CHEM 210 BIOCHEMISTRY MODULES 1-8 CUMULATIVE
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Module 1: Atomic Structure, Chemical Bonding & Periodic Trends (Questions 1-15)
Question 1
An atom of carbon-14 has 6 protons. How many neutrons does this isotope contain?
A. 6 neutrons
B. 8 neutrons [CORRECT]
C. 14 neutrons
D. 20 neutrons
Rationale: The mass number (14) equals protons plus neutrons. Therefore, neutrons =
14 - 6 = 8. Carbon-14 is a radioactive isotope used in radiocarbon dating. Option A
confuses protons with neutrons; C uses the mass number as neutron count; D
incorrectly adds protons and mass number.
Correct Answer: B
Question 2
A nurse is reviewing electron configuration for elements relevant to biochemistry. Which
is the correct electron configuration for oxygen (atomic number 8)?
A. 1s² 2s² 2p²
B. 1s² 2s² 2p⁴ [CORRECT]
C. 1s² 2s² 2p⁶ 3s²
D. 1s² 2s² 2p⁶
,Rationale: Oxygen has 8 electrons. Following the Aufbau principle, the configuration is
1s² 2s² 2p⁴. Option A has only 6 electrons. Option C is magnesium (12 electrons).
Option D is neon (10 electrons), a noble gas configuration.
Correct Answer: B
Question 3
In a water molecule (H₂O), the oxygen atom has an electronegativity of 3.44 and
hydrogen has 2.20. What type of bond exists between oxygen and hydrogen?
A. Nonpolar covalent bond
B. Polar covalent bond [CORRECT]
C. Ionic bond
D. Metallic bond
Rationale: The electronegativity difference (3.44 - 2.20 = 1.24) falls within the polar
covalent range (0.4-1.7). Water's polarity is fundamental to its biological properties. A
difference below 0.4 would be nonpolar covalent; above 1.7 would be ionic. Metallic
bonds do not occur in water.
Correct Answer: B
Question 4
Which periodic trend correctly describes the relationship between atomic radius and
position in the periodic table?
A. Atomic radius increases across a period (left to right) and increases down a group
B. Atomic radius decreases across a period (left to right) and increases down a group
[CORRECT]
C. Atomic radius increases across a period and decreases down a group
D. Atomic radius remains constant across periods and groups
,Rationale: Atomic radius decreases across a period due to increasing nuclear charge
pulling electrons closer, and increases down a group as additional electron shells are
added. This trend affects ionic size and bonding characteristics important in
biochemistry.
Correct Answer: B
Question 5
A biochemistry student is analyzing the bonds in an amino acid. Which interaction is
primarily responsible for maintaining the tertiary structure of proteins?
A. Peptide bonds between adjacent amino acids
B. Hydrophobic interactions, hydrogen bonds, disulfide bridges, and ionic bonds
between R groups [CORRECT]
C. Phosphodiester bonds between nucleotides
D. Glycosidic bonds between carbohydrate units
Rationale: Tertiary structure involves interactions between amino acid side chains (R
groups), including hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide
bridges. Peptide bonds define primary structure. Phosphodiester and glycosidic bonds
are found in nucleic acids and carbohydrates, respectively.
Correct Answer: B
Question 6
Which type of chemical bond is formed when sodium (Na) donates an electron to
chlorine (Cl)?
A. Covalent bond
B. Hydrogen bond
C. Ionic bond [CORRECT]
D. Van der Waals interaction
, Rationale: Sodium (electronegativity 0.93) and chlorine (3.16) have a large
electronegativity difference (>1.7), resulting in electron transfer and ionic bond
formation (Na⁺Cl⁻). Covalent bonds involve electron sharing. Hydrogen bonds and van
der Waals forces are intermolecular, not intramolecular bonds.
Correct Answer: C
Question 7
In biochemistry, van der Waals interactions are best described as:
A. Strong covalent bonds between nonpolar molecules
B. Weak, transient attractive forces due to fluctuating electron distributions [CORRECT]
C. Permanent dipole-dipole interactions between polar molecules
D. Ionic attractions between oppositely charged ions
Rationale: Van der Waals (London dispersion) forces are weak, transient attractions
caused by temporary fluctuations in electron density creating instantaneous dipoles.
Though individually weak, they are collectively significant in protein folding and
membrane structure. They are not covalent, permanent dipole, or ionic interactions.
Correct Answer: B
Question 8
Which element has the highest first ionization energy among the following biologically
important elements?
