CHEM 103: GENERAL ORGANIC CHEMISTRY
Module 1 to 6 Exams,
Final Exam and Lab Exam 1 to 6 with Verified
Answers Package Deal for Learning
(Latest Update) 2025/2026.
1. Which of the following is the correct definition of organic chemistry?
a) The study of carbon-containing compounds
b) The study of compounds derived from living organisms only
c) The study of all elements except metals
d) The study of hydrocarbons and their derivatives
Answer: d) The study of hydrocarbons and their derivatives
Rationale: While organic chemistry primarily focuses on carbon compounds, the most precise
definition is the study of hydrocarbons (compounds of carbon and hydrogen) and their
derivatives. Option A is too broad (carbides, carbonates are inorganic).
2. What is the hybridization state of the carbon atom in methane (CH₄)?
a) sp
b) sp²
c) sp³
d) dsp²
Answer: c) sp³
Rationale: Methane has four sigma bonds and no lone pairs on carbon. To form four
equivalent bonds, carbon hybridizes one s and three p orbitals to form four sp³ hybrid orbitals
oriented tetrahedrally.
,3. Which functional group is present in an aldehyde?
a) -OH
b) -COOH
c) -CHO
d) -CO-
Answer: c) -CHO
Rationale: The aldehyde functional group consists of a carbonyl group (C=O) bonded to at
least one hydrogen atom, represented as -CHO. Option D (-CO-) represents a ketone without
specifying the attachment.
4. A compound has the molecular formula C₃H₈O. It is soluble in water and produces
bubbles when reacted with sodium metal. What functional group is present?
a) Ether
b) Alcohol
c) Ketone
d) Alkene
Answer: b) Alcohol
Rationale: Solubility in water indicates polarity. The reaction with sodium metal producing
hydrogen gas (bubbles) is a characteristic test for the presence of an acidic hydrogen,
specifically in alcohols (-OH) and carboxylic acids. Since C₃H₈O fits propanol, the correct
functional group is alcohol.
5. Which of the following represents a tertiary alcohol?
a) 2-methylpropan-2-ol
b) Butan-1-ol
c) Butan-2-ol
d) 2-methylpropan-1-ol
Answer: a) 2-methylpropan-2-ol
*Rationale: A tertiary alcohol has the carbon bearing the -OH group attached to three other
carbon atoms. 2-methylpropan-2-ol has the central carbon (C-OH) bonded to three methyl
groups.*
,MODULE 2: Alkanes, Alkenes, Alkynes & Stereochemistry
6. What is the IUPAC name for (CH₃)₂CHCH₂CH₃?
a) Pentane
b) 2-methylbutane
c) 3-methylbutane
d) Isopentane
Answer: b) 2-methylbutane
*Rationale: The longest carbon chain contains 4 carbons (butane). A methyl group is
attached to the second carbon, giving the name 2-methylbutane. Isopentane is a common
name.*
7. Which type of isomerism is exhibited by but-2-ene?
a) Chain isomerism
b) Position isomerism
c) Geometric isomerism
d) Optical isomerism
Answer: c) Geometric isomerism
*Rationale: But-2-ene (CH₃CH=CHCH₃) has a double bond with two different groups on each
carbon (H and CH₃). This restricts rotation, allowing cis (both CH₃ on same side) and trans
(CH₃ on opposite sides) isomers.*
8. Which of the following is the most stable conformation of cyclohexane?
a) Boat
b) Twist-boat
c) Chair
d) Half-chair
Answer: c) Chair
Rationale: The chair conformation of cyclohexane is the most stable because it has zero
torsional strain (all bonds staggered) and minimal angle strain (bond angles ~109.5°).
9. A compound with the molecular formula C₄H₈ reacts with Br₂/CCl₄ to decolorize the
solution. Which structure is NOT possible for this compound?
a) But-1-ene
, b) Cyclobutane
c) But-2-ene
d) Methylpropene
Answer: b) Cyclobutane
Rationale: Decolorization of bromine water tests for unsaturation (double or triple bonds).
Cyclobutane has the formula C₄H₈ but is a saturated cycloalkane with only single bonds; it
does not decolorize bromine under standard conditions without UV light (free radical
substitution).
10. What is the product of the hydrogenation of propyne with excess H₂ in the presence of
a Lindlar catalyst?
a) Propane
b) Propene
c) Propyne
d) 1-propanol
Answer: a) Propane
Rationale: Hydrogenation with excess H₂ and a metal catalyst (Ni, Pd, Pt) leads to complete
saturation. Lindlar catalyst is used to stop at the alkene stage, but the question specifies
excess H₂ with a standard catalyst (implied by "excess" and no mention of Lindlar), yielding
the alkane.
MODULE 3: Aromatic Compounds & Reactions
11. Which of the following compounds is aromatic according to Hückel’s rule?
a) Cyclooctatetraene
b) Benzene
c) Cyclobutadiene
d) 1,3,5-hexatriene
Answer: b) Benzene
*Rationale: Hückel’s rule states that aromatic compounds must have (4n+2) π electrons, be
cyclic, planar, and fully conjugated. Benzene has 6 π electrons (n=1). Cyclooctatetraene is
non-planar (tub-shaped), and cyclobutadiene has 4 π electrons (anti-aromatic).*
Module 1 to 6 Exams,
Final Exam and Lab Exam 1 to 6 with Verified
Answers Package Deal for Learning
(Latest Update) 2025/2026.
