PORTAGE LEARNING CHEM 103 GENERAL CHEMISTRY I [CHEMISTRY 103]
COMPREHENSIVE EXAM PRACTICE & ACTUAL STUDY GUIDE — FULL TESTBANK:
150 ADVANCED PRACTICE QUESTIONS & 100% CORRECT ANSWERS WITH
RATIONALES — 2026/2027 LATEST UPDATE
TABLE OF CONTENTS
i. Atomic Structure, Isotopes, and Periodic Trends
ii. Chemical Bonding, Lewis Structures, and Molecular Geometry
iii. Stoichiometry, Chemical Reactions, and Limiting Reactants
iv. Gases, Liquids, Solids, and Intermolecular Forces
v. Thermochemistry and Energy Changes
vi. Quantum Theory, Electron Configuration, and Periodic Properties
vii. Solutions, Concentrations, and Colligative Properties
viii. Acids, Bases, pH, and Chemical Equilibrium
ix. Redox Chemistry and Electrochemical Principles
x. Advanced Integrated General Chemistry Applications
DESCRIPTION
This comprehensive Portage Learning CHEM 103 General Chemistry I practice
resource is designed to strengthen advanced understanding across the major
principles of introductory general chemistry. It emphasizes quantitative problem
solving, molecular interpretation, chemical reasoning, reaction analysis,
thermochemistry, atomic structure, bonding, gases, solutions, acids and bases, and
equilibrium. The questions are intentionally challenging and appropriate for students
seeking rigorous examination preparation, including college and advanced-level
chemistry learners. Students should expect 100+ questions and answers with a
rationale, realistic distractors, calculations, conceptual applications, and analytical
scenarios designed to expose common misconceptions. Purchase and instantly get a
downloadable and editable PDF for convenient study and review.
ATOMIC STRUCTURE, ISOTOPES, AND PERIODIC TRENDS
Question 1
A monatomic ion contains 17 protons, 18 electrons, and 20 neutrons. Which
designation correctly identifies the species?
−
A. 37 Cl
−
B. 35 Cl
,C. 37 Ar−
+
D. 38 Cl
🔴 Correct Answer: A. 37 Cl−
🔵 Explanation: The atomic number is 17, identifying chlorine. The mass number is 17
+ 20 = 37, and one more electron than protons gives a −1 charge.
Question 2
An element has two naturally occurring isotopes. Isotope A has a mass of 34.969 u
and an abundance of 75.77%, while isotope B has a mass of 36.966 u and an
abundance of 24.23%. What is the approximate average atomic mass?
A. 34.97 u
B. 35.45 u
C. 36.02 u
D. 36.97 u
🔴 Correct Answer: B. 35.45 u
🔵 Explanation: The weighted average is (34.969)(0.7577) + (36.966)(0.2423) ≈
35.45 u.
Question 3
Which change requires the greatest energy under comparable gaseous conditions?
A. Removing the first electron from Na
B. Removing the second electron from Na⁺
C. Removing the first electron from Mg
D. Removing the first electron from Al
🔴 Correct Answer: B. Removing the second electron from Na⁺
🔵 Explanation: After sodium loses one electron, Na⁺ has a noble-gas configuration.
Removing another electron disrupts a stable core and therefore requires dramatically
greater ionization energy.
Question 4
Which species is expected to have the smallest radius?
A. O²⁻
B. F⁻
C. Na⁺
D. Mg²⁺
,🔴 Correct Answer: D. Mg²⁺
🔵 Explanation: These ions are isoelectronic with 10 electrons. Increasing nuclear
charge pulls the same electron population closer to the nucleus, making Mg²⁺ smallest.
Question 5
Which statement best explains why atomic radius generally decreases from left to
right across a period?
A. The number of occupied energy levels decreases.
B. Effective nuclear charge increases while electrons are added to the same principal
shell.
C. Nuclear charge decreases as atomic number increases.
D. Electron shielding increases enough to overcome increasing nuclear charge.
🔴 Correct Answer: B. Effective nuclear charge increases while electrons are added
to the same principal shell.
🔵 Explanation: Electrons are added to the same general energy level while proton
number increases, producing stronger attraction between the nucleus and valence
electrons.
