C915 CHEM 4405
Chemistry Content Knowledge
FA REVIEW
©WGU 2024/2025
,1. Multiple Choice: Which of the following is a Lewis acid?
A) \( NH_3 \)
B) \( H_2O \)
C) \( BF_3 \)
D) \( NaH \)
Correct Answer: C) \( BF_3 \)
Rationale: A Lewis acid is a compound that can accept a pair of
electrons to form a covalent bond. \( BF_3 \) has an empty p-
orbital and can accept an electron pair.
2. Fill-in-the-Blank: The ________ rule states that atoms are most
stable when they contain eight electrons in their valence shell.
Correct Answer: Octet
Rationale: The octet rule is a chemical rule of thumb that reflects
the observation that elements tend to bond in such a way that each
atom has eight electrons in its valence shell.
3. True/False: The entropy of a system always decreases over time.
Correct Answer: False
Rationale: The second law of thermodynamics states that the
total entropy of an isolated system can never decrease over time.
©WGU 2024/2025
, 4. Multiple Response: Select all that apply. Which of the following
are characteristics of a chemical change?
A) Change in color
B) Formation of a precipitate
C) Change in temperature
D) Change in phase
Correct Answers: A), B), C)
Rationale: Chemical changes are accompanied by the formation
of new substances and involve changes in color, temperature, and
the formation of precipitates, unlike phase changes which are
physical changes.
5. Multiple Choice: What is the name of the principle that states no
two electrons in the same atom can have identical quantum
numbers?
A) Aufbau Principle
B) Hund's Rule
C) Pauli Exclusion Principle
D) Avogadro's Law
Correct Answer: C) Pauli Exclusion Principle
©WGU 2024/2025
Chemistry Content Knowledge
FA REVIEW
©WGU 2024/2025
,1. Multiple Choice: Which of the following is a Lewis acid?
A) \( NH_3 \)
B) \( H_2O \)
C) \( BF_3 \)
D) \( NaH \)
Correct Answer: C) \( BF_3 \)
Rationale: A Lewis acid is a compound that can accept a pair of
electrons to form a covalent bond. \( BF_3 \) has an empty p-
orbital and can accept an electron pair.
2. Fill-in-the-Blank: The ________ rule states that atoms are most
stable when they contain eight electrons in their valence shell.
Correct Answer: Octet
Rationale: The octet rule is a chemical rule of thumb that reflects
the observation that elements tend to bond in such a way that each
atom has eight electrons in its valence shell.
3. True/False: The entropy of a system always decreases over time.
Correct Answer: False
Rationale: The second law of thermodynamics states that the
total entropy of an isolated system can never decrease over time.
©WGU 2024/2025
, 4. Multiple Response: Select all that apply. Which of the following
are characteristics of a chemical change?
A) Change in color
B) Formation of a precipitate
C) Change in temperature
D) Change in phase
Correct Answers: A), B), C)
Rationale: Chemical changes are accompanied by the formation
of new substances and involve changes in color, temperature, and
the formation of precipitates, unlike phase changes which are
physical changes.
5. Multiple Choice: What is the name of the principle that states no
two electrons in the same atom can have identical quantum
numbers?
A) Aufbau Principle
B) Hund's Rule
C) Pauli Exclusion Principle
D) Avogadro's Law
Correct Answer: C) Pauli Exclusion Principle
©WGU 2024/2025