1. Which of the following is the correct definition of organic chemistry?
a) The study of carbon-containing compounds
b) The study of compounds derived from living organisms only
c) The study of all elements except metals
d) The study of hydrocarbons and their derivatives
Answer: d) The study of hydrocarbons and their derivatives
Rationale: While organic chemistry primarily focuses on carbon compounds, the most precise
definition is the study of hydrocarbons (compounds of carbon and hydrogen) and their
derivatives. Option A is too broad (carbides, carbonates are inorganic).
2. What is the hybridization state of the carbon atom in methane (CH₄)?
a) sp
b) sp²
c) sp³
d) dsp²
Answer: c) sp³
Rationale: Methane has four sigma bonds and no lone pairs on carbon. To form four
equivalent bonds, carbon hybridizes one s and three p orbitals to form four sp³ hybrid orbitals
oriented tetrahedrally.
,3. Which functional group is present in an aldehyde?
a) -OH
b) -COOH
c) -CHO
d) -CO-
Answer: c) -CHO
Rationale: The aldehyde functional group consists of a carbonyl group (C=O) bonded to at
least one hydrogen atom, represented as -CHO. Option D (-CO-) represents a ketone without
specifying the attachment.
4. A compound has the molecular formula C₃H₈O. It is soluble in water and produces
bubbles when reacted with sodium metal. What functional group is present?
a) Ether
b) Alcohol
c) Ketone
d) Alkene
Answer: b) Alcohol
Rationale: Solubility in water indicates polarity. The reaction with sodium metal producing
hydrogen gas (bubbles) is a characteristic test for the presence of an acidic hydrogen,
specifically in alcohols (-OH) and carboxylic acids. Since C₃H₈O fits propanol, the correct
functional group is alcohol.
5. Which of the following represents a tertiary alcohol?
a) 2-methylpropan-2-ol
b) Butan-1-ol
c) Butan-2-ol
d) 2-methylpropan-1-ol
Answer: a) 2-methylpropan-2-ol
*Rationale: A tertiary alcohol has the carbon bearing the -OH group attached to three other
carbon atoms. 2-methylpropan-2-ol has the central carbon (C-OH) bonded to three methyl
groups.*
,MODULE 2: Alkanes, Alkenes, Alkynes & Stereochemistry
6. What is the IUPAC name for (CH₃)₂CHCH₂CH₃?
a) Pentane
b) 2-methylbutane
c) 3-methylbutane
d) Isopentane
Answer: b) 2-methylbutane
*Rationale: The longest carbon chain contains 4 carbons (butane). A methyl group is
attached to the second carbon, giving the name 2-methylbutane. Isopentane is a common
name.*
7. Which type of isomerism is exhibited by but-2-ene?
a) Chain isomerism
b) Position isomerism
c) Geometric isomerism
d) Optical isomerism
Answer: c) Geometric isomerism
*Rationale: But-2-ene (CH₃CH=CHCH₃) has a double bond with two different groups on each
carbon (H and CH₃). This restricts rotation, allowing cis (both CH₃ on same side) and trans
(CH₃ on opposite sides) isomers.*
8. Which of the following is the most stable conformation of cyclohexane?
a) Boat
b) Twist-boat
c) Chair
d) Half-chair
Answer: c) Chair
Rationale: The chair conformation of cyclohexane is the most stable because it has zero
torsional strain (all bonds staggered) and minimal angle strain (bond angles ~109.5°).
9. A compound with the molecular formula C₄H₈ reacts with Br₂/CCl₄ to decolorize the
solution. Which structure is NOT possible for this compound?
a) But-1-ene
, b) Cyclobutane
c) But-2-ene
d) Methylpropene
Answer: b) Cyclobutane
Rationale: Decolorization of bromine water tests for unsaturation (double or triple bonds).
Cyclobutane has the formula C₄H₈ but is a saturated cycloalkane with only single bonds; it
does not decolorize bromine under standard conditions without UV light (free radical
substitution).
10. What is the product of the hydrogenation of propyne with excess H₂ in the presence of
a Lindlar catalyst?
a) Propane
b) Propene
c) Propyne
d) 1-propanol
Answer: a) Propane
Rationale: Hydrogenation with excess H₂ and a metal catalyst (Ni, Pd, Pt) leads to complete
saturation. Lindlar catalyst is used to stop at the alkene stage, but the question specifies
excess H₂ with a standard catalyst (implied by "excess" and no mention of Lindlar), yielding
the alkane.
MODULE 3: Aromatic Compounds & Reactions
11. Which of the following compounds is aromatic according to Hückel’s rule?
a) Cyclooctatetraene
b) Benzene
c) Cyclobutadiene
d) 1,3,5-hexatriene
Answer: b) Benzene
*Rationale: Hückel’s rule states that aromatic compounds must have (4n+2) π electrons, be
cyclic, planar, and fully conjugated. Benzene has 6 π electrons (n=1). Cyclooctatetraene is
non-planar (tub-shaped), and cyclobutadiene has 4 π electrons (anti-aromatic).*