Question 6
An electron in a hydrogen atom transitions from n = 5 to n = 2. Which statement is
correct?
A. The atom absorbs energy.
B. The atom emits a photon.
C. The electron becomes unbound.
D. The photon has lower energy than a transition from n = 3 to n = 2.
🔴 Correct Answer: B. The atom emits a photon.
🔵 Explanation: A transition to a lower energy level releases energy as a photon.
The 5 → 2 transition is in the hydrogen Balmer series.
Question 7
Which set of quantum numbers is impossible for an electron?
A. n = 3, ℓ = 2, mℓ = 1, ms = + 12
B. n = 2, ℓ = 1, mℓ = 0, ms = − 12
1
C. n = 4, ℓ = 3, mℓ = −3, ms = + 2
1
D. n = 3, ℓ = 3, mℓ = 0, ms = − 2
, 🔴 Correct Answer: D. n = 3, ℓ = 3, mℓ = 0, ms = − 12
🔵 Explanation: For a given principal quantum number, ℓ ranges from 0 through n − 1.
For n = 3, ℓ can only be 0, 1, or 2.
Question 8
Which electron configuration represents the ground-state atom of chromium?
A. [Ar] 3d⁴4s²
B. [Ar] 3d⁵4s¹
C. [Ar] 3d⁶
D. [Ar] 3d³4s³
🔴 Correct Answer: B. [Ar] 3d⁵4s¹
🔵 Explanation: Chromium is an exception to the simplest filling prediction. A half-filled
3d subshell provides additional stability, giving [Ar] 3d⁵4s¹.
Question 9
Which element has the greatest first ionization energy?
A. Li
B. Be
C. B
D. C
🔴 Correct Answer: D. C
🔵 Explanation: Ionization energy generally increases across the period. Although B is
lower than Be because its removed electron is from a higher-energy 2p orbital, carbon
has the greatest value among these choices.
Question 10
Which element is most likely to form a stable 3− ion?
A. Mg
B. Al
C. P
D. Cl
🔴 Correct Answer: C. P
🔵 Explanation: Phosphorus has five valence electrons and can gain three electrons to
achieve a noble-gas configuration.
Question 11
COMPREHENSIVE EXAM PRACTICE & ACTUAL STUDY GUIDE — FULL TESTBANK:
150 ADVANCED PRACTICE QUESTIONS & 100% CORRECT ANSWERS WITH
RATIONALES — 2026/2027 LATEST UPDATE
TABLE OF CONTENTS
i. Atomic Structure, Isotopes, and Periodic Trends
ii. Chemical Bonding, Lewis Structures, and Molecular Geometry
iii. Stoichiometry, Chemical Reactions, and Limiting Reactants
iv. Gases, Liquids, Solids, and Intermolecular Forces
v. Thermochemistry and Energy Changes
vi. Quantum Theory, Electron Configuration, and Periodic Properties
vii. Solutions, Concentrations, and Colligative Properties
viii. Acids, Bases, pH, and Chemical Equilibrium
ix. Redox Chemistry and Electrochemical Principles
x. Advanced Integrated General Chemistry Applications
DESCRIPTION
This comprehensive Portage Learning CHEM 103 General Chemistry I practice
resource is designed to strengthen advanced understanding across the major
principles of introductory general chemistry. It emphasizes quantitative problem
solving, molecular interpretation, chemical reasoning, reaction analysis,
thermochemistry, atomic structure, bonding, gases, solutions, acids and bases, and
equilibrium. The questions are intentionally challenging and appropriate for students
seeking rigorous examination preparation, including college and advanced-level
chemistry learners. Students should expect 100+ questions and answers with a
rationale, realistic distractors, calculations, conceptual applications, and analytical
scenarios designed to expose common misconceptions. Purchase and instantly get a
downloadable and editable PDF for convenient study and review.
ATOMIC STRUCTURE, ISOTOPES, AND PERIODIC TRENDS
Question 1
A monatomic ion contains 17 protons, 18 electrons, and 20 neutrons. Which
designation correctly identifies the species?
−
A. 37 Cl
−
B. 35 Cl
,C. 37 Ar−
+
D. 38 Cl
🔴 Correct Answer: A. 37 Cl−
🔵 Explanation: The atomic number is 17, identifying chlorine. The mass number is 17
+ 20 = 37, and one more electron than protons gives a −1 charge.
