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CHEM 103 — Final Exam Edition
Questions with Correct Answers and
Rationales
Introduction
This document contains 180 CHEM 103 final exam practice questions
covering core general chemistry topics including equilibrium, acids
and bases, thermodynamics, atomic structure, bonding, solutions,
kinetics, stoichiometry, and molarity. Each multiple-choice question
includes the correct answer and a concise rationale explaining the
underlying concept or calculation.
Exam Questions and Answers
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Section 1
Questions 1–30
1. Which statement best describes the relationship between atomic
number and the identity of an element?
A. It equals the number of neutrons in the nucleus.
B. It equals the number of protons in the nucleus.
C. It equals the total number of nucleons.
D. It equals the number of valence electrons in every atom.
Correct Answer: B
Rationale: The atomic number is defined as the number of protons in
an atom's nucleus. Changing the number of protons changes the
element itself.
2. An isotope of carbon contains 6 protons and 8 neutrons. What is its
mass number?
A. 6
B. 8
C. 14
D. 48
Correct Answer: C
Rationale: Mass number is the sum of protons and neutrons: 6 + 8 =
14.
3. Which subatomic particle has approximately one atomic mass unit
and a negative charge?
A. Proton
B. Neutron
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C. Electron
D. Positron
Correct Answer: C
Rationale: An electron has a negative charge, but its mass is much
smaller than one atomic mass unit. The question's mass description is
therefore inconsistent; among the listed particles, the negatively
charged particle is the electron. In standard chemistry, a particle with
~1 amu and negative charge does not exist as a basic atomic
constituent.
4. Which trend generally increases from left to right across a period?
A. Atomic radius
B. Metallic character
C. Effective nuclear charge
D. Number of occupied energy levels
Correct Answer: C
Rationale: Across a period, proton number increases while shielding
changes relatively little, so effective nuclear charge generally
increases.
5. Which element is most likely to form a 2− ion?
A. Na
B. Mg
C. O
D. Al
Correct Answer: C
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Rationale: Oxygen is in Group 16 and commonly gains two electrons to
achieve a noble-gas-like valence configuration, forming O²−.
6. What is the name of Na2SO4?
A. Sodium sulfite
B. Sodium sulfate
C. Sodium sulfide
D. Sodium sulfur oxide
Correct Answer: B
Rationale: SO4²− is the sulfate ion, and Na+ is sodium. Therefore
Na2SO4 is sodium sulfate.
7. What is the correct formula for calcium nitrate?
A. CaNO3
B. Ca(NO3)2
C. Ca2NO3
D. Ca2(NO3)3
Correct Answer: B
Rationale: Calcium is Ca²+ and nitrate is NO3−. Two nitrate ions are
required to balance one Ca²+ ion, giving Ca(NO3)2.
8. Which bond is most directly associated with sharing electrons
between atoms?
A. Ionic
B. Covalent
C. Metallic
D. Hydrogen
Correct Answer: B
CHEM 103 — Final Exam Edition
Questions with Correct Answers and
Rationales
Introduction
This document contains 180 CHEM 103 final exam practice questions
covering core general chemistry topics including equilibrium, acids
and bases, thermodynamics, atomic structure, bonding, solutions,
kinetics, stoichiometry, and molarity. Each multiple-choice question
includes the correct answer and a concise rationale explaining the
underlying concept or calculation.
Exam Questions and Answers
,Page 2 of 79
Section 1
Questions 1–30
1. Which statement best describes the relationship between atomic
number and the identity of an element?
A. It equals the number of neutrons in the nucleus.
B. It equals the number of protons in the nucleus.
C. It equals the total number of nucleons.
D. It equals the number of valence electrons in every atom.
Correct Answer: B
Rationale: The atomic number is defined as the number of protons in
an atom's nucleus. Changing the number of protons changes the
element itself.
2. An isotope of carbon contains 6 protons and 8 neutrons. What is its
mass number?
A. 6
B. 8
C. 14
D. 48
Correct Answer: C
Rationale: Mass number is the sum of protons and neutrons: 6 + 8 =
14.
3. Which subatomic particle has approximately one atomic mass unit
and a negative charge?
A. Proton
B. Neutron
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C. Electron
D. Positron
Correct Answer: C
Rationale: An electron has a negative charge, but its mass is much
smaller than one atomic mass unit. The question's mass description is
therefore inconsistent; among the listed particles, the negatively
charged particle is the electron. In standard chemistry, a particle with
~1 amu and negative charge does not exist as a basic atomic
constituent.
4. Which trend generally increases from left to right across a period?
A. Atomic radius
B. Metallic character
C. Effective nuclear charge
D. Number of occupied energy levels
Correct Answer: C
Rationale: Across a period, proton number increases while shielding
changes relatively little, so effective nuclear charge generally
increases.
5. Which element is most likely to form a 2− ion?
A. Na
B. Mg
C. O
D. Al
Correct Answer: C
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Rationale: Oxygen is in Group 16 and commonly gains two electrons to
achieve a noble-gas-like valence configuration, forming O²−.
6. What is the name of Na2SO4?
A. Sodium sulfite
B. Sodium sulfate
C. Sodium sulfide
D. Sodium sulfur oxide
Correct Answer: B
Rationale: SO4²− is the sulfate ion, and Na+ is sodium. Therefore
Na2SO4 is sodium sulfate.
7. What is the correct formula for calcium nitrate?
A. CaNO3
B. Ca(NO3)2
C. Ca2NO3
D. Ca2(NO3)3
Correct Answer: B
Rationale: Calcium is Ca²+ and nitrate is NO3−. Two nitrate ions are
required to balance one Ca²+ ion, giving Ca(NO3)2.
8. Which bond is most directly associated with sharing electrons
between atoms?
A. Ionic
B. Covalent
C. Metallic
D. Hydrogen
Correct Answer: B
