Page 1 of 83
ALEKS Chemistry Placement Test Study Guide | Comprehensive
Practice Questions, Verified Answers, Detailed Explanations & Latest
Exam Preparation (2026–2027)
Summarized Exam Coverage
• Matter and Properties: Definitions, states of matter, pure substances vs. mixtures, physical
and chemical properties.
• Atomic Theory and Structure: Historical models, subatomic particles (protons, neutrons,
electrons), atomic number, mass number, isotopes, ions.
• Periodic Table and Trends: Organization, groups, periods, metals/nonmetals/metalloids,
atomic radius, ionization energy, electronegativity.
• Chemical Bonding and Compounds: Ionic, covalent, polar covalent bonds, compound
naming, Lewis structures, molecular shapes, intermolecular forces.
• Chemical Reactions and Equations: Types of reactions (combustion, neutralization, etc.),
balancing equations, reaction energy.
• Stoichiometry and Math: The mole concept, molar mass, percent abundance, conversions,
gas laws, and solution dilution.
• Acids, Bases, and Nomenclature: pH scale, acid/base definitions, naming acids, polyatomic
ions, and organic prefixes.
• Quantum Mechanics and Electrons: Wave-particle duality, electron configuration, orbitals,
quantum numbers, electromagnetic spectrum.
• Nuclear Chemistry: Radioactive decay (alpha, beta, gamma), half-life.
ALEKS Chemistry Placement Test Practice Questions
1. A student measures the mass and volume of a shiny, malleable substance that conducts
electricity. Based on these properties, the substance is best classified as a(n) ______.
,Page 2 of 83
A) Nonmetal
B) Metalloid
C) Metal
D) Ionic compound
CORRECT ANSWER: C
2. A sealed flask contains a mixture of nitrogen gas and oxygen gas. Because the
components are physically combined and not chemically bonded, the contents of the flask
are a ______.
A) Compound
B) Mixture
C) Pure substance
D) Homogeneous molecule
CORRECT ANSWER: B
3. An atom of potassium becomes a cation by losing one electron. The resulting electrostatic
attraction with a nonmetal anion forms a compound through a(n) ______ bond.
A) Nonpolar covalent
B) Polar covalent
C) Hydrogen
D) Ionic
CORRECT ANSWER: D
4. A researcher discovers a new element that is brittle, dull, and a poor conductor of heat.
This element is most likely found on the right side of the periodic table and is classified
as a ______.
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A) Metal
B) Metalloid
C) Nonmetal
D) Noble gas
CORRECT ANSWER: C
5. A scientist determines the percent abundance of two isotopes of lithium. To calculate the
average atomic mass that appears on the periodic table, she must use the mass of each
isotope and its ______.
A) Atomic number
B) Half-life
C) Ionization energy
D) Percent abundance
CORRECT ANSWER: D
6. A 10.0-gram sample of a radioactive isotope decays to 5.0 grams in 12 hours. The time
required for half of the original sample to decay, known as the ______, is 12 hours.
A) Activity time
B) Radioactive window
C) Half-life
D) Decay constant
CORRECT ANSWER: C
7. According to the Pauli Exclusion Principle, two electrons in the same atomic orbital
cannot share the same spin. This means an orbital can hold a maximum of ______
electrons.
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A) One
B) Two
C) Three
D) Four
CORRECT ANSWER: B
8. During a flame test, a copper compound emits a characteristic blue-green light. This color
is part of the bright line spectrum produced as excited electrons release energy and travel
from a ______ energy level.
A) Low to high
B) Neutral to positive
C) High to low
D) Stable to unstable
CORRECT ANSWER: C
9. A student is asked to write the chemical formula for a compound formed between
aluminum and chlorine. Knowing that ionic compounds are formed from a metal and a
nonmetal, she classifies aluminum chloride as a(n) ______ compound.
A) Covalent
B) Molecular
C) Organic
D) Ionic
CORRECT ANSWER: D
10. A chemist analyzes a clear liquid and finds it contains only one kind of compound. This
liquid is classified as a pure substance, which means it contains ______ component(s).
