1 MAXE · 401 MEHC
★
University of Wisconsin–Madison
College of Letters & Science — Department of Chemistry
NUMEN LUMEN
EST. 1848
NUMEN LUMEN · GOD, OUR LIGHT
CHEM 104 Exam 1 — General Chemistry II
P E R I O D I C TA B L E · ATO M I C ST R U CT U R E · B O N D I N G · C H E M I C A L Q UA N T I T I E S
INSTITUTION University of Wisconsin–Madison COURSE CODE CHEM 104
PROGRAM Bachelor of Science — General ACADEMIC YEAR
Chemistry Sequence
EXAM TITLE CHEM 104 Exam 1 — General TOTAL QUESTIONS 159 Questions
Chemistry II
COURSE TITLE General Chemistry II FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Element symbols, polyatomic ions, periodic trends, and nomenclature are core testable content.
▸ Significant figures, scientific notation, and unit conversions are emphasized.
▸ Correct answers and rationales appear below each question for self-assessment and review.
▸ A periodic table reference and ion chart are recommended as supplementary resources.
, SECTION I — ELEMENTS, IONS, PERIODIC TABLE &
Questions 1 – 159
CHEMICAL PRINCIPLES
1. A chemistry student is asked to interpret a molecular formula and determine what the
subscripts represent. In chemical formulas, what do the subscripts indicate?
A. The charge of each atom in the molecule
B. The number of atoms of each element in the molecule
C. The mass number of each element
D. The ionization energy of the atoms
CORRECT ANSWER B — The number of atoms of each element in the molecule
RATIONALE In chemical formulas, subscripts indicate the number of atoms of each element
present in one molecule. For example, in H₂O₂, the subscript "2" after H and O
indicates two hydrogen atoms and two oxygen atoms, for a total of 4 atoms in the
molecule. This is a fundamental concept in stoichiometry and molecular
interpretation.
2. A student is predicting the charge of an anion formed by a nonmetal. The element sulfur
(S) is in group 6A. What charge will the sulfide ion carry, and what is the rule for
determining it?
A. +2; group number equals the charge for nonmetals
B. −2; group number minus 8 equals the charge for nonmetal anions
C. +6; group number equals the charge
D. −6; group number minus 2 equals the charge
CORRECT ANSWER B — −2; group number minus 8 equals the charge for nonmetal anions
RATIONALE For nonmetal anions, the charge is determined by the formula: group number − 8
= charge. Sulfur is in group 6A, so 6 − 8 = −2, giving the sulfide ion S²⁻. This reflects
how many electrons the nonmetal gains to achieve an octet (8 valence electrons).
Metals form cations with a positive charge equal to their group number;
nonmetals form anions using this subtraction rule.
,3. A semiconductor manufacturer uses an element that is the second most abundant
element in Earth's crust and is essential for computer chips and solar panels. Which
element, with the symbol Si, is this?
A. Silver
B. Silicon
C. Sulfur
D. Selenium
CORRECT ANSWER B — Silicon
RATIONALE Si is the chemical symbol for silicon, a metalloid in group 4A (group 14). Silicon is
the second most abundant element in Earth's crust (after oxygen) and is the
foundational material for the semiconductor industry, used extensively in
computer chips, solar panels, and electronic devices. Silver (Ag) and sulfur (S) are
different elements; selenium (Se) is a nonmetal in group 6A.
4. A laboratory technician needs to calculate the density of an unknown liquid. She
measures a mass of 24.0 g and a volume of 30.0 mL. Which formula should she use, and
what is the density?
A. Density = volume / mass; 1.25 g/mL
B. Density = mass / volume; 0.800 g/mL
C. Density = mass × volume; 720 g·mL
D. Density = mass + volume; 54.0 g/mL
CORRECT ANSWER B — Density = mass / volume; 0.800 g/mL
RATIONALE Density is defined as mass divided by volume: D = m/V. Using the measured
values, 24.0 g ÷ 30.0 mL = 0.800 g/mL. This is a fundamental physical property
used to identify substances and is temperature-dependent. The formula must be
memorized precisely — inverting mass and volume (A) produces a different,
incorrect value.
, 5. Carbon-12 and carbon-14 are both carbon atoms but have different mass numbers. Which
statement correctly describes the relationship between these two atoms?
A. They have the same number of protons and neutrons
B. They are isotopes: same number of protons, different number of neutrons
C. They are different elements with different atomic numbers
D. They have different numbers of protons but the same number of neutrons
CORRECT ANSWER B — They are isotopes: same number of protons, different number of
neutrons
RATIONALE Isotopes are atoms of the same element (same atomic number/same number of
protons) that differ in the number of neutrons, resulting in different mass
numbers. Carbon-12 has 6 protons and 6 neutrons; carbon-14 has 6 protons and 8
neutrons. They are both carbon (same element) because the proton count is
identical. The heavier isotope has more neutrons.
6. A student is memorizing element symbols and encounters "Fe." Which element does this
symbol represent, and what is its atomic number?
A. Fluorine, atomic number 9
B. Iron, atomic number 26
C. Fermium, atomic number 100
D. Francium, atomic number 87
CORRECT ANSWER B — Iron, atomic number 26
RATIONALE Fe is the chemical symbol for iron, derived from the Latin word "ferrum." Iron is a
transition metal in period 4, group 8, with atomic number 26. It is one of the most
abundant elements on Earth and is essential for hemoglobin function in
biological systems. The symbol Fe must be memorized as it does not intuitively
match the English name.
