CHEM 219 Final Exam Prep:
Comprehensive Organic Chemistry
Questions with Answers & Rationales |
Portage Learning
1. How many hydrogen atoms are typically bonded to each
internal carbon atom in a straight-chain alkane?
A) 1
B) 2
C) 3
D) 4
Answer: B | Rationale: Each internal carbon in an alkane is
bonded to two other carbon atoms. Carbon requires four
bonds to complete its octet, so it needs two additional
bonds, typically to hydrogen atoms. This is a fundamental
concept in understanding the structure of alkanes .
2. What is the definition of a constitutional isomer?
A) Two compounds with the same molecular formula but
different connectivity between atoms.
B) Two compounds with the same connectivity but different
spatial arrangement.
C) Two compounds with different molecular formulas and
different connectivity.
D) Two compounds that are mirror images of each other.
,Answer: A | Rationale: Constitutional isomers are different
chemical compounds with the same molecular formula but
different connectivity of their atoms. This is in contrast to
stereoisomers, which have the same connectivity but differ
in spatial arrangement .
3. Which of the following pairs of elements would form a
purely covalent (nonpolar) bond?
A) O-H
B) N-N
C) K-S
D) Cl-Br
Answer: B | Rationale: A purely covalent bond occurs when
the electronegativity difference between the two atoms is 0.
The N-N bond involves two identical atoms, so the electrons
are shared equally, making it purely covalent. The other
pairs have electronegativity differences that result in polar
covalent bonds .
4. What is the general formula for a cycloalkane?
A) CₙH₂ₙ₊₂
B) CₙH₂ₙ
C) CₙH₂ₙ₋₂
D) CₙHₙ
Answer: B | Rationale: Cycloalkanes have the general
formula CₙH₂ₙ, which is two fewer hydrogens than the
,corresponding acyclic alkane (CₙH₂ₙ₊₂) because the ring
formation eliminates two hydrogens.
5. Based on the electronegativity difference (ΔEN = 1.4), the
O-H bond is best classified as:
A) Ionic
B) Purely covalent
C) Polar covalent
D) Metallic
Answer: C | Rationale: An electronegativity difference
between 0.4 and 1.7 generally indicates a polar covalent
bond. The O-H bond has a significant electronegativity
difference, making it polar covalent .
6. Which of the following carbon skeletons is classified as
branched?
A) A straight chain of four carbons
B) A chain where one carbon is attached to three other
carbons
C) A ring of six carbons
D) A chain of three carbons with no branches
Answer: B | Rationale: A branched carbon skeleton has at
least one carbon atom connected to three or more other
carbon atoms, creating a branch point. Linear (continuous)
chains have carbons in a straight line, and cyclic structures
form rings .
, 7. True or False: Moving single bonds in electron resonance
is allowed, as that would change the connectivity of the
atoms in the molecule.
A) True
B) False
Answer: B | Rationale: In resonance, only the distribution of
π electrons, lone pair electrons, or formal charges is
altered. The σ (single) bonds represent the fundamental
connectivity of atoms, which must remain unchanged.
Changing single bonds would create a different isomer, not
a resonance structure .
8. What does the term "molecular formula" convey about a
compound?
A) The type and number of different atoms present
B) The pattern of connectivity between atoms
C) The three-dimensional shape of the molecule
D) The arrangement of electrons
Answer: A | Rationale: A molecular formula (e.g., C₆H₁₂O₆)
indicates the exact number and types of atoms in a
molecule. It does not show connectivity (structural formula),
shape (VSEPR), or electron arrangement (Lewis structure).
9. Which of the following objects is chiral?
A) A simple wine glass
Comprehensive Organic Chemistry
Questions with Answers & Rationales |
Portage Learning
1. How many hydrogen atoms are typically bonded to each
internal carbon atom in a straight-chain alkane?
A) 1
B) 2
C) 3
D) 4
Answer: B | Rationale: Each internal carbon in an alkane is
bonded to two other carbon atoms. Carbon requires four
bonds to complete its octet, so it needs two additional
bonds, typically to hydrogen atoms. This is a fundamental
concept in understanding the structure of alkanes .
2. What is the definition of a constitutional isomer?
A) Two compounds with the same molecular formula but
different connectivity between atoms.
B) Two compounds with the same connectivity but different
spatial arrangement.
C) Two compounds with different molecular formulas and
different connectivity.
D) Two compounds that are mirror images of each other.
,Answer: A | Rationale: Constitutional isomers are different
chemical compounds with the same molecular formula but
different connectivity of their atoms. This is in contrast to
stereoisomers, which have the same connectivity but differ
in spatial arrangement .
3. Which of the following pairs of elements would form a
purely covalent (nonpolar) bond?
A) O-H
B) N-N
C) K-S
D) Cl-Br
Answer: B | Rationale: A purely covalent bond occurs when
the electronegativity difference between the two atoms is 0.
The N-N bond involves two identical atoms, so the electrons
are shared equally, making it purely covalent. The other
pairs have electronegativity differences that result in polar
covalent bonds .
4. What is the general formula for a cycloalkane?
A) CₙH₂ₙ₊₂
B) CₙH₂ₙ
C) CₙH₂ₙ₋₂
D) CₙHₙ
Answer: B | Rationale: Cycloalkanes have the general
formula CₙH₂ₙ, which is two fewer hydrogens than the
,corresponding acyclic alkane (CₙH₂ₙ₊₂) because the ring
formation eliminates two hydrogens.
5. Based on the electronegativity difference (ΔEN = 1.4), the
O-H bond is best classified as:
A) Ionic
B) Purely covalent
C) Polar covalent
D) Metallic
Answer: C | Rationale: An electronegativity difference
between 0.4 and 1.7 generally indicates a polar covalent
bond. The O-H bond has a significant electronegativity
difference, making it polar covalent .
6. Which of the following carbon skeletons is classified as
branched?
A) A straight chain of four carbons
B) A chain where one carbon is attached to three other
carbons
C) A ring of six carbons
D) A chain of three carbons with no branches
Answer: B | Rationale: A branched carbon skeleton has at
least one carbon atom connected to three or more other
carbon atoms, creating a branch point. Linear (continuous)
chains have carbons in a straight line, and cyclic structures
form rings .
, 7. True or False: Moving single bonds in electron resonance
is allowed, as that would change the connectivity of the
atoms in the molecule.
A) True
B) False
Answer: B | Rationale: In resonance, only the distribution of
π electrons, lone pair electrons, or formal charges is
altered. The σ (single) bonds represent the fundamental
connectivity of atoms, which must remain unchanged.
Changing single bonds would create a different isomer, not
a resonance structure .
8. What does the term "molecular formula" convey about a
compound?
A) The type and number of different atoms present
B) The pattern of connectivity between atoms
C) The three-dimensional shape of the molecule
D) The arrangement of electrons
Answer: A | Rationale: A molecular formula (e.g., C₆H₁₂O₆)
indicates the exact number and types of atoms in a
molecule. It does not show connectivity (structural formula),
shape (VSEPR), or electron arrangement (Lewis structure).
9. Which of the following objects is chiral?
A) A simple wine glass
