Organic Chemistry Study Companion:
One Hundred Solved Practice Questions
with Answers and Rationales Covering
Fundamental Concepts, Alkenes,
Alkynes, Aromaticity, Substitution,
Elimination, Carbonyl Chemistry,
Amines, Carboxylic Acids, Derivatives,
Biomolecules, Spectroscopy,
Stereochemistry, Reaction Mechanisms,
Synthesis, and Multi-Step Problem
Solving for Exam Preparation
,Q: How many sigma and pi bonds are in
ethylene, C₂H₄?
A: 5 sigma, 1 pi.
R: Four C–H bonds and one C–C bond are
sigma; the C=C also has one pi bond.
1. Q: What is the hybridization of
carbon in formaldehyde, H₂C=O?
A: sp².
R: The carbon has three sigma bonds
and one pi bond, giving trigonal planar
geometry.
2. Q: What is the formal charge on
nitrogen in NH₄⁺?
A: +1.
R: FC = valence electrons − nonbonding
, electrons − ½ bonding electrons = 5 − 0
− 4 = +1.
3. Q: Which is the stronger acid: ethanol
or acetic acid?
A: Acetic acid.
R: Its conjugate base, acetate, is
resonance-stabilized, making
deprotonation more favorable.
4. Q: What does a lower pKa indicate?
A: A stronger acid.
R: pKa = −log Ka; larger Ka means
stronger acid and lower pKa.
5. Q: Is water amphoteric?
A: Yes.
R: Water can donate a proton to act as
, an acid or accept a proton to act as a
base.
6. Q: What is the most stable
conformation of butane?
A: Anti conformation.
R: The methyl groups are 180° apart,
minimizing steric strain.
7. Q: Which is lower in energy: eclipsed
or staggered ethane?
A: Staggered.
R: Staggered conformations minimize
torsional strain between C–H bonds.
8. Q: What are constitutional isomers?
A: Compounds with the same
molecular formula but different
One Hundred Solved Practice Questions
with Answers and Rationales Covering
Fundamental Concepts, Alkenes,
Alkynes, Aromaticity, Substitution,
Elimination, Carbonyl Chemistry,
Amines, Carboxylic Acids, Derivatives,
Biomolecules, Spectroscopy,
Stereochemistry, Reaction Mechanisms,
Synthesis, and Multi-Step Problem
Solving for Exam Preparation
,Q: How many sigma and pi bonds are in
ethylene, C₂H₄?
A: 5 sigma, 1 pi.
R: Four C–H bonds and one C–C bond are
sigma; the C=C also has one pi bond.
1. Q: What is the hybridization of
carbon in formaldehyde, H₂C=O?
A: sp².
R: The carbon has three sigma bonds
and one pi bond, giving trigonal planar
geometry.
2. Q: What is the formal charge on
nitrogen in NH₄⁺?
A: +1.
R: FC = valence electrons − nonbonding
, electrons − ½ bonding electrons = 5 − 0
− 4 = +1.
3. Q: Which is the stronger acid: ethanol
or acetic acid?
A: Acetic acid.
R: Its conjugate base, acetate, is
resonance-stabilized, making
deprotonation more favorable.
4. Q: What does a lower pKa indicate?
A: A stronger acid.
R: pKa = −log Ka; larger Ka means
stronger acid and lower pKa.
5. Q: Is water amphoteric?
A: Yes.
R: Water can donate a proton to act as
, an acid or accept a proton to act as a
base.
6. Q: What is the most stable
conformation of butane?
A: Anti conformation.
R: The methyl groups are 180° apart,
minimizing steric strain.
7. Q: Which is lower in energy: eclipsed
or staggered ethane?
A: Staggered.
R: Staggered conformations minimize
torsional strain between C–H bonds.
8. Q: What are constitutional isomers?
A: Compounds with the same
molecular formula but different
