ORGANIC CHEMISTRY 5TH
EDITION, STUDENT STUDY
GUIDE AND SOLUTIONS –
(KLEIN & STARKEY, 2025) |
ALL 27 CHAPTERS
COVERED
Organic Chemistry 5th Edition (Klein & Starkey, 2025)
Comprehensive Practice Exam | Questions with Bolded
Correct Answers & Detailed Rationales
Based on the official chapter structure covering all 27 chapters
Chapter 1: Electrons, Bonds, and Molecular Properties
(Questions 1–10)
1. What is the formal charge on a carbon atom with three bonds and one lone
pair?
,A. +1
B. 0
C. −1
D. +2
Rationale: Formal charge = Valence electrons − (Lone pair electrons + ½ Bonding
electrons). Carbon has 4 valence electrons. FC = 4 − (2 + 3) = −1. A carbon with three
bonds and one lone pair has a negative formal charge (carbanion).
2. Which of the following molecules has a net dipole moment?
A. CO₂
B. CCl₄
C. CH₂Cl₂
D. BF₃
Rationale: CH₂Cl₂ has a net dipole moment because the C−Cl and C−H bond dipoles do
not cancel. CO₂, CCl₄, and BF₃ are symmetrical and have zero net dipole moments.
3. What is the hybridization of the oxygen atom in water (H₂O)?
A. sp
B. sp³
C. sp²
D. sp³d
Rationale: Oxygen in water has two bonding pairs and two lone pairs, giving it
tetrahedral electron geometry and sp³ hybridization.
4. Which of the following is the strongest type of intermolecular force?
A. London dispersion
B. Dipole-dipole
C. Hydrogen bonding
D. Ion-dipole
Rationale: Hydrogen bonding (when H is bonded to N, O, or F) is stronger than typical
dipole-dipole and London dispersion forces. Ion-dipole is stronger but occurs in
solutions.
5. What is the molecular geometry of a carbon atom with four single bonds?
,A. Trigonal planar
B. Linear
C. Tetrahedral
D. Bent
Rationale: Four bonding pairs around carbon give tetrahedral geometry with bond
angles of 109.5°.
6. Which atomic orbital is higher in energy?
A. 2s
B. 2p
C. They are equal
D. 1s
Rationale: Within the same principal quantum level, p orbitals are higher in energy than
s orbitals due to greater penetration and shielding effects.
7. How many valence electrons does nitrogen have?
A. 3
B. 4
C. 5
D. 7
Rationale: Nitrogen is in Group 15 and has 5 valence electrons (2s² 2p³).
8. Which of the following bonds is most polar?
A. C−H
B. C−C
C. O−H
D. C−O
Rationale: Electronegativity difference: O (3.5) − H (2.1) = 1.4. C−O is 1.0. C−H is 0.4.
C−C is 0. The O−H bond is most polar.
9. What is the bond angle in a molecule with sp hybridization?
A. 109.5°
B. 120°
C. 180°
D. 90°
, Rationale: sp hybridization gives linear geometry with 180° bond angles.
10. Which of the following is a valid resonance structure?
A. One with more formal charges
B. One with fewer bonds
C. One with all atoms having complete octets
D. One with separated charges
Rationale: The most significant resonance structure has the maximum number of atoms
with complete octets and minimal formal charges.
Chapter 2: Molecular Representations (Questions 11–20)
11. In a bond-line structure, how many carbon atoms are represented by a vertex?
A. 0
B. 1
C. 2
D. 3
Rationale: Each vertex and each endpoint in a bond-line structure represents one
carbon atom (with the appropriate number of hydrogens to complete the octet).
12. How many hydrogens are attached to a carbon with one bond in a bond-line
structure?
A. 1
B. 2
C. 3
D. 4
Rationale: A carbon with one bond has three remaining bonds to hydrogen (CH₃
group).
13. What is the molecular formula of the following bond-line structure: a hexagon
with a circle inside?