ALEKS Chemistry Placement Test Study Guide | Comprehensive
Practice Questions, Verified Answers, Detailed Explanations & Latest
Exam Preparation (2026–2027)
Summarized Exam Coverage
• Matter and Properties: Definitions, states of matter, pure substances vs. mixtures, physical
and chemical properties.
• Atomic Theory and Structure: Historical models, subatomic particles (protons, neutrons,
electrons), atomic number, mass number, isotopes, ions.
• Periodic Table and Trends: Organization, groups, periods, metals/nonmetals/metalloids,
atomic radius, ionization energy, electronegativity.
• Chemical Bonding and Compounds: Ionic, covalent, polar covalent bonds, compound
naming, Lewis structures, molecular shapes, intermolecular forces.
• Chemical Reactions and Equations: Types of reactions (combustion, neutralization, etc.),
balancing equations, reaction energy.
• Stoichiometry and Math: The mole concept, molar mass, percent abundance, conversions,
gas laws, and solution dilution.
• Acids, Bases, and Nomenclature: pH scale, acid/base definitions, naming acids, polyatomic
ions, and organic prefixes.
• Quantum Mechanics and Electrons: Wave-particle duality, electron configuration, orbitals,
quantum numbers, electromagnetic spectrum.
• Nuclear Chemistry: Radioactive decay (alpha, beta, gamma), half-life.
ALEKS Chemistry Placement Test Practice Questions
1. A student measures the mass and volume of a shiny, malleable substance that conducts
electricity. Based on these properties, the substance is best classified as a(n) ______.
,Page 2 of 83
A) Nonmetal
B) Metalloid
C) Metal
D) Ionic compound
CORRECT ANSWER: C
2. A sealed flask contains a mixture of nitrogen gas and oxygen gas. Because the
components are physically combined and not chemically bonded, the contents of the flask
are a ______.
A) Compound
B) Mixture
C) Pure substance
D) Homogeneous molecule
CORRECT ANSWER: B
3. An atom of potassium becomes a cation by losing one electron. The resulting electrostatic
attraction with a nonmetal anion forms a compound through a(n) ______ bond.
A) Nonpolar covalent
B) Polar covalent
C) Hydrogen
D) Ionic
CORRECT ANSWER: D
4. A researcher discovers a new element that is brittle, dull, and a poor conductor of heat.
This element is most likely found on the right side of the periodic table and is classified
as a ______.
,Page 3 of 83
A) Metal
B) Metalloid
C) Nonmetal
D) Noble gas
CORRECT ANSWER: C
5. A scientist determines the percent abundance of two isotopes of lithium. To calculate the
average atomic mass that appears on the periodic table, she must use the mass of each
isotope and its ______.
A) Atomic number
B) Half-life
C) Ionization energy
D) Percent abundance
CORRECT ANSWER: D
6. A 10.0-gram sample of a radioactive isotope decays to 5.0 grams in 12 hours. The time
required for half of the original sample to decay, known as the ______, is 12 hours.
A) Activity time
B) Radioactive window
C) Half-life
D) Decay constant
CORRECT ANSWER: C
7. According to the Pauli Exclusion Principle, two electrons in the same atomic orbital
cannot share the same spin. This means an orbital can hold a maximum of ______
electrons.
, Page 4 of 83
A) One
B) Two
C) Three
D) Four
CORRECT ANSWER: B
8. During a flame test, a copper compound emits a characteristic blue-green light. This color
is part of the bright line spectrum produced as excited electrons release energy and travel
from a ______ energy level.
A) Low to high
B) Neutral to positive
C) High to low
D) Stable to unstable
CORRECT ANSWER: C
9. A student is asked to write the chemical formula for a compound formed between
aluminum and chlorine. Knowing that ionic compounds are formed from a metal and a
nonmetal, she classifies aluminum chloride as a(n) ______ compound.
A) Covalent
B) Molecular
C) Organic
D) Ionic
CORRECT ANSWER: D
10. A chemist analyzes a clear liquid and finds it contains only one kind of compound. This
liquid is classified as a pure substance, which means it contains ______ component(s).
