CHEM 210 FINAL EXAM ACTUAL EXAM 2026 | UPDATED QUESTIONS AND
CORRECT ANSWERS | GRADED A+ | VERIFIED ANSWERS | JUST RELEASED
Question 1
According to bonding patterns, how many bonds and valence electrons does a neutral
Boron atom (Group 13/3A) typically possess?
A) 4 bonds, 0 lone pairs
B) 3 bonds, 0 lone pairs (6 total electrons)
C) 3 bonds, 1 lone pair (8 total electrons)
D) 5 bonds, 0 lone pairs
Correct Answer: B) 3 bonds, 0 lone pairs (6 total electrons)
Rationale: According to the "Bonding Patterns" section of your notes, Group 13/3A elements
(like Boron) have 3 valence electrons. They typically form 3 bonds. This results in an "open
shell" configuration with only 6 total electrons (3 owned + 3 shared), rather than a full octet.
Question 2
Which of the following is the correct formula for calculating Units of Unsaturation?
A)
((2𝑛 + 2) − 𝑚 + 𝑡)/2
B)
((2𝑛 + 2) + 𝑚 − 𝑡)/2
C)
(2𝑛 + 2)/2
D)
2𝑛 + 2 − 𝑚 + 𝑡
Correct Answer: A)
((2𝑛 + 2) − 𝑚 + 𝑡)/2
, 2
Rationale: The notes define the formula explicitly: calculate the saturated reference
(2𝑛+2)
, subtract the number of monovalents (
𝑚
, like H or Halogens), add the number of trivalents (
𝑡
, like Nitrogen), and divide the total by 2.
Question 3
In a curved arrow notation mechanism, the arrow must always start at:
A) The positive charge
B) The proton (H)
C) The electron source
D) The electrophile
Correct Answer: C) The electron source
Rationale: Under "Curved Arrow Notation," the notes state: "Start at the electron source and end
where they're going." Arrows track the movement of electron density (lone pairs or bonds), not
the movement of atoms or positive charges.
Question 4
Rank the following factors influencing bond length from most influential to least
influential:
A) Bond Order > Electronegativity > Atomic Radius > Delocalization
B) Atomic Radius > Bond Order > Electronegativity > Delocalization
C) Electronegativity > Bond Order > Atomic Radius > Delocalization
D) Delocalization > Atomic Radius > Bond Order > Electronegativity
Correct Answer: B) Atomic Radius > Bond Order > Electronegativity > Delocalization
Rationale: The notes provide a "Ranked List of Factors" for bond lengths:
, 3
1. Atomic Radius (e.g., H is much smaller than Si).
2. Bond Order (Triple < Double < Single).
3. Electronegativity (Hybridization effects).
4. Delocalization.
Question 5
Which of the following statements regarding pKa and acid strength is TRUE?
A) A lower pKa indicates a weaker acid.
B) sp3 hybridized carbons are more acidic than sp hybridized carbons.
C) A change in 1 pKa unit represents a 10-fold change in acidity.
D) Larger atoms generally form stronger bonds with hydrogen, making them less acidic.
Correct Answer: C) A change in 1 pKa unit represents a 10-fold change in acidity.
Rationale: The "Trends in pKa" section states: "note that the change in +/- 1 unit of pKa
represents a 10-fold change in ratio of acid/base." Option A is false (lower pKa = stronger acid).
Option D is false (larger atoms have weaker bonds to H, making them more acidic).
Question 6
When assigning priority for R/S configuration or E/Z isomers, what is the primary rule?
A) Priority is based on the size (volume) of the substituent group.
B) Priority is based on the atomic number of the atom directly attached.
C) Priority is based on electronegativity.
D) Priority is determined by the number of hydrogens attached.
Correct Answer: B) Priority is based on the atomic number of the atom directly attached.
Rationale: Under "Sources of Stereoisomerism," the notes describe assigning conformation by
making priorities. In standard Cahn-Ingold-Prelog rules (implied by "count highest to lowest"),
priority is determined by atomic number (e.g., Br > Cl > C > H).
Question 7
A molecule that has chiral centers but is achiral overall due to an internal plane of
symmetry is called:
, 4
A) An Enantiomer
B) A Racemic Mixture
C) A Diastereomer
D) A Meso Compound
Correct Answer: D) A Meso Compound
Rationale: The notes define a Meso Compound as an "Achiral stereoisomer in a set that has
chiral members." For example, if a molecule has two stereocenters (e.g., R,S) that cancel each
other out due to symmetry, it is meso and optically inactive.
Question 8
In a Newman projection, which interaction allows for hydrogen bonding stabilization that
might outweigh steric strain?
A) Anti conformation
B) Eclipsed conformation
C) Gauche conformation
D) Para conformation
Correct Answer: C) Gauche conformation
Rationale: Under "Interesting Phenomenon with Steric Interactions and H-Bonds," the notes
state this "only happens in gauche." In the gauche position, groups are close enough (60 degrees)
to hydrogen bond, which can stabilize the molecule despite the steric crowding.
Question 9
When a cyclohexane chair performs a "chair flip," what happens to the substituents?
A) Axial positions become equatorial; Up remains Up.
B) Axial positions become equatorial; Up becomes Down.
C) Equatorial positions remain equatorial; Up becomes Down.
D) No change occurs in axial/equatorial designation.
Correct Answer: A) Axial positions become equatorial; Up remains Up.
Rationale: The "Chair Flips" section states: "when the chair flips, axial becomes equatorial, but
up/down doesn't change." The directional orientation relative to the ring plane is preserved, but
the steric environment (axial vs. equatorial) inverts.
