity to improve
the functioning of cooperative learning groups. Base your response on principles
of effective instructional strategies.
• “Minimum-wage jobs are a ticket to nowhere. They are boring and repetitive and teach
employees little or nothing of value. Minimum-wage employers take advantage of people
because they need a job.”
o Discuss the extent to which you agree or disagree with this opinion. Support
your views with specific reasons and examples from your own experience,
observations, or reading.
The Praxis
Study Companion
Keep these things in mind when you respond to a constructed-response question:
1. Answer the question accurately. Analyze what each part of the question is asking you
to do. If the question asks you to describe or discuss, you should provide more than just
a list.
2. Answer the question completely. If a question asks you to do three distinct things in
your response, you should cover all three things for the best score. Otherwise, no
matter how well you write, you will not be awarded full credit.
3. Answer the question that is asked. Do not change the question or challenge the basis
of the question. You will receive no credit or a low score if you answer another question
or if you state, for example, that there is no possible answer.
4. Give a thorough and detailed response. You must demonstrate that you have a
thorough understanding of the subject matter. However, your response should be
straightforward and not filled with unnecessary information.
5. Take notes on scratch paper so that you don’t miss any details. Then you’ll be sure to
have all the information you need to answer the question.
6. Reread your response. Check that you have written what you thought you wrote. Be
sure not to leave sentences unfinished or omit clarifying information.
The Praxis
Study Companion
General Assistance For The Test
Praxis
®
Interactive Practice Test
This full-length Praxis
®
practice test lets you practice answering one set of authentic test
questions in an environment that simulates the computer-delivered test.
• Timed just like the real test
• Correct answers with detailed explanations
• Practice test results for each content category
You can learn more and purchase the practice test here
.
Doing Your Best
Strategy and Success Tips
Effective Praxis test preparation doesn’t just happen. You'll want to set clear goals and
deadlines for yourself along the way. Learn from the experts. Get practical tips to help you
navigate your Praxis test and make the best use of your time. Learn more at
Strategy and Tips
for Taking a Praxis Test.
Develop Your Study Plan
Planning your study time is important to help ensure that you review all content areas covered
on the test. View a sample plan and learn how to create your own. Learn more at Develop a
Study Plan.
Helpful Links
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The Praxis
Study Companion
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