CHEM 120 FINAL EXAM (Version 3) – Chamberlain
University Actual Exam – Complete Questions and
Answers with Detailed Rationales – Pass
Guaranteed – A+ Graded
Foundations: Atomic Structure, Bonding & Solutions
Q1: A neutral atom of sulfur has 16 protons. How many electrons does it possess?
A. 8
B. 16 [CORRECT]
C. 32
D. 6
Correct Answer: B
Rationale: The best answer is B because in a neutral atom, the number of electrons
always equals the number of protons, so sulfur carries 16 electrons to balance those 16
positive charges in the nucleus.
Q2: Which element has the highest electronegativity?
A. Sodium
B. Oxygen [CORRECT]
C. Calcium
D. Aluminum
Correct Answer: B
Rationale: This aligns with periodic trends—electronegativity increases as you move up
and to the right on the periodic table, so oxygen pulls electron density toward itself more
strongly than the metals listed here.
Q3: How many valence electrons does a neutral oxygen atom have?
A. 2
,B. 4
C. 6 [CORRECT]
D. 8
Correct Answer: C
Rationale: This is basic atomic structure—oxygen sits in group 16 on the periodic table,
so a neutral atom has six electrons in its outermost shell.
Q4: A bond forms between sodium (electronegativity 0.9) and chlorine (electronegativity
3.0). What type of bond is this?
A. Nonpolar covalent
B. Polar covalent
C. Ionic [CORRECT]
D. Hydrogen
Correct Answer: C
Rationale: The best answer is C because that electronegativity difference of 2.1 is well
above the 1.7 cutoff we use in class, meaning chlorine essentially takes the electron
from sodium rather than sharing it.
Q5: Water has a relatively high boiling point compared to other molecules its size. Which
intermolecular force is primarily responsible?
A. London dispersion forces
B. Dipole-dipole interactions
C. Hydrogen bonding [CORRECT]
D. Ionic bonding
Correct Answer: C
Rationale: This is correct because water molecules can form hydrogen bonds between
the partially positive hydrogen of one molecule and the partially negative oxygen of
another, and it takes a lot of energy to break those attractions.
Q6: Consider the following molecules: CH4, NH3, and H2O. Which statement correctly
ranks their intermolecular forces from weakest to strongest?
A. CH4 < NH3 < H2O [CORRECT]
B. H2O < NH3 < CH4
C. NH3 < CH4 < H2O
D. CH4 < H2O < NH3
Correct Answer: A
, Rationale: The best answer is A because methane only has weak London dispersion
forces, ammonia can hydrogen bond but with only one lone pair donor, and water forms
an extensive hydrogen-bonding network with two lone pairs and two hydrogens.
Q7: Which molecule is polar?
A. CO2
B. CH4
C. NH3 [CORRECT]
D. CCl4
Correct Answer: C
Rationale: This aligns with molecular geometry—ammonia has a trigonal pyramidal
shape with a lone pair that creates an uneven charge distribution, while the other
molecules have symmetrical shapes that cancel out their bond dipoles.
Q8: Which compound would you expect to be most soluble in water?
A. Hexane (C6H14)
B. Ethanol (C2H5OH) [CORRECT]
C. Benzene (C6H6)
D. Octane (C8H18)
Correct Answer: B
Rationale: The best answer is B because ethanol has that hydroxyl group that can
hydrogen bond with water, while the hydrocarbons are nonpolar and simply don't mix
with polar solvents.
Q9: How many grams of NaCl are needed to prepare 500 mL of a 0.9% (w/v) saline
solution?
A. 0.45 g
B. 4.5 g [CORRECT]
C. 9.0 g
D. 45 g
Correct Answer: B
Rationale: This is correct because percent weight per volume means grams per 100 mL,
so 0.9 g/100 mL × 500 mL gives you 4.5 grams total.
University Actual Exam – Complete Questions and
Answers with Detailed Rationales – Pass
Guaranteed – A+ Graded
Foundations: Atomic Structure, Bonding & Solutions
Q1: A neutral atom of sulfur has 16 protons. How many electrons does it possess?
A. 8
B. 16 [CORRECT]
C. 32
D. 6
Correct Answer: B
Rationale: The best answer is B because in a neutral atom, the number of electrons
always equals the number of protons, so sulfur carries 16 electrons to balance those 16
positive charges in the nucleus.
Q2: Which element has the highest electronegativity?
A. Sodium
B. Oxygen [CORRECT]
C. Calcium
D. Aluminum
Correct Answer: B
Rationale: This aligns with periodic trends—electronegativity increases as you move up
and to the right on the periodic table, so oxygen pulls electron density toward itself more
strongly than the metals listed here.
Q3: How many valence electrons does a neutral oxygen atom have?
A. 2
,B. 4
C. 6 [CORRECT]
D. 8
Correct Answer: C
Rationale: This is basic atomic structure—oxygen sits in group 16 on the periodic table,
so a neutral atom has six electrons in its outermost shell.
Q4: A bond forms between sodium (electronegativity 0.9) and chlorine (electronegativity
3.0). What type of bond is this?
A. Nonpolar covalent
B. Polar covalent
C. Ionic [CORRECT]
D. Hydrogen
Correct Answer: C
Rationale: The best answer is C because that electronegativity difference of 2.1 is well
above the 1.7 cutoff we use in class, meaning chlorine essentially takes the electron
from sodium rather than sharing it.
Q5: Water has a relatively high boiling point compared to other molecules its size. Which
intermolecular force is primarily responsible?
A. London dispersion forces
B. Dipole-dipole interactions
C. Hydrogen bonding [CORRECT]
D. Ionic bonding
Correct Answer: C
Rationale: This is correct because water molecules can form hydrogen bonds between
the partially positive hydrogen of one molecule and the partially negative oxygen of
another, and it takes a lot of energy to break those attractions.
Q6: Consider the following molecules: CH4, NH3, and H2O. Which statement correctly
ranks their intermolecular forces from weakest to strongest?
A. CH4 < NH3 < H2O [CORRECT]
B. H2O < NH3 < CH4
C. NH3 < CH4 < H2O
D. CH4 < H2O < NH3
Correct Answer: A
, Rationale: The best answer is A because methane only has weak London dispersion
forces, ammonia can hydrogen bond but with only one lone pair donor, and water forms
an extensive hydrogen-bonding network with two lone pairs and two hydrogens.
Q7: Which molecule is polar?
A. CO2
B. CH4
C. NH3 [CORRECT]
D. CCl4
Correct Answer: C
Rationale: This aligns with molecular geometry—ammonia has a trigonal pyramidal
shape with a lone pair that creates an uneven charge distribution, while the other
molecules have symmetrical shapes that cancel out their bond dipoles.
Q8: Which compound would you expect to be most soluble in water?
A. Hexane (C6H14)
B. Ethanol (C2H5OH) [CORRECT]
C. Benzene (C6H6)
D. Octane (C8H18)
Correct Answer: B
Rationale: The best answer is B because ethanol has that hydroxyl group that can
hydrogen bond with water, while the hydrocarbons are nonpolar and simply don't mix
with polar solvents.
Q9: How many grams of NaCl are needed to prepare 500 mL of a 0.9% (w/v) saline
solution?
A. 0.45 g
B. 4.5 g [CORRECT]
C. 9.0 g
D. 45 g
Correct Answer: B
Rationale: This is correct because percent weight per volume means grams per 100 mL,
so 0.9 g/100 mL × 500 mL gives you 4.5 grams total.
