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In-Depth CHEM 103 Final Review and
Problem-Solving Workbook 2025
True or False
The fifth subshell contains four subshells.
Correct answer: True
Rationale: The fifth energy level (n=5) contains the s, p, d, and f subshells—four in total. The
statement is true.
T or F
Fe2+ and Fe3+ are isoelectronic.
Correct answer: False
Rationale: Fe2+ has 24 electrons, while Fe3+ has 23 electrons—different configurations.
Isoelectronic species must have the same number of electrons.
T or F
K+ and Cl− have the same electronic configuration as argon.
Correct answer: True
Rationale: Both ions have 18 electrons, giving them the same configuration as argon
(1s²2s²2p⁶3s²3p⁶).
T or F
Compounds containing hydrogen attached to an oxygen or nitrogen atom can exhibit hydrogen
bonding.
Correct answer: True
Rationale: Hydrogen bonds form between hydrogen and highly electronegative atoms like O, N,
or F, leading to strong intermolecular attractions.
T or F
Metal atoms gain electrons to become cations in ionic compounds.
Correct answer: False
Rationale: Metals lose electrons to form positively charged cations, not gain them.
T or F
The reaction Ca + Cl₂ → CaCl₂ is a redox reaction.
Correct answer: True
Rationale: Calcium is oxidized (loses electrons), and chlorine is reduced (gains electrons),
making it a redox reaction.
T or F
CO₂ is a nonpolar molecule.
Correct answer: True
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Rationale: Although C–O bonds are polar, the linear symmetry of CO₂ causes dipoles to cancel
out, making the molecule nonpolar.
T or F
The reaction 3Be + P₂ → Be₃P₂ is correctly balanced as written.
Correct answer: True
Rationale: Each element’s atoms are balanced: 3 Be and 2 P on both sides.
T or F
Carbon tetrachloride (CCl₄) is a trigonal planar molecule.
Correct answer: False
Rationale: CCl₄ has four bonding pairs around carbon, forming a tetrahedral shape, not trigonal
planar.
T or F
In an exothermic reaction, heat is absorbed from the surroundings.
Correct answer: False
Rationale: Exothermic reactions release heat; endothermic reactions absorb it.
T or F
Products are always written on the left side of a chemical equation.
Correct answer: False
Rationale: Reactants are written on the left and products on the right.
T or F
The reaction CaO + CO₂ → CaCO₃ is a non-redox combination reaction.
Correct answer: True
Rationale: There is no change in oxidation states; it’s a combination reaction but not a redox
one.
T or F
In the reaction Cl₂ + FeBr₂ → FeCl₂ + Br₂, the Cl atoms are oxidized.
Correct answer: False
Rationale: Cl₂ is reduced (gains electrons to form Cl⁻), while Br⁻ is oxidized to Br₂.
Which of the following electronic changes will cause a group 7A element to achieve a noble gas
configuration?
A. Lose one electron
B. Gain one electron
C. Gain two electrons
D. Share one electron
Correct answer: B. Gain one electron
Rationale: Group 7A (halogens) need one more electron to achieve a stable octet like noble
gases.
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Which of the following pairs does not have the same number of electrons in the outermost
orbital?
A. Na and K
B. K and Ca
C. Li and Na
D. O and S
Correct answer: B. K and Ca
Rationale: K has one valence electron (group 1A), while Ca has two (group 2A).
The correct name for N₂O₄ is
A. Nitrogen oxide
B. Dinitrogen tetraoxide
C. Nitrogen tetroxide
D. Dinitrogen tetroxide
Correct answer: D. Dinitrogen tetroxide
Rationale: Covalent compounds use prefixes to denote atom counts—“di-” for 2 N and “tetra-”
for 4 O.
Which compound is polar?
A. CH₄
B. CF₄
C. CO₂
D. CF₃Cl
Correct answer: D. CF₃Cl
Rationale: CF₃Cl has unequal charge distribution due to the presence of Cl, creating a dipole.
The others are symmetrical and nonpolar.
Which compound would be classified as ionic?