EDITION, STUDENT STUDY
GUIDE AND SOLUTIONS –
(KLEIN & STARKEY, 2025) |
ALL 27 CHAPTERS
COVERED
Organic Chemistry 5th Edition (Klein & Starkey, 2025)
Comprehensive Practice Exam | Questions with Bolded
Correct Answers & Detailed Rationales
Based on the official chapter structure covering all 27 chapters
Chapter 1: Electrons, Bonds, and Molecular Properties
(Questions 1–10)
1. What is the formal charge on a carbon atom with three bonds and one lone
pair?
,A. +1
B. 0
C. −1
D. +2
Rationale: Formal charge = Valence electrons − (Lone pair electrons + ½ Bonding
electrons). Carbon has 4 valence electrons. FC = 4 − (2 + 3) = −1. A carbon with three
bonds and one lone pair has a negative formal charge (carbanion).
2. Which of the following molecules has a net dipole moment?
A. CO₂
B. CCl₄
C. CH₂Cl₂
D. BF₃
Rationale: CH₂Cl₂ has a net dipole moment because the C−Cl and C−H bond dipoles do
not cancel. CO₂, CCl₄, and BF₃ are symmetrical and have zero net dipole moments.
3. What is the hybridization of the oxygen atom in water (H₂O)?
A. sp
B. sp³
C. sp²
D. sp³d
Rationale: Oxygen in water has two bonding pairs and two lone pairs, giving it
tetrahedral electron geometry and sp³ hybridization.
4. Which of the following is the strongest type of intermolecular force?
A. London dispersion
B. Dipole-dipole
C. Hydrogen bonding
D. Ion-dipole
Rationale: Hydrogen bonding (when H is bonded to N, O, or F) is stronger than typical
dipole-dipole and London dispersion forces. Ion-dipole is stronger but occurs in
solutions.
5. What is the molecular geometry of a carbon atom with four single bonds?
,A. Trigonal planar
B. Linear
C. Tetrahedral
D. Bent
Rationale: Four bonding pairs around carbon give tetrahedral geometry with bond
angles of 109.5°.
6. Which atomic orbital is higher in energy?
A. 2s
B. 2p
C. They are equal
D. 1s
Rationale: Within the same principal quantum level, p orbitals are higher in energy than
s orbitals due to greater penetration and shielding effects.
7. How many valence electrons does nitrogen have?
A. 3
B. 4
C. 5
D. 7
Rationale: Nitrogen is in Group 15 and has 5 valence electrons (2s² 2p³).
8. Which of the following bonds is most polar?
A. C−H
B. C−C
C. O−H
D. C−O
Rationale: Electronegativity difference: O (3.5) − H (2.1) = 1.4. C−O is 1.0. C−H is 0.4.
C−C is 0. The O−H bond is most polar.
9. What is the bond angle in a molecule with sp hybridization?
A. 109.5°
B. 120°
C. 180°
D. 90°
, Rationale: sp hybridization gives linear geometry with 180° bond angles.
10. Which of the following is a valid resonance structure?
A. One with more formal charges
B. One with fewer bonds
C. One with all atoms having complete octets
D. One with separated charges
Rationale: The most significant resonance structure has the maximum number of atoms
with complete octets and minimal formal charges.
Chapter 2: Molecular Representations (Questions 11–20)
11. In a bond-line structure, how many carbon atoms are represented by a vertex?
A. 0
B. 1
C. 2
D. 3
Rationale: Each vertex and each endpoint in a bond-line structure represents one
carbon atom (with the appropriate number of hydrogens to complete the octet).
12. How many hydrogens are attached to a carbon with one bond in a bond-line
structure?
A. 1
B. 2
C. 3
D. 4
Rationale: A carbon with one bond has three remaining bonds to hydrogen (CH₃
group).
13. What is the molecular formula of the following bond-line structure: a hexagon
with a circle inside?
