UNIVERSITY OF FLORIDA CHM2045 GENERAL CHEMISTRY 1 – EXAM-STYLE
QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS | PLUS
RATIONALES | GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP |
STUDY GUIDE | PRACTICE TEST
Section One: Questions 1 – 50
1. Which of the following represents a chemical change rather than a physical
change?
A. Sublimation of dry ice into gaseous carbon dioxide
B. Dissolving sodium chloride in distilled water
C. The formation of a precipitate upon mixing two clear solutions
D. The separation of a mixture by fractional distillation
Correct Answer: C. The formation of a precipitate upon mixing two clear
solutions
Rationale: A chemical change results in the formation of a new substance with a
different chemical composition. The formation of a precipitate from two clear
solutions indicates a chemical reaction producing an insoluble compound.
Sublimation (A), dissolving salt (B), and distillation (D) are all physical changes
because they involve changes in state or separation of components without altering
the chemical identity of the matter.
<br> <br>
2. Which of the following properties is an example of an intensive property?
A. Mass
B. Volume
,C. Density
D. Energy
Correct Answer: C. Density
Rationale: Intensive properties are independent of the amount of substance
present; density is a characteristic ratio of mass to volume that remains constant
regardless of sample size. Mass (A), volume (B), and energy (D) are extensive
properties because their values depend directly on the amount of material present.
<br> <br>
3. The electron configuration for a neutral chlorine atom in its ground state is:
A. 1s²2s²2p⁶3s²3p⁵
B. 1s²2s²2p⁶3s²3p⁴
C. 1s²2s²2p⁶3s²3p⁶4s¹
D. 1s²2s²2p⁶3s²3d⁵
Correct Answer: A. 1s²2s²2p⁶3s²3p⁵
Rationale: A neutral chlorine atom has an atomic number of 17, meaning it
possesses 17 electrons. The electrons fill orbitals in order of increasing energy: 1s,
2s, 2p, 3s, and then 3p. The 3p subshell can hold a maximum of six electrons, and
chlorine has five electrons in this subshell, giving the configuration 1s²2s²2p⁶3s²3p⁵.
Option B represents sulfur (16 e⁻), C represents potassium (19 e⁻), and D is an
impossible ground-state configuration for chlorine.
<br> <br>
4. According to the periodic trend, which of the following atoms has the largest
atomic radius?
,A. Oxygen
B. Fluorine
C. Nitrogen
D. Boron
Correct Answer: D. Boron
Rationale: Atomic radius generally decreases across a period from left to right
because increasing nuclear charge pulls the electron cloud closer to the nucleus.
These elements are in the second period; boron is furthest to the left, thus has the
least effective nuclear charge and the largest atomic radius among them. Fluorine
(B) is furthest to the right and is the smallest of the options.
<br> <br>
5. Which of the following molecules is nonpolar?
A. Water (H₂O)
B. Ammonia (NH₃)
C. Carbon tetrachloride (CCl₄)
D. Sulfur dioxide (SO₂)
Correct Answer: C. Carbon tetrachloride (CCl₄)
Rationale: Carbon tetrachloride has a tetrahedral molecular geometry with four
identical C-Cl bonds. The individual bond dipoles are symmetrically arranged and
cancel each other out, resulting in a net dipole moment of zero and a nonpolar
molecule. Water (A), ammonia (B), and sulfur dioxide (D) are all polar due to their
asymmetrical geometries and non-canceling dipole moments.
<br> <br>
, 6. What is the mass of 2.50 moles of CO₂?
A. 44.0 g
B. 110. g
C. 88.0 g
D. 1.10 × 10² g
Correct Answer: B. 110. g
Rationale: The molar mass of CO₂ is 44.01 g/mol (12.01 g/mol for C + 2 × 16.00
g/mol for O). To find the mass, multiply the number of moles by the molar mass:
2.50 mol × 44.01 g/mol = 110.025 g, which is correctly rounded to three significant
figures as 110. g. Option A is the mass of 1 mole, C is the mass for 2 moles, and D
misinterprets the mathematical operation.
<br> <br>
7. A solution with a pH of 3.0 has a hydronium ion concentration that is _____ a
solution with a pH of 5.0.
A. One hundred times less than
B. Twice as high as
C. One hundred times greater than
D. Twenty times greater than
Correct Answer: C. One hundred times greater than
Rationale: The pH scale is logarithmic; a change of 1 pH unit corresponds to a
tenfold change in [H₃O⁺]. A difference of 2 pH units (from 5.0 to 3.0) means the
[H₃O⁺] is 10² or 100 times greater. This is calculated as [H₃O⁺] = 10⁻³ M versus 10⁻⁵
M.