A. CO₂
B. CH₄
C. KBr
D. H₂O
Correct answer: C. KBr
Rationale: K is a metal and Br a nonmetal, forming ionic bonds through electron transfer.
Which of the following is a double replacement reaction?
A. H₂ + Cl₂ → 2HCl
B. NaCl + AgNO₃ → NaNO₃ + AgCl
C. Zn + HCl → ZnCl₂ + H₂
D. CH₄ + O₂ → CO₂ + H₂O
Correct answer: B. NaCl + AgNO₃ → NaNO₃ + AgCl
Rationale: Ions exchange partners between compounds—typical of double replacement
reactions.
Which element is most likely a metalloid?
A. Ge
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B. S
C. K
D. Ne
Correct answer: A. Ge
Rationale: Germanium has properties of both metals and nonmetals, placing it among
metalloids.
Which element has the largest atomic radius?
A. Na
B. Cl
C. Au
D. N
Correct answer: C. Au
Rationale: Atomic radius increases down a group; gold is much lower in the periodic table than
the others.
Which would be the most polar molecule?
A. CO₂
B. H₂S
C. CH₄
D. N₂
Correct answer: B. H₂S
Rationale: H–S bonds have an electronegativity difference and a bent shape, creating a polar
molecule.
The shape of BF₃ is
A. Linear
B. Tetrahedral
C. Trigonal planar
D. Bent
Correct answer: C. Trigonal planar
Rationale: Boron forms three bonds and no lone pairs, resulting in a trigonal planar structure.
Which of the following statements conforms to periodic trends?
A. Ionization energy decreases across a period
B. Elements become more likely to be gases at the bottom of a group
C. Atomic size decreases down a group
D. Elements become more likely to be solids at the bottom of a group
Correct answer: D. Elements become more likely to be solids at the bottom of a group
Rationale: Metallic character and atomic mass increase down a group, favoring solid states.
Which of the following equations represents Boyle’s Law?
A) V ∝ T
B) P₁V₁ = P₂V₂
C) PV/T = constant
D) V ∝ n
In-Depth CHEM 103 Final Review and
Problem-Solving Workbook 2025
True or False
The fifth subshell contains four subshells.
Correct answer: True
Rationale: The fifth energy level (n=5) contains the s, p, d, and f subshells—four in total. The
statement is true.
T or F
Fe2+ and Fe3+ are isoelectronic.
Correct answer: False
Rationale: Fe2+ has 24 electrons, while Fe3+ has 23 electrons—different configurations.
Isoelectronic species must have the same number of electrons.
T or F
K+ and Cl− have the same electronic configuration as argon.
Correct answer: True
Rationale: Both ions have 18 electrons, giving them the same configuration as argon
(1s²2s²2p⁶3s²3p⁶).
T or F
Compounds containing hydrogen attached to an oxygen or nitrogen atom can exhibit hydrogen
bonding.
Correct answer: True
Rationale: Hydrogen bonds form between hydrogen and highly electronegative atoms like O, N,
or F, leading to strong intermolecular attractions.
T or F
Metal atoms gain electrons to become cations in ionic compounds.
Correct answer: False
Rationale: Metals lose electrons to form positively charged cations, not gain them.
T or F
The reaction Ca + Cl₂ → CaCl₂ is a redox reaction.
Correct answer: True
Rationale: Calcium is oxidized (loses electrons), and chlorine is reduced (gains electrons),
making it a redox reaction.
T or F
CO₂ is a nonpolar molecule.
Correct answer: True
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Rationale: Although C–O bonds are polar, the linear symmetry of CO₂ causes dipoles to cancel
out, making the molecule nonpolar.
T or F
The reaction 3Be + P₂ → Be₃P₂ is correctly balanced as written.
Correct answer: True
Rationale: Each element’s atoms are balanced: 3 Be and 2 P on both sides.
T or F
Carbon tetrachloride (CCl₄) is a trigonal planar molecule.
Correct answer: False
Rationale: CCl₄ has four bonding pairs around carbon, forming a tetrahedral shape, not trigonal
planar.