A. Sodium (Na)
B. Carbon (C)
C. Oxygen (O) [CORRECT]
D. Calcium (Ca)
EXAM 2026/2027 | Verified Questions & Answers | Complete
Review | Pass Guaranteed - A+ Graded
Module 1: Atomic Structure, Chemical Bonding & Periodic Trends (Questions 1-15)
Question 1
An atom of carbon-14 has 6 protons. How many neutrons does this isotope contain?
A. 6 neutrons
B. 8 neutrons [CORRECT]
C. 14 neutrons
D. 20 neutrons
Rationale: The mass number (14) equals protons plus neutrons. Therefore, neutrons =
14 - 6 = 8. Carbon-14 is a radioactive isotope used in radiocarbon dating. Option A
confuses protons with neutrons; C uses the mass number as neutron count; D
incorrectly adds protons and mass number.
Correct Answer: B
Question 2
A nurse is reviewing electron configuration for elements relevant to biochemistry. Which
is the correct electron configuration for oxygen (atomic number 8)?
A. 1s² 2s² 2p²
B. 1s² 2s² 2p⁴ [CORRECT]
C. 1s² 2s² 2p⁶ 3s²
D. 1s² 2s² 2p⁶
,Rationale: Oxygen has 8 electrons. Following the Aufbau principle, the configuration is
1s² 2s² 2p⁴. Option A has only 6 electrons. Option C is magnesium (12 electrons).
Option D is neon (10 electrons), a noble gas configuration.
Correct Answer: B
Question 3
In a water molecule (H₂O), the oxygen atom has an electronegativity of 3.44 and
hydrogen has 2.20. What type of bond exists between oxygen and hydrogen?
A. Nonpolar covalent bond
B. Polar covalent bond [CORRECT]
C. Ionic bond
D. Metallic bond
Rationale: The electronegativity difference (3.44 - 2.20 = 1.24) falls within the polar
covalent range (0.4-1.7). Water's polarity is fundamental to its biological properties. A
difference below 0.4 would be nonpolar covalent; above 1.7 would be ionic. Metallic
bonds do not occur in water.
Correct Answer: B
Question 4
Which periodic trend correctly describes the relationship between atomic radius and
position in the periodic table?
A. Atomic radius increases across a period (left to right) and increases down a group
B. Atomic radius decreases across a period (left to right) and increases down a group
[CORRECT]
C. Atomic radius increases across a period and decreases down a group
D. Atomic radius remains constant across periods and groups
,Rationale: Atomic radius decreases across a period due to increasing nuclear charge
pulling electrons closer, and increases down a group as additional electron shells are
added. This trend affects ionic size and bonding characteristics important in
biochemistry.
Correct Answer: B
Question 5
A biochemistry student is analyzing the bonds in an amino acid. Which interaction is
primarily responsible for maintaining the tertiary structure of proteins?
A. Peptide bonds between adjacent amino acids
B. Hydrophobic interactions, hydrogen bonds, disulfide bridges, and ionic bonds
between R groups [CORRECT]
C. Phosphodiester bonds between nucleotides
D. Glycosidic bonds between carbohydrate units
Rationale: Tertiary structure involves interactions between amino acid side chains (R
groups), including hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide
bridges. Peptide bonds define primary structure. Phosphodiester and glycosidic bonds
are found in nucleic acids and carbohydrates, respectively.
Correct Answer: B
Question 6
Which type of chemical bond is formed when sodium (Na) donates an electron to
chlorine (Cl)?
A. Covalent bond
B. Hydrogen bond
C. Ionic bond [CORRECT]
D. Van der Waals interaction
, Rationale: Sodium (electronegativity 0.93) and chlorine (3.16) have a large
electronegativity difference (>1.7), resulting in electron transfer and ionic bond
formation (Na⁺Cl⁻). Covalent bonds involve electron sharing. Hydrogen bonds and van
der Waals forces are intermolecular, not intramolecular bonds.
Correct Answer: C
Question 7
In biochemistry, van der Waals interactions are best described as:
A. Strong covalent bonds between nonpolar molecules
B. Weak, transient attractive forces due to fluctuating electron distributions [CORRECT]
C. Permanent dipole-dipole interactions between polar molecules
D. Ionic attractions between oppositely charged ions
Rationale: Van der Waals (London dispersion) forces are weak, transient attractions
caused by temporary fluctuations in electron density creating instantaneous dipoles.
Though individually weak, they are collectively significant in protein folding and
membrane structure. They are not covalent, permanent dipole, or ionic interactions.
Correct Answer: B
Question 8
Which element has the highest first ionization energy among the following biologically
important elements?
A. Sodium (Na)
B. Carbon (C)
C. Oxygen (O) [CORRECT]
D. Calcium (Ca)