CORRECT ANSWERS | GRADED A+ | VERIFIED ANSWERS | JUST RELEASED
Question 1
According to bonding patterns, how many bonds and valence electrons does a neutral
Boron atom (Group 13/3A) typically possess?
A) 4 bonds, 0 lone pairs
B) 3 bonds, 0 lone pairs (6 total electrons)
C) 3 bonds, 1 lone pair (8 total electrons)
D) 5 bonds, 0 lone pairs
Correct Answer: B) 3 bonds, 0 lone pairs (6 total electrons)
Rationale: According to the "Bonding Patterns" section of your notes, Group 13/3A elements
(like Boron) have 3 valence electrons. They typically form 3 bonds. This results in an "open
shell" configuration with only 6 total electrons (3 owned + 3 shared), rather than a full octet.
Question 2
Which of the following is the correct formula for calculating Units of Unsaturation?
A)
((2𝑛 + 2) − 𝑚 + 𝑡)/2
B)
((2𝑛 + 2) + 𝑚 − 𝑡)/2
C)
(2𝑛 + 2)/2
D)
2𝑛 + 2 − 𝑚 + 𝑡
Correct Answer: A)
((2𝑛 + 2) − 𝑚 + 𝑡)/2
, 2
Rationale: The notes define the formula explicitly: calculate the saturated reference
(2𝑛+2)
, subtract the number of monovalents (
𝑚
, like H or Halogens), add the number of trivalents (
𝑡
, like Nitrogen), and divide the total by 2.
Question 3
In a curved arrow notation mechanism, the arrow must always start at:
A) The positive charge
B) The proton (H)
C) The electron source
D) The electrophile
Correct Answer: C) The electron source
Rationale: Under "Curved Arrow Notation," the notes state: "Start at the electron source and end
where they're going." Arrows track the movement of electron density (lone pairs or bonds), not
the movement of atoms or positive charges.
Question 4
Rank the following factors influencing bond length from most influential to least
influential:
A) Bond Order > Electronegativity > Atomic Radius > Delocalization
B) Atomic Radius > Bond Order > Electronegativity > Delocalization
C) Electronegativity > Bond Order > Atomic Radius > Delocalization
D) Delocalization > Atomic Radius > Bond Order > Electronegativity
Correct Answer: B) Atomic Radius > Bond Order > Electronegativity > Delocalization
Rationale: The notes provide a "Ranked List of Factors" for bond lengths:
, 3
1. Atomic Radius (e.g., H is much smaller than Si).
2. Bond Order (Triple < Double < Single).
3. Electronegativity (Hybridization effects).
4. Delocalization.
Question 5
Which of the following statements regarding pKa and acid strength is TRUE?
A) A lower pKa indicates a weaker acid.
B) sp3 hybridized carbons are more acidic than sp hybridized carbons.
C) A change in 1 pKa unit represents a 10-fold change in acidity.
D) Larger atoms generally form stronger bonds with hydrogen, making them less acidic.
Correct Answer: C) A change in 1 pKa unit represents a 10-fold change in acidity.
Rationale: The "Trends in pKa" section states: "note that the change in +/- 1 unit of pKa
represents a 10-fold change in ratio of acid/base." Option A is false (lower pKa = stronger acid).
Option D is false (larger atoms have weaker bonds to H, making them more acidic).
Question 6
When assigning priority for R/S configuration or E/Z isomers, what is the primary rule?
A) Priority is based on the size (volume) of the substituent group.
B) Priority is based on the atomic number of the atom directly attached.
C) Priority is based on electronegativity.
D) Priority is determined by the number of hydrogens attached.
Correct Answer: B) Priority is based on the atomic number of the atom directly attached.
Rationale: Under "Sources of Stereoisomerism," the notes describe assigning conformation by
making priorities. In standard Cahn-Ingold-Prelog rules (implied by "count highest to lowest"),
priority is determined by atomic number (e.g., Br > Cl > C > H).
Question 7
A molecule that has chiral centers but is achiral overall due to an internal plane of
symmetry is called:
, 4
A) An Enantiomer
B) A Racemic Mixture
C) A Diastereomer
D) A Meso Compound
Correct Answer: D) A Meso Compound
Rationale: The notes define a Meso Compound as an "Achiral stereoisomer in a set that has
chiral members." For example, if a molecule has two stereocenters (e.g., R,S) that cancel each
other out due to symmetry, it is meso and optically inactive.
Question 8
In a Newman projection, which interaction allows for hydrogen bonding stabilization that
might outweigh steric strain?
A) Anti conformation
B) Eclipsed conformation
C) Gauche conformation
D) Para conformation
Correct Answer: C) Gauche conformation
Rationale: Under "Interesting Phenomenon with Steric Interactions and H-Bonds," the notes
state this "only happens in gauche." In the gauche position, groups are close enough (60 degrees)
to hydrogen bond, which can stabilize the molecule despite the steric crowding.
Question 9
When a cyclohexane chair performs a "chair flip," what happens to the substituents?
A) Axial positions become equatorial; Up remains Up.
B) Axial positions become equatorial; Up becomes Down.
C) Equatorial positions remain equatorial; Up becomes Down.
D) No change occurs in axial/equatorial designation.
Correct Answer: A) Axial positions become equatorial; Up remains Up.
Rationale: The "Chair Flips" section states: "when the chair flips, axial becomes equatorial, but
up/down doesn't change." The directional orientation relative to the ring plane is preserved, but
the steric environment (axial vs. equatorial) inverts.