<br> <br>
QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED ANSWERS | PLUS
RATIONALES | GUARANTEED PASS | 2026/27 LATEST UPDATE | EXAM PREP |
STUDY GUIDE | PRACTICE TEST
Section One: Questions 1 – 50
1. Which of the following represents a chemical change rather than a physical
change?
A. Sublimation of dry ice into gaseous carbon dioxide
B. Dissolving sodium chloride in distilled water
C. The formation of a precipitate upon mixing two clear solutions
D. The separation of a mixture by fractional distillation
Correct Answer: C. The formation of a precipitate upon mixing two clear
solutions
Rationale: A chemical change results in the formation of a new substance with a
different chemical composition. The formation of a precipitate from two clear
solutions indicates a chemical reaction producing an insoluble compound.
Sublimation (A), dissolving salt (B), and distillation (D) are all physical changes
because they involve changes in state or separation of components without altering
the chemical identity of the matter.
<br> <br>
2. Which of the following properties is an example of an intensive property?
A. Mass
B. Volume
,C. Density
D. Energy
Correct Answer: C. Density
Rationale: Intensive properties are independent of the amount of substance
present; density is a characteristic ratio of mass to volume that remains constant
regardless of sample size. Mass (A), volume (B), and energy (D) are extensive
properties because their values depend directly on the amount of material present.
<br> <br>
3. The electron configuration for a neutral chlorine atom in its ground state is:
A. 1s²2s²2p⁶3s²3p⁵
B. 1s²2s²2p⁶3s²3p⁴
C. 1s²2s²2p⁶3s²3p⁶4s¹
D. 1s²2s²2p⁶3s²3d⁵
Correct Answer: A. 1s²2s²2p⁶3s²3p⁵
Rationale: A neutral chlorine atom has an atomic number of 17, meaning it
possesses 17 electrons. The electrons fill orbitals in order of increasing energy: 1s,
2s, 2p, 3s, and then 3p. The 3p subshell can hold a maximum of six electrons, and
chlorine has five electrons in this subshell, giving the configuration 1s²2s²2p⁶3s²3p⁵.
Option B represents sulfur (16 e⁻), C represents potassium (19 e⁻), and D is an
impossible ground-state configuration for chlorine.
<br> <br>
4. According to the periodic trend, which of the following atoms has the largest
atomic radius?
,A. Oxygen
B. Fluorine
C. Nitrogen
D. Boron
Correct Answer: D. Boron
Rationale: Atomic radius generally decreases across a period from left to right
because increasing nuclear charge pulls the electron cloud closer to the nucleus.
These elements are in the second period; boron is furthest to the left, thus has the
least effective nuclear charge and the largest atomic radius among them. Fluorine
(B) is furthest to the right and is the smallest of the options.
<br> <br>
5. Which of the following molecules is nonpolar?
A. Water (H₂O)
B. Ammonia (NH₃)
C. Carbon tetrachloride (CCl₄)
D. Sulfur dioxide (SO₂)
Correct Answer: C. Carbon tetrachloride (CCl₄)
Rationale: Carbon tetrachloride has a tetrahedral molecular geometry with four
identical C-Cl bonds. The individual bond dipoles are symmetrically arranged and
cancel each other out, resulting in a net dipole moment of zero and a nonpolar
molecule. Water (A), ammonia (B), and sulfur dioxide (D) are all polar due to their
asymmetrical geometries and non-canceling dipole moments.
<br> <br>
, 6. What is the mass of 2.50 moles of CO₂?
A. 44.0 g
B. 110. g
C. 88.0 g
D. 1.10 × 10² g
Correct Answer: B. 110. g
Rationale: The molar mass of CO₂ is 44.01 g/mol (12.01 g/mol for C + 2 × 16.00
g/mol for O). To find the mass, multiply the number of moles by the molar mass:
2.50 mol × 44.01 g/mol = 110.025 g, which is correctly rounded to three significant
figures as 110. g. Option A is the mass of 1 mole, C is the mass for 2 moles, and D
misinterprets the mathematical operation.
<br> <br>
7. A solution with a pH of 3.0 has a hydronium ion concentration that is _____ a
solution with a pH of 5.0.
A. One hundred times less than
B. Twice as high as
C. One hundred times greater than
D. Twenty times greater than
Correct Answer: C. One hundred times greater than
Rationale: The pH scale is logarithmic; a change of 1 pH unit corresponds to a
tenfold change in [H₃O⁺]. A difference of 2 pH units (from 5.0 to 3.0) means the
[H₃O⁺] is 10² or 100 times greater. This is calculated as [H₃O⁺] = 10⁻³ M versus 10⁻⁵
M.
<br> <br>
