CHEM 103 GENERAL CHEMISTRY I COMPLETE EXAM
PACK MODULES 1 TO 6 AND FINAL EXAM QUESTIONS &
ANSWERS PORTAGE LEARNING
This comprehensive CHEM 103 exam bank features meticulously
crafted multiple-choice questions complete with answers and detailed
rationales covering Modules 1 through 6 and the cumulative final exam.
It provides exhaustive coverage of core chemistry principles including
stoichiometry, molecular geometry, gas laws, thermochemistry, and
chemical equilibrium equations. The diagnostic question profiles and
step-by-step mathematical breakdowns serve as an ideal high-yield
study companion optimized for student mastery and exam preparation.
1. What is the correct number of significant figures in
the measurement 0.0450 grams?
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
*Rationale: Leading zeros are never significant.
Trailing zeros after a decimal point are significant.
Therefore, only the digits 4, 5, and the final 0 are
significant. *
2. Which of the following represents a chemical
change?
, A) Boiling water
B) Dissolving salt in water
C) Rusting of an iron nail
D) Crushing a sugar cube
Answer: C) Rusting of an iron nail
*Rationale: Rusting forms a new chemical
substance (iron oxide), which alters the chemical
composition. The other choices represent physical
changes of state or mixture formation. *
3. An atom contains 15 protons, 16 neutrons, and 15
electrons. What is the identity of this element?
A) Sulfur
B) Oxygen
C) Phosphorus
D) Gallium
Answer: C) Phosphorus
*Rationale: The identity of an element is
determined solely by its atomic number, which
equals the number of protons. Phosphorus has an
atomic number of 15. *
,4. What is the density of a metal block that has a mass
of 45.0 g and a volume of 5.0 cm³?
A) 0.11 g/cm³
B) 9.0 g/cm³
C) 40.0 g/cm³
D) 225 g/cm³
Answer: B) 9.0 g/cm³
*Rationale: Density is calculated using the formula
\(D = \frac{m}{V}\). Plugging in the values gives
\(\frac{45.0\text{ g}}{5.0\text{ cm}^3} = 9.0\text{
g/cm}^3\). *
5. Which subatomic particle carries a negative charge
and has a negligible mass?
A) Proton
B) Neutron
C) Electron
D) Alpha particle
Answer: C) Electron
*Rationale: Electrons possess a relative charge of -1
and a mass of approximately \(\frac{1}{1836}\) of a
, proton, making their mass negligible in atomic mass
calculations. *
6. What is the empirical formula of a compound that is
40.0% Carbon, 6.7% Hydrogen, and 53.3% Oxygen by
mass?
A) CH2O
B) CHO
C) C2H4O2
D) CHO2
Answer: A) CH2O
*Rationale: Assuming a 100g sample gives 3.33 mol
C, 6.63 mol H, and 3.33 mol O. Dividing each by the
smallest value (3.33) yields a 1:2:1 molar ratio,
simplifying to CH₂O. *
7. How many moles of Al₂O₃ are present in an 85.0-
gram sample of the compound? (Molar mass of
Al₂O₃ = 101.96 g/mol)
A) 0.834 moles
B) 1.20 moles
C) 8.67 moles
PACK MODULES 1 TO 6 AND FINAL EXAM QUESTIONS &
ANSWERS PORTAGE LEARNING
This comprehensive CHEM 103 exam bank features meticulously
crafted multiple-choice questions complete with answers and detailed
rationales covering Modules 1 through 6 and the cumulative final exam.
It provides exhaustive coverage of core chemistry principles including
stoichiometry, molecular geometry, gas laws, thermochemistry, and
chemical equilibrium equations. The diagnostic question profiles and
step-by-step mathematical breakdowns serve as an ideal high-yield
study companion optimized for student mastery and exam preparation.
1. What is the correct number of significant figures in
the measurement 0.0450 grams?
A) 2
B) 3
C) 4
D) 5
Answer: B) 3
*Rationale: Leading zeros are never significant.
Trailing zeros after a decimal point are significant.
Therefore, only the digits 4, 5, and the final 0 are
significant. *
2. Which of the following represents a chemical
change?
, A) Boiling water
B) Dissolving salt in water
C) Rusting of an iron nail
D) Crushing a sugar cube
Answer: C) Rusting of an iron nail
*Rationale: Rusting forms a new chemical
substance (iron oxide), which alters the chemical
composition. The other choices represent physical
changes of state or mixture formation. *
3. An atom contains 15 protons, 16 neutrons, and 15
electrons. What is the identity of this element?
A) Sulfur
B) Oxygen
C) Phosphorus
D) Gallium
Answer: C) Phosphorus
*Rationale: The identity of an element is
determined solely by its atomic number, which
equals the number of protons. Phosphorus has an
atomic number of 15. *
,4. What is the density of a metal block that has a mass
of 45.0 g and a volume of 5.0 cm³?
A) 0.11 g/cm³
B) 9.0 g/cm³
C) 40.0 g/cm³
D) 225 g/cm³
Answer: B) 9.0 g/cm³
*Rationale: Density is calculated using the formula
\(D = \frac{m}{V}\). Plugging in the values gives
\(\frac{45.0\text{ g}}{5.0\text{ cm}^3} = 9.0\text{
g/cm}^3\). *
5. Which subatomic particle carries a negative charge
and has a negligible mass?
A) Proton
B) Neutron
C) Electron
D) Alpha particle
Answer: C) Electron
*Rationale: Electrons possess a relative charge of -1
and a mass of approximately \(\frac{1}{1836}\) of a
, proton, making their mass negligible in atomic mass
calculations. *
6. What is the empirical formula of a compound that is
40.0% Carbon, 6.7% Hydrogen, and 53.3% Oxygen by
mass?
A) CH2O
B) CHO
C) C2H4O2
D) CHO2
Answer: A) CH2O
*Rationale: Assuming a 100g sample gives 3.33 mol
C, 6.63 mol H, and 3.33 mol O. Dividing each by the
smallest value (3.33) yields a 1:2:1 molar ratio,
simplifying to CH₂O. *
7. How many moles of Al₂O₃ are present in an 85.0-
gram sample of the compound? (Molar mass of
Al₂O₃ = 101.96 g/mol)
A) 0.834 moles
B) 1.20 moles
C) 8.67 moles