★
University of Wisconsin–Madison
College of Letters & Science — Department of Chemistry
NUMEN LUMEN
EST. 1848
NUMEN LUMEN · GOD, OUR LIGHT
CHEM 104 Exam 1 — General Chemistry II
P E R I O D I C TA B L E · ATO M I C ST R U CT U R E · B O N D I N G · C H E M I C A L Q UA N T I T I E S
INSTITUTION University of Wisconsin–Madison COURSE CODE CHEM 104
PROGRAM Bachelor of Science — General ACADEMIC YEAR
Chemistry Sequence
EXAM TITLE CHEM 104 Exam 1 — General TOTAL QUESTIONS 159 Questions
Chemistry II
COURSE TITLE General Chemistry II FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question.
▸ Element symbols, polyatomic ions, periodic trends, and nomenclature are core testable content.
▸ Significant figures, scientific notation, and unit conversions are emphasized.
▸ Correct answers and rationales appear below each question for self-assessment and review.
▸ A periodic table reference and ion chart are recommended as supplementary resources.
, SECTION I — ELEMENTS, IONS, PERIODIC TABLE &
Questions 1 – 159
CHEMICAL PRINCIPLES
1. A chemistry student is asked to interpret a molecular formula and determine what the
subscripts represent. In chemical formulas, what do the subscripts indicate?
A. The charge of each atom in the molecule
B. The number of atoms of each element in the molecule
C. The mass number of each element
D. The ionization energy of the atoms
CORRECT ANSWER B — The number of atoms of each element in the molecule
RATIONALE In chemical formulas, subscripts indicate the number of atoms of each element
present in one molecule. For example, in H₂O₂, the subscript "2" after H and O
indicates two hydrogen atoms and two oxygen atoms, for a total of 4 atoms in the
molecule. This is a fundamental concept in stoichiometry and molecular
interpretation.
2. A student is predicting the charge of an anion formed by a nonmetal. The element sulfur
(S) is in group 6A. What charge will the sulfide ion carry, and what is the rule for
determining it?
A. +2; group number equals the charge for nonmetals
B. −2; group number minus 8 equals the charge for nonmetal anions
C. +6; group number equals the charge
D. −6; group number minus 2 equals the charge
CORRECT ANSWER B — −2; group number minus 8 equals the charge for nonmetal anions
RATIONALE For nonmetal anions, the charge is determined by the formula: group number − 8
= charge. Sulfur is in group 6A, so 6 − 8 = −2, giving the sulfide ion S²⁻. This reflects
how many electrons the nonmetal gains to achieve an octet (8 valence electrons).
Metals form cations with a positive charge equal to their group number;
nonmetals form anions using this subtraction rule.
,3. A semiconductor manufacturer uses an element that is the second most abundant
element in Earth's crust and is essential for computer chips and solar panels. Which
element, with the symbol Si, is this?
A. Silver
B. Silicon
C. Sulfur
D. Selenium
CORRECT ANSWER B — Silicon
RATIONALE Si is the chemical symbol for silicon, a metalloid in group 4A (group 14). Silicon is
the second most abundant element in Earth's crust (after oxygen) and is the
foundational material for the semiconductor industry, used extensively in
computer chips, solar panels, and electronic devices. Silver (Ag) and sulfur (S) are
different elements; selenium (Se) is a nonmetal in group 6A.
4. A laboratory technician needs to calculate the density of an unknown liquid. She
measures a mass of 24.0 g and a volume of 30.0 mL. Which formula should she use, and
what is the density?
A. Density = volume / mass; 1.25 g/mL
B. Density = mass / volume; 0.800 g/mL
C. Density = mass × volume; 720 g·mL
D. Density = mass + volume; 54.0 g/mL
CORRECT ANSWER B — Density = mass / volume; 0.800 g/mL
RATIONALE Density is defined as mass divided by volume: D = m/V. Using the measured
values, 24.0 g ÷ 30.0 mL = 0.800 g/mL. This is a fundamental physical property
used to identify substances and is temperature-dependent. The formula must be
memorized precisely — inverting mass and volume (A) produces a different,
incorrect value.
, 5. Carbon-12 and carbon-14 are both carbon atoms but have different mass numbers. Which
statement correctly describes the relationship between these two atoms?
A. They have the same number of protons and neutrons
B. They are isotopes: same number of protons, different number of neutrons
C. They are different elements with different atomic numbers
D. They have different numbers of protons but the same number of neutrons
CORRECT ANSWER B — They are isotopes: same number of protons, different number of
neutrons
RATIONALE Isotopes are atoms of the same element (same atomic number/same number of
protons) that differ in the number of neutrons, resulting in different mass
numbers. Carbon-12 has 6 protons and 6 neutrons; carbon-14 has 6 protons and 8
neutrons. They are both carbon (same element) because the proton count is
identical. The heavier isotope has more neutrons.
6. A student is memorizing element symbols and encounters "Fe." Which element does this
symbol represent, and what is its atomic number?
A. Fluorine, atomic number 9
B. Iron, atomic number 26
C. Fermium, atomic number 100
D. Francium, atomic number 87
CORRECT ANSWER B — Iron, atomic number 26
RATIONALE Fe is the chemical symbol for iron, derived from the Latin word "ferrum." Iron is a
transition metal in period 4, group 8, with atomic number 26. It is one of the most
abundant elements on Earth and is essential for hemoglobin function in
biological systems. The symbol Fe must be memorized as it does not intuitively
match the English name.