T or F
In an exothermic reaction, heat is absorbed from the surroundings.
Correct answer: False
Rationale: Exothermic reactions release heat; endothermic reactions absorb it.
T or F
Products are always written on the left side of a chemical equation.
Correct answer: False
Rationale: Reactants are written on the left and products on the right.
T or F
The reaction CaO + CO₂ → CaCO₃ is a non-redox combination reaction.
Correct answer: True
Rationale: There is no change in oxidation states; it’s a combination reaction but not a redox
one.
T or F
In the reaction Cl₂ + FeBr₂ → FeCl₂ + Br₂, the Cl atoms are oxidized.
Correct answer: False
Rationale: Cl₂ is reduced (gains electrons to form Cl⁻), while Br⁻ is oxidized to Br₂.
Which of the following electronic changes will cause a group 7A element to achieve a noble gas
configuration?
A. Lose one electron
B. Gain one electron
C. Gain two electrons
D. Share one electron
Correct answer: B. Gain one electron
Rationale: Group 7A (halogens) need one more electron to achieve a stable octet like noble
gases.
,100%
Which of the following pairs does not have the same number of electrons in the outermost
orbital?
A. Na and K
B. K and Ca
C. Li and Na
D. O and S
Correct answer: B. K and Ca
Rationale: K has one valence electron (group 1A), while Ca has two (group 2A).
The correct name for N₂O₄ is
A. Nitrogen oxide
B. Dinitrogen tetraoxide
C. Nitrogen tetroxide
D. Dinitrogen tetroxide
Correct answer: D. Dinitrogen tetroxide
Rationale: Covalent compounds use prefixes to denote atom counts—“di-” for 2 N and “tetra-”
for 4 O.
Which compound is polar?
A. CH₄
B. CF₄
C. CO₂
D. CF₃Cl
Correct answer: D. CF₃Cl
Rationale: CF₃Cl has unequal charge distribution due to the presence of Cl, creating a dipole.
The others are symmetrical and nonpolar.
Which compound would be classified as ionic?
A. CO₂
B. CH₄
C. KBr
D. H₂O
Correct answer: C. KBr
Rationale: K is a metal and Br a nonmetal, forming ionic bonds through electron transfer.
Which of the following is a double replacement reaction?
A. H₂ + Cl₂ → 2HCl
B. NaCl + AgNO₃ → NaNO₃ + AgCl
C. Zn + HCl → ZnCl₂ + H₂
D. CH₄ + O₂ → CO₂ + H₂O
Correct answer: B. NaCl + AgNO₃ → NaNO₃ + AgCl
Rationale: Ions exchange partners between compounds—typical of double replacement
reactions.
Which element is most likely a metalloid?
A. Ge
, 100%
B. S
C. K
D. Ne
Correct answer: A. Ge
Rationale: Germanium has properties of both metals and nonmetals, placing it among
metalloids.
Which element has the largest atomic radius?
A. Na
B. Cl
C. Au
D. N
Correct answer: C. Au
Rationale: Atomic radius increases down a group; gold is much lower in the periodic table than
the others.
Which would be the most polar molecule?
A. CO₂
B. H₂S
C. CH₄
D. N₂
Correct answer: B. H₂S
Rationale: H–S bonds have an electronegativity difference and a bent shape, creating a polar
molecule.
The shape of BF₃ is
A. Linear
B. Tetrahedral
C. Trigonal planar
D. Bent
Correct answer: C. Trigonal planar
Rationale: Boron forms three bonds and no lone pairs, resulting in a trigonal planar structure.
Which of the following statements conforms to periodic trends?
A. Ionization energy decreases across a period
B. Elements become more likely to be gases at the bottom of a group
C. Atomic size decreases down a group
D. Elements become more likely to be solids at the bottom of a group
Correct answer: D. Elements become more likely to be solids at the bottom of a group
Rationale: Metallic character and atomic mass increase down a group, favoring solid states.
Which of the following equations represents Boyle’s Law?
A) V ∝ T
B) P₁V₁ = P₂V₂
C) PV/T = constant
D) V ∝ n
