Chem 103 Module 1 to 6 Exam with Verified
Answers (100 out of 100) Portage Learning
(2025/2026 Update)
Module 1: Foundations & Stoichiometry
1. The law that states "A compound always contains the same elements in the
same proportions by mass" is:
A. Law of Multiple Proportions
B. Law of Conservation of Mass
C. Law of Definite Proportions
D. Law of Modern Atomic Theory
2. How many significant figures are in the number 0.0050670?
A. 4
B. 5
C. 6
D. 7
3. The result of the calculation (3.25 x 10⁻⁷) / (5.0 x 10²) is:
A. 6.5 x 10⁻¹⁰
B. 6.5 x 10⁻⁴
C. 6.5 x 10⁴
D. 6.5 x 10⁵
4. A sample of a compound is decomposed and found to contain 1.27 g of S
and 1.42 g of O. What is its empirical formula?
A. SO
B. SO₂
C. S₂O
D. SO₃
5. What is the mass percent of carbon in glucose, C₆H₁₂O₆?
A. 6.7%
B. 40.0%
,C. 72.0%
D. 12.0%
6. In the reaction 2H₂ + O₂ → 2H₂O, if you start with 4.0 moles of H₂ and 3.0
moles of O₂, what is the limiting reactant?
A. H₂
B. O₂
C. H₂O
D. There is no limiting reactant.
7. The theoretical yield of a reaction is 55.2 g, but the actual yield is 48.9 g.
What is the percent yield?
A. 113%
B. 88.6%
C. 11.4%
D. 6.3%
8. Which of the following is a pure substance?
A. Saltwater
B. Air
C. Graphite
D. Milk
9. A student weighs a sample as 2.500 g. The true value is 2.501 g. What is the
percent error?
A. 0.04%
B. 0.4%
C. 4.0%
D. 40.0%
10. What is the molar mass of calcium nitrate, Ca(NO₃)₂?
A. 164.10 g/mol
B. 102.09 g/mol
C. 132.10 g/mol
D. 150.09 g/mol
, Module 2: Atomic Structure & Periodicity
11. Which subatomic particle has the smallest mass?
A. Proton
B. Neutron
C. Electron
D. Nucleus
12. The atomic number of an element is defined by the number of:
A. Protons
B. Neutrons
C. Electrons
D. Protons and Neutrons
13. Isotopes of an element have the same number of ______ but different
numbers of ______.
A. electrons, protons
B. protons, neutrons
C. neutrons, electrons
D. protons, electrons
14. What is the correct electron configuration for a neutral atom of Iron (Fe,
Z=26)?
A. [Ar] 4s² 3d⁶
B. [Ar] 4s² 4d⁶
C. [Ar] 4s² 3d⁵
D. [Ar] 4s² 3d⁶
15. Which of the following quantum numbers describes the shape of an
orbital?
A. n (principal)
B. l (azimuthal)
C. m_l (magnetic)
D. m_s (spin)
16. How many orbitals are in the n=3 energy level?
A. 3
Answers (100 out of 100) Portage Learning
(2025/2026 Update)
Module 1: Foundations & Stoichiometry
1. The law that states "A compound always contains the same elements in the
same proportions by mass" is:
A. Law of Multiple Proportions
B. Law of Conservation of Mass
C. Law of Definite Proportions
D. Law of Modern Atomic Theory
2. How many significant figures are in the number 0.0050670?
A. 4
B. 5
C. 6
D. 7
3. The result of the calculation (3.25 x 10⁻⁷) / (5.0 x 10²) is:
A. 6.5 x 10⁻¹⁰
B. 6.5 x 10⁻⁴
C. 6.5 x 10⁴
D. 6.5 x 10⁵
4. A sample of a compound is decomposed and found to contain 1.27 g of S
and 1.42 g of O. What is its empirical formula?
A. SO
B. SO₂
C. S₂O
D. SO₃
5. What is the mass percent of carbon in glucose, C₆H₁₂O₆?
A. 6.7%
B. 40.0%
,C. 72.0%
D. 12.0%
6. In the reaction 2H₂ + O₂ → 2H₂O, if you start with 4.0 moles of H₂ and 3.0
moles of O₂, what is the limiting reactant?
A. H₂
B. O₂
C. H₂O
D. There is no limiting reactant.
7. The theoretical yield of a reaction is 55.2 g, but the actual yield is 48.9 g.
What is the percent yield?
A. 113%
B. 88.6%
C. 11.4%
D. 6.3%
8. Which of the following is a pure substance?
A. Saltwater
B. Air
C. Graphite
D. Milk
9. A student weighs a sample as 2.500 g. The true value is 2.501 g. What is the
percent error?
A. 0.04%
B. 0.4%
C. 4.0%
D. 40.0%
10. What is the molar mass of calcium nitrate, Ca(NO₃)₂?
A. 164.10 g/mol
B. 102.09 g/mol
C. 132.10 g/mol
D. 150.09 g/mol
, Module 2: Atomic Structure & Periodicity
11. Which subatomic particle has the smallest mass?
A. Proton
B. Neutron
C. Electron
D. Nucleus
12. The atomic number of an element is defined by the number of:
A. Protons
B. Neutrons
C. Electrons
D. Protons and Neutrons
13. Isotopes of an element have the same number of ______ but different
numbers of ______.
A. electrons, protons
B. protons, neutrons
C. neutrons, electrons
D. protons, electrons
14. What is the correct electron configuration for a neutral atom of Iron (Fe,
Z=26)?
A. [Ar] 4s² 3d⁶
B. [Ar] 4s² 4d⁶
C. [Ar] 4s² 3d⁵
D. [Ar] 4s² 3d⁶
15. Which of the following quantum numbers describes the shape of an
orbital?
A. n (principal)
B. l (azimuthal)
C. m_l (magnetic)
D. m_s (spin)
16. How many orbitals are in the n=3 energy level?
A. 3