Question 2
An element has two naturally occurring isotopes. Isotope A has a mass of 34.969 u
and an abundance of 75.77%, while isotope B has a mass of 36.966 u and an
abundance of 24.23%. What is the approximate average atomic mass?
A. 34.97 u
B. 35.45 u
C. 36.02 u
D. 36.97 u
🔴 Correct Answer: B. 35.45 u
🔵 Explanation: The weighted average is (34.969)(0.7577) + (36.966)(0.2423) ≈
35.45 u.
Question 3
Which change requires the greatest energy under comparable gaseous conditions?
A. Removing the first electron from Na
B. Removing the second electron from Na⁺
C. Removing the first electron from Mg
D. Removing the first electron from Al
🔴 Correct Answer: B. Removing the second electron from Na⁺
🔵 Explanation: After sodium loses one electron, Na⁺ has a noble-gas configuration.
Removing another electron disrupts a stable core and therefore requires dramatically
greater ionization energy.
Question 4
Which species is expected to have the smallest radius?
A. O²⁻
B. F⁻
C. Na⁺
D. Mg²⁺
,🔴 Correct Answer: D. Mg²⁺
🔵 Explanation: These ions are isoelectronic with 10 electrons. Increasing nuclear
charge pulls the same electron population closer to the nucleus, making Mg²⁺ smallest.
Question 5
Which statement best explains why atomic radius generally decreases from left to
right across a period?
A. The number of occupied energy levels decreases.
B. Effective nuclear charge increases while electrons are added to the same principal
shell.
C. Nuclear charge decreases as atomic number increases.
D. Electron shielding increases enough to overcome increasing nuclear charge.
🔴 Correct Answer: B. Effective nuclear charge increases while electrons are added
to the same principal shell.
🔵 Explanation: Electrons are added to the same general energy level while proton
number increases, producing stronger attraction between the nucleus and valence
electrons.
Question 6
An electron in a hydrogen atom transitions from n = 5 to n = 2. Which statement is
correct?
A. The atom absorbs energy.
B. The atom emits a photon.
C. The electron becomes unbound.
D. The photon has lower energy than a transition from n = 3 to n = 2.
🔴 Correct Answer: B. The atom emits a photon.
🔵 Explanation: A transition to a lower energy level releases energy as a photon.
The 5 → 2 transition is in the hydrogen Balmer series.
Question 7
Which set of quantum numbers is impossible for an electron?
A. n = 3, ℓ = 2, mℓ = 1, ms = + 12
B. n = 2, ℓ = 1, mℓ = 0, ms = − 12
1
C. n = 4, ℓ = 3, mℓ = −3, ms = + 2
1
D. n = 3, ℓ = 3, mℓ = 0, ms = − 2
, 🔴 Correct Answer: D. n = 3, ℓ = 3, mℓ = 0, ms = − 12
🔵 Explanation: For a given principal quantum number, ℓ ranges from 0 through n − 1.
For n = 3, ℓ can only be 0, 1, or 2.
Question 8
Which electron configuration represents the ground-state atom of chromium?
A. [Ar] 3d⁴4s²
B. [Ar] 3d⁵4s¹
C. [Ar] 3d⁶
D. [Ar] 3d³4s³
🔴 Correct Answer: B. [Ar] 3d⁵4s¹
🔵 Explanation: Chromium is an exception to the simplest filling prediction. A half-filled
3d subshell provides additional stability, giving [Ar] 3d⁵4s¹.
Question 9
Which element has the greatest first ionization energy?
A. Li
B. Be
C. B
D. C
🔴 Correct Answer: D. C
🔵 Explanation: Ionization energy generally increases across the period. Although B is
lower than Be because its removed electron is from a higher-energy 2p orbital, carbon
has the greatest value among these choices.
Question 10
Which element is most likely to form a stable 3− ion?
A. Mg
B. Al
C. P
D. Cl
🔴 Correct Answer: C. P
🔵 Explanation: Phosphorus has five valence electrons and can gain three electrons to
achieve a noble-gas configuration.
Question 11
